@end itemize
-@section drawbox
+@c man end AUDIO SOURCES
-Draw a colored box on the input image.
+@chapter Audio Sinks
+@c man begin AUDIO SINKS
-It accepts the syntax:
-@example
-drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
-@end example
+Below is a description of the currently available audio sinks.
-@table @option
+@section abuffersink
-@item x, y
-Specify the top left corner coordinates of the box. Default to 0.
+Buffer audio frames, and make them available to the end of filter chain.
-@item width, height
-Specify the width and height of the box, if 0 they are interpreted as
-the input width and height. Default to 0.
+This sink is mainly intended for programmatic use, in particular
+through the interface defined in @file{libavfilter/buffersink.h}.
-@item color
-Specify the color of the box to write, it can be the name of a color
-(case insensitive match) or a 0xRRGGBB[AA] sequence.
-@end table
+It requires a pointer to an AVABufferSinkContext structure, which
+defines the incoming buffers' formats, to be passed as the opaque
+parameter to @code{avfilter_init_filter} for initialization.
-Follow some examples:
-@example
-# draw a black box around the edge of the input image
-drawbox
+@section anullsink
-# draw a box with color red and an opacity of 50%
-drawbox=10:20:200:60:red@@0.5"
-@end example
+Null audio sink, do absolutely nothing with the input audio. It is
+mainly useful as a template and to be employed in analysis / debugging
+tools.
-@section drawtext
+@section abuffersink
+This sink is intended for programmatic use. Frames that arrive on this sink can
+be retrieved by the calling program using the interface defined in
+@file{libavfilter/buffersink.h}.
-Draw text string or text from specified file on top of video using the
-libfreetype library.
+This filter accepts no parameters.
-To enable compilation of this filter you need to configure Libav with
-@code{--enable-libfreetype}.
+@c man end AUDIO SINKS
-The filter also recognizes strftime() sequences in the provided text
-and expands them accordingly. Check the documentation of strftime().
+@chapter Video Filters
+@c man begin VIDEO FILTERS
-The filter accepts parameters as a list of @var{key}=@var{value} pairs,
-separated by ":".
+When you configure your FFmpeg build, you can disable any of the
+existing filters using @code{--disable-filters}.
+The configure output will show the video filters included in your
+build.
-The description of the accepted parameters follows.
+Below is a description of the currently available video filters.
-@table @option
+@section alphaextract
-@item fontfile
-The font file to be used for drawing text. Path must be included.
-This parameter is mandatory.
+Extract the alpha component from the input as a grayscale video. This
+is especially useful with the @var{alphamerge} filter.
-@item text
-The text string to be drawn. The text must be a sequence of UTF-8
-encoded characters.
-This parameter is mandatory if no file is specified with the parameter
-@var{textfile}.
+@section alphamerge
-@item textfile
-A text file containing text to be drawn. The text must be a sequence
-of UTF-8 encoded characters.
+Add or replace the alpha component of the primary input with the
+grayscale value of a second input. This is intended for use with
+@var{alphaextract} to allow the transmission or storage of frame
+sequences that have alpha in a format that doesn't support an alpha
+channel.
-This parameter is mandatory if no text string is specified with the
-parameter @var{text}.
+For example, to reconstruct full frames from a normal YUV-encoded video
+and a separate video created with @var{alphaextract}, you might use:
+@example
+movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
+@end example
-If both text and textfile are specified, an error is thrown.
+Since this filter is designed for reconstruction, it operates on frame
+sequences without considering timestamps, and terminates when either
+input reaches end of stream. This will cause problems if your encoding
+pipeline drops frames. If you're trying to apply an image as an
+overlay to a video stream, consider the @var{overlay} filter instead.
-@item x, y
-The offsets where text will be drawn within the video frame.
-Relative to the top/left border of the output image.
-They accept expressions similar to the @ref{overlay} filter:
-@table @option
+@section ass
-@item x, y
-the computed values for @var{x} and @var{y}. They are evaluated for
-each new frame.
+Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
+and libavformat to work. On the other hand, it is limited to ASS (Advanced
+Substation Alpha) subtitles files.
-@item main_w, main_h
-main input width and height
+@section bbox
-@item W, H
-same as @var{main_w} and @var{main_h}
+Compute the bounding box for the non-black pixels in the input frame
+luminance plane.
-@item text_w, text_h
-rendered text width and height
+This filter computes the bounding box containing all the pixels with a
+luminance value greater than the minimum allowed value.
+The parameters describing the bounding box are printed on the filter
+log.
-@item w, h
-same as @var{text_w} and @var{text_h}
+@section blackdetect
-@item n
-the number of frames processed, starting from 0
+Detect video intervals that are (almost) completely black. Can be
+useful to detect chapter transitions, commercials, or invalid
+recordings. Output lines contains the time for the start, end and
+duration of the detected black interval expressed in seconds.
-@item t
-timestamp expressed in seconds, NAN if the input timestamp is unknown
+In order to display the output lines, you need to set the loglevel at
+least to the AV_LOG_INFO value.
-@end table
+This filter accepts a list of options in the form of
+@var{key}=@var{value} pairs separated by ":". A description of the
+accepted options follows.
-The default value of @var{x} and @var{y} is 0.
+@table @option
+@item black_min_duration, d
+Set the minimum detected black duration expressed in seconds. It must
+be a non-negative floating point number.
-@item fontsize
-The font size to be used for drawing text.
-The default value of @var{fontsize} is 16.
+Default value is 2.0.
-@item fontcolor
-The color to be used for drawing fonts.
-Either a string (e.g. "red") or in 0xRRGGBB[AA] format
-(e.g. "0xff000033"), possibly followed by an alpha specifier.
-The default value of @var{fontcolor} is "black".
+@item picture_black_ratio_th, pic_th
+Set the threshold for considering a picture "black".
+Express the minimum value for the ratio:
+@example
+@var{nb_black_pixels} / @var{nb_pixels}
+@end example
-@item boxcolor
-The color to be used for drawing box around text.
-Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
-(e.g. "0xff00ff"), possibly followed by an alpha specifier.
-The default value of @var{boxcolor} is "white".
+for which a picture is considered black.
+Default value is 0.98.
-@item box
-Used to draw a box around text using background color.
-Value should be either 1 (enable) or 0 (disable).
-The default value of @var{box} is 0.
+@item pixel_black_th, pix_th
+Set the threshold for considering a pixel "black".
-@item shadowx, shadowy
-The x and y offsets for the text shadow position with respect to the
-position of the text. They can be either positive or negative
-values. Default value for both is "0".
+The threshold expresses the maximum pixel luminance value for which a
+pixel is considered "black". The provided value is scaled according to
+the following equation:
+@example
+@var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
+@end example
-@item shadowcolor
-The color to be used for drawing a shadow behind the drawn text. It
-can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
+@var{luminance_range_size} and @var{luminance_minimum_value} depend on
+the input video format, the range is [0-255] for YUV full-range
+formats and [16-235] for YUV non full-range formats.
+
+Default value is 0.10.
+@end table
+
+The following example sets the maximum pixel threshold to the minimum
+value, and detects only black intervals of 2 or more seconds:
+@example
+blackdetect=d=2:pix_th=0.00
+@end example
+
+@section blackframe
+
+Detect frames that are (almost) completely black. Can be useful to
+detect chapter transitions or commercials. Output lines consist of
+the frame number of the detected frame, the percentage of blackness,
+the position in the file if known or -1 and the timestamp in seconds.
+
+In order to display the output lines, you need to set the loglevel at
+least to the AV_LOG_INFO value.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+blackframe[=@var{amount}[:@var{threshold}]].
+
- A description of the accepted options follows.
++The filter accepts the following options:
+
+@table @option
++
+@item amount
- Set the percentage of pixels that have to be below the
- threshold to enable black detection. Default value is 98.
++The percentage of the pixels that have to be below the threshold, defaults to
++98.
+
+@item threshold
- Set the threshold below which a pixel value is considered
- black. Default value is 32.
++Threshold below which a pixel value is considered black, defaults to 32.
++
+@end table
+
+@section blend
+
+Blend two video frames into each other.
+
+It takes two input streams and outputs one stream, the first input is the
+"top" layer and second input is "bottom" layer.
+Output terminates when shortest input terminates.
+
+This filter accepts a list of options in the form of @var{key}=@var{value}
+pairs separated by ":". A description of the accepted options follows.
+
+@table @option
+@item c0_mode
+@item c1_mode
+@item c2_mode
+@item c3_mode
+@item all_mode
+Set blend mode for specific pixel component or all pixel components in case
+of @var{all_mode}. Default value is @code{normal}.
+
+Available values for component modes are:
+@table @samp
+@item addition
+@item and
+@item average
+@item burn
+@item darken
+@item difference
+@item divide
+@item dodge
+@item exclusion
+@item hardlight
+@item lighten
+@item multiply
+@item negation
+@item normal
+@item or
+@item overlay
+@item phoenix
+@item pinlight
+@item reflect
+@item screen
+@item softlight
+@item subtract
+@item vividlight
+@item xor
+@end table
+
+@item c0_opacity
+@item c1_opacity
+@item c2_opacity
+@item c3_opacity
+@item all_opacity
+Set blend opacity for specific pixel component or all pixel components in case
+of @var{all_opacity}. Only used in combination with pixel component blend modes.
+
+@item c0_expr
+@item c1_expr
+@item c2_expr
+@item c3_expr
+@item all_expr
+Set blend expression for specific pixel component or all pixel components in case
+of @var{all_expr}. Note that related mode options will be ignored if those are set.
+
+The expressions can use the following variables:
+
+@table @option
+@item N
+The sequential number of the filtered frame, starting from @code{0}.
+
+@item X
+@item Y
+the coordinates of the current sample
+
+@item W
+@item H
+the width and height of currently filtered plane
+
+@item SW
+@item SH
+Width and height scale depending on the currently filtered plane. It is the
+ratio between the corresponding luma plane number of pixels and the current
+plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
+@code{0.5,0.5} for chroma planes.
+
+@item T
+Time of the current frame, expressed in seconds.
+
+@item TOP, A
+Value of pixel component at current location for first video frame (top layer).
+
+@item BOTTOM, B
+Value of pixel component at current location for second video frame (bottom layer).
+@end table
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Apply transition from bottom layer to top layer in first 10 seconds:
+@example
+blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
+@end example
+
+@item
+Apply 1x1 checkerboard effect:
+@example
+blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
+@end example
+@end itemize
+
+@section boxblur
+
+Apply boxblur algorithm to the input video.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+@option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
+
+A description of the accepted options follows.
+
+@table @option
+@item luma_radius, lr
+@item chroma_radius, cr
+@item alpha_radius, ar
+Set an expression for the box radius in pixels used for blurring the
+corresponding input plane.
+
+The radius value must be a non-negative number, and must not be
+greater than the value of the expression @code{min(w,h)/2} for the
+luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
+planes.
+
+Default value for @option{luma_radius} is "2". If not specified,
+@option{chroma_radius} and @option{alpha_radius} default to the
+corresponding value set for @option{luma_radius}.
+
+The expressions can contain the following constants:
+@table @option
+@item w, h
+the input width and height in pixels
+
+@item cw, ch
+the input chroma image width and height in pixels
+
+@item hsub, vsub
+horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+@end table
+
+@item luma_power, lp
+@item chroma_power, cp
+@item alpha_power, ap
+Specify how many times the boxblur filter is applied to the
+corresponding plane.
+
+Default value for @option{luma_power} is 2. If not specified,
+@option{chroma_power} and @option{alpha_power} default to the
+corresponding value set for @option{luma_power}.
+
+A value of 0 will disable the effect.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Apply a boxblur filter with luma, chroma, and alpha radius
+set to 2:
+@example
+boxblur=2:1
+@end example
+
+@item
+Set luma radius to 2, alpha and chroma radius to 0:
+@example
+boxblur=2:1:cr=0:ar=0
+@end example
+
+@item
+Set luma and chroma radius to a fraction of the video dimension:
+@example
+boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
+@end example
+@end itemize
+
+@section colormatrix
+
+Convert color matrix.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+@var{src}:@var{dst}.
+
+A description of the accepted options follows:
+@table @option
+@item src
+@item dst
+Specify the source and destination color matrix. Both values must be
+specified.
+
+The accepted values are:
+@table @samp
+@item bt709
+BT.709
+
+@item bt601
+BT.601
+
+@item smpte240m
+SMPTE-240M
+
+@item fcc
+FCC
+@end table
+@end table
+
+For example to convert from BT.601 to SMPTE-240M, use the command:
+@example
+colormatrix=bt601:smpte240m
+@end example
+
+@section copy
+
+Copy the input source unchanged to the output. Mainly useful for
+testing purposes.
+
+@section crop
+
+Crop the input video.
+
+This filter accepts a list of @var{key}=@var{value} pairs as argument,
+separated by ':'. If the key of the first options is omitted, the
+arguments are interpreted according to the syntax
+@var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
+
+A description of the accepted options follows:
+@table @option
+@item w, out_w
+Set the crop area width. It defaults to @code{iw}.
+This expression is evaluated only once during the filter
+configuration.
+
+@item h, out_h
+Set the crop area height. It defaults to @code{ih}.
+This expression is evaluated only once during the filter
+configuration.
+
+@item x
+Set the expression for the x top-left coordinate of the cropped area.
+It defaults to @code{(in_w-out_w)/2}.
+This expression is evaluated per-frame.
+
+@item y
+Set the expression for the y top-left coordinate of the cropped area.
+It defaults to @code{(in_h-out_h)/2}.
+This expression is evaluated per-frame.
+
+@item keep_aspect
+If set to 1 will force the output display aspect ratio
+to be the same of the input, by changing the output sample aspect
+ratio. It defaults to 0.
+@end table
+
+The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
+expressions containing the following constants:
+
+@table @option
+@item x, y
+the computed values for @var{x} and @var{y}. They are evaluated for
+each new frame.
+
+@item in_w, in_h
+the input width and height
+
+@item iw, ih
+same as @var{in_w} and @var{in_h}
+
+@item out_w, out_h
+the output (cropped) width and height
+
+@item ow, oh
+same as @var{out_w} and @var{out_h}
+
+@item a
+same as @var{iw} / @var{ih}
+
+@item sar
+input sample aspect ratio
+
+@item dar
+input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
+
+@item hsub, vsub
+horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+
+@item n
+the number of input frame, starting from 0
+
+@item t
+timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+@end table
+
+The expression for @var{out_w} may depend on the value of @var{out_h},
+and the expression for @var{out_h} may depend on @var{out_w}, but they
+cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
+evaluated after @var{out_w} and @var{out_h}.
+
+The @var{x} and @var{y} parameters specify the expressions for the
+position of the top-left corner of the output (non-cropped) area. They
+are evaluated for each frame. If the evaluated value is not valid, it
+is approximated to the nearest valid value.
+
+The expression for @var{x} may depend on @var{y}, and the expression
+for @var{y} may depend on @var{x}.
+
+@subsection Examples
+
+@itemize
+@item
+Crop area with size 100x100 at position (12,34).
+@example
+crop=100:100:12:34
+@end example
+
+Using named options, the example above becomes:
+@example
+crop=w=100:h=100:x=12:y=34
+@end example
+
+@item
+Crop the central input area with size 100x100:
+@example
+crop=100:100
+@end example
+
+@item
+Crop the central input area with size 2/3 of the input video:
+@example
+crop=2/3*in_w:2/3*in_h
+@end example
+
+@item
+Crop the input video central square:
+@example
+crop=in_h
+@end example
+
+@item
+Delimit the rectangle with the top-left corner placed at position
+100:100 and the right-bottom corner corresponding to the right-bottom
+corner of the input image:
+@example
+crop=in_w-100:in_h-100:100:100
+@end example
+
+@item
+Crop 10 pixels from the left and right borders, and 20 pixels from
+the top and bottom borders
+@example
+crop=in_w-2*10:in_h-2*20
+@end example
+
+@item
+Keep only the bottom right quarter of the input image:
+@example
+crop=in_w/2:in_h/2:in_w/2:in_h/2
+@end example
+
+@item
+Crop height for getting Greek harmony:
+@example
+crop=in_w:1/PHI*in_w
+@end example
+
+@item
+Appply trembling effect:
+@example
+crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)
+@end example
+
+@item
+Apply erratic camera effect depending on timestamp:
+@example
+crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
+@end example
+
+@item
+Set x depending on the value of y:
+@example
+crop=in_w/2:in_h/2:y:10+10*sin(n/10)
+@end example
+@end itemize
+
+@section cropdetect
+
+Auto-detect crop size.
+
+Calculate necessary cropping parameters and prints the recommended
+parameters through the logging system. The detected dimensions
+correspond to the non-black area of the input video.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+[@option{limit}[:@option{round}[:@option{reset}]]].
+
+A description of the accepted options follows.
+
+@table @option
+
+@item limit
+Set higher black value threshold, which can be optionally specified
+from nothing (0) to everything (255). An intensity value greater
+to the set value is considered non-black. Default value is 24.
+
+@item round
+Set the value for which the width/height should be divisible by. The
+offset is automatically adjusted to center the video. Use 2 to get
+only even dimensions (needed for 4:2:2 video). 16 is best when
+encoding to most video codecs. Default value is 16.
+
+@item reset
+Set the counter that determines after how many frames cropdetect will
+reset the previously detected largest video area and start over to
+detect the current optimal crop area. Default value is 0.
+
+This can be useful when channel logos distort the video area. 0
+indicates never reset and return the largest area encountered during
+playback.
+@end table
+
+@section curves
+
+Apply color adjustments using curves.
+
+This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
+component (red, green and blue) has its values defined by @var{N} key points
+tied from each other using a smooth curve. The x-axis represents the pixel
+values from the input frame, and the y-axis the new pixel values to be set for
+the output frame.
+
+By default, a component curve is defined by the two points @var{(0;0)} and
+@var{(1;1)}. This creates a straight line where each original pixel value is
+"adjusted" to its own value, which means no change to the image.
+
+The filter allows you to redefine these two points and add some more. A new
+curve (using a natural cubic spline interpolation) will be define to pass
+smoothly through all these new coordinates. The new defined points needs to be
+strictly increasing over the x-axis, and their @var{x} and @var{y} values must
+be in the @var{[0;1]} interval. If the computed curves happened to go outside
+the vector spaces, the values will be clipped accordingly.
+
+If there is no key point defined in @code{x=0}, the filter will automatically
+insert a @var{(0;0)} point. In the same way, if there is no key point defined
+in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+curves[=@var{preset}].
+
+A description of the accepted parameters follows.
+
+@table @option
+@item red, r
+Set the key points for the red component.
+@item green, g
+Set the key points for the green component.
+@item blue, b
+Set the key points for the blue component.
+@item preset
+Select one of the available color presets. This option can not be used in
+addition to the @option{r}, @option{g}, @option{b} parameters.
+Available presets are:
+@table @samp
+@item color_negative
+@item cross_process
+@item darker
+@item increase_contrast
+@item lighter
+@item linear_contrast
+@item medium_contrast
+@item negative
+@item strong_contrast
+@item vintage
+@end table
+Default is unset.
+@end table
+
+To avoid some filtergraph syntax conflicts, each key points list need to be
+defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
+
+@subsection Examples
+
+@itemize
+@item
+Increase slightly the middle level of blue:
+@example
+curves=blue='0.5/0.58'
+@end example
+
+@item
+Vintage effect:
+@example
+curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
+@end example
+Here we obtain the following coordinates for each components:
+@table @var
+@item red
+@code{(0;0.11) (0.42;0.51) (1;0.95)}
+@item green
+@code{(0;0) (0.50;0.48) (1;1)}
+@item blue
+@code{(0;0.22) (0.49;0.44) (1;0.80)}
+@end table
+
+@item
+The previous example can also be achieved with the associated built-in preset:
+@example
+curves=preset=vintage
+@end example
+
+@item
+Or simply:
+@example
+curves=vintage
+@end example
+@end itemize
+
+@section decimate
+
+Drop frames that do not differ greatly from the previous frame in
+order to reduce frame rate.
+
+The main use of this filter is for very-low-bitrate encoding
+(e.g. streaming over dialup modem), but it could in theory be used for
+fixing movies that were inverse-telecined incorrectly.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax:
+@option{max}:@option{hi}:@option{lo}:@option{frac}.
+
+A description of the accepted options follows.
+
+@table @option
+@item max
+Set the maximum number of consecutive frames which can be dropped (if
+positive), or the minimum interval between dropped frames (if
+negative). If the value is 0, the frame is dropped unregarding the
+number of previous sequentially dropped frames.
+
+Default value is 0.
+
+@item hi
+@item lo
+@item frac
+Set the dropping threshold values.
+
+Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
+represent actual pixel value differences, so a threshold of 64
+corresponds to 1 unit of difference for each pixel, or the same spread
+out differently over the block.
+
+A frame is a candidate for dropping if no 8x8 blocks differ by more
+than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
+meaning the whole image) differ by more than a threshold of @option{lo}.
+
+Default value for @option{hi} is 64*12, default value for @option{lo} is
+64*5, and default value for @option{frac} is 0.33.
+@end table
+
+@section delogo
+
+Suppress a TV station logo by a simple interpolation of the surrounding
+pixels. Just set a rectangle covering the logo and watch it disappear
+(and sometimes something even uglier appear - your mileage may vary).
+
+The filter accepts parameters as a string of the form
+"@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
+@var{key}=@var{value} pairs, separated by ":".
+
+The description of the accepted parameters follows.
+
+@table @option
+
+@item x, y
+Specify the top left corner coordinates of the logo. They must be
+specified.
+
+@item w, h
+Specify the width and height of the logo to clear. They must be
+specified.
+
+@item band, t
+Specify the thickness of the fuzzy edge of the rectangle (added to
+@var{w} and @var{h}). The default value is 4.
+
+@item show
+When set to 1, a green rectangle is drawn on the screen to simplify
+finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
+@var{band} is set to 4. The default value is 0.
+
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Set a rectangle covering the area with top left corner coordinates 0,0
+and size 100x77, setting a band of size 10:
+@example
+delogo=0:0:100:77:10
+@end example
+
+@item
+As the previous example, but use named options:
+@example
+delogo=x=0:y=0:w=100:h=77:band=10
+@end example
+
+@end itemize
+
+@section deshake
+
+Attempt to fix small changes in horizontal and/or vertical shift. This
+filter helps remove camera shake from hand-holding a camera, bumping a
+tripod, moving on a vehicle, etc.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}:@var{opencl}.
+
+A description of the accepted parameters follows.
+
+@table @option
+
+@item x, y, w, h
+Specify a rectangular area where to limit the search for motion
+vectors.
+If desired the search for motion vectors can be limited to a
+rectangular area of the frame defined by its top left corner, width
+and height. These parameters have the same meaning as the drawbox
+filter which can be used to visualise the position of the bounding
+box.
+
+This is useful when simultaneous movement of subjects within the frame
+might be confused for camera motion by the motion vector search.
+
+If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
+then the full frame is used. This allows later options to be set
+without specifying the bounding box for the motion vector search.
+
+Default - search the whole frame.
+
+@item rx, ry
+Specify the maximum extent of movement in x and y directions in the
+range 0-64 pixels. Default 16.
+
+@item edge
+Specify how to generate pixels to fill blanks at the edge of the
+frame. Available values are:
+@table @samp
+@item blank, 0
+Fill zeroes at blank locations
+@item original, 1
+Original image at blank locations
+@item clamp, 2
+Extruded edge value at blank locations
+@item mirror, 3
+Mirrored edge at blank locations
+@end table
+Default value is @samp{mirror}.
+
+@item blocksize
+Specify the blocksize to use for motion search. Range 4-128 pixels,
+default 8.
+
+@item contrast
+Specify the contrast threshold for blocks. Only blocks with more than
+the specified contrast (difference between darkest and lightest
+pixels) will be considered. Range 1-255, default 125.
+
+@item search
+Specify the search strategy. Available values are:
+@table @samp
+@item exhaustive, 0
+Set exhaustive search
+@item less, 1
+Set less exhaustive search.
+@end table
+Default value is @samp{exhaustive}.
+
+@item filename
+If set then a detailed log of the motion search is written to the
+specified file.
+
+@item opencl
+If set to 1, specify using OpenCL capabilities, only available if
+FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
+
+@end table
+
+@section drawbox
+
+Draw a colored box on the input image.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+@option{x}:@option{y}:@option{width}:@option{height}:@option{color}:@option{thickness}.
+
+A description of the accepted options follows.
+
+@table @option
+@item x, y
+Specify the top left corner coordinates of the box. Default to 0.
+
+@item width, w
+@item height, h
+Specify the width and height of the box, if 0 they are interpreted as
+the input width and height. Default to 0.
+
+@item color, c
+Specify the color of the box to write, it can be the name of a color
+(case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
+value @code{invert} is used, the box edge color is the same as the
+video with inverted luma.
+
+@item thickness, t
+Set the thickness of the box edge. Default value is @code{4}.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Draw a black box around the edge of the input image:
+@example
+drawbox
+@end example
+
+@item
+Draw a box with color red and an opacity of 50%:
+@example
+drawbox=10:20:200:60:red@@0.5
+@end example
+
+The previous example can be specified as:
+@example
+drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
+@end example
+
+@item
+Fill the box with pink color:
+@example
+drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
+@end example
+@end itemize
+
+@anchor{drawtext}
+@section drawtext
+
+Draw text string or text from specified file on top of video using the
+libfreetype library.
+
+To enable compilation of this filter you need to configure FFmpeg with
+@code{--enable-libfreetype}.
+
+@subsection Syntax
+
+The filter accepts parameters as a list of @var{key}=@var{value} pairs,
+separated by ":".
+
+The description of the accepted parameters follows.
+
+@table @option
+
+@item box
+Used to draw a box around text using background color.
+Value should be either 1 (enable) or 0 (disable).
+The default value of @var{box} is 0.
+
+@item boxcolor
+The color to be used for drawing box around text.
+Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
+(e.g. "0xff00ff"), possibly followed by an alpha specifier.
+The default value of @var{boxcolor} is "white".
+
+@item draw
+Set an expression which specifies if the text should be drawn. If the
+expression evaluates to 0, the text is not drawn. This is useful for
+specifying that the text should be drawn only when specific conditions
+are met.
+
+Default value is "1".
+
+See below for the list of accepted constants and functions.
+
+@item expansion
+Select how the @var{text} is expanded. Can be either @code{none},
+@code{strftime} (deprecated) or
+@code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
+below for details.
+
+@item fix_bounds
+If true, check and fix text coords to avoid clipping.
+
+@item fontcolor
+The color to be used for drawing fonts.
+Either a string (e.g. "red") or in 0xRRGGBB[AA] format
+(e.g. "0xff000033"), possibly followed by an alpha specifier.
+The default value of @var{fontcolor} is "black".
+
+@item fontfile
+The font file to be used for drawing text. Path must be included.
+This parameter is mandatory.
+
+@item fontsize
+The font size to be used for drawing text.
+The default value of @var{fontsize} is 16.
+
+@item ft_load_flags
+Flags to be used for loading the fonts.
+
+The flags map the corresponding flags supported by libfreetype, and are
+a combination of the following values:
+@table @var
+@item default
+@item no_scale
+@item no_hinting
+@item render
+@item no_bitmap
+@item vertical_layout
+@item force_autohint
+@item crop_bitmap
+@item pedantic
+@item ignore_global_advance_width
+@item no_recurse
+@item ignore_transform
+@item monochrome
+@item linear_design
+@item no_autohint
+@item end table
+@end table
+
+Default value is "render".
+
+For more information consult the documentation for the FT_LOAD_*
+libfreetype flags.
+
+@item shadowcolor
+The color to be used for drawing a shadow behind the drawn text. It
+can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
The default value of @var{shadowcolor} is "black".
-@item ft_load_flags
-Flags to be used for loading the fonts.
+@item shadowx, shadowy
+The x and y offsets for the text shadow position with respect to the
+position of the text. They can be either positive or negative
+values. Default value for both is "0".
+
+@item tabsize
+The size in number of spaces to use for rendering the tab.
+Default value is 4.
+
+@item timecode
+Set the initial timecode representation in "hh:mm:ss[:;.]ff"
+format. It can be used with or without text parameter. @var{timecode_rate}
+option must be specified.
+
+@item timecode_rate, rate, r
+Set the timecode frame rate (timecode only).
+
+@item text
+The text string to be drawn. The text must be a sequence of UTF-8
+encoded characters.
+This parameter is mandatory if no file is specified with the parameter
+@var{textfile}.
+
+@item textfile
+A text file containing text to be drawn. The text must be a sequence
+of UTF-8 encoded characters.
+
+This parameter is mandatory if no text string is specified with the
+parameter @var{text}.
+
+If both @var{text} and @var{textfile} are specified, an error is thrown.
+
+@item reload
+If set to 1, the @var{textfile} will be reloaded before each frame.
+Be sure to update it atomically, or it may be read partially, or even fail.
+
+@item x, y
+The expressions which specify the offsets where text will be drawn
+within the video frame. They are relative to the top/left border of the
+output image.
+
+The default value of @var{x} and @var{y} is "0".
+
+See below for the list of accepted constants and functions.
+@end table
+
+The parameters for @var{x} and @var{y} are expressions containing the
+following constants and functions:
+
+@table @option
+@item dar
+input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
+
+@item hsub, vsub
+horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+
+@item line_h, lh
+the height of each text line
+
+@item main_h, h, H
+the input height
+
+@item main_w, w, W
+the input width
+
+@item max_glyph_a, ascent
+the maximum distance from the baseline to the highest/upper grid
+coordinate used to place a glyph outline point, for all the rendered
+glyphs.
+It is a positive value, due to the grid's orientation with the Y axis
+upwards.
+
+@item max_glyph_d, descent
+the maximum distance from the baseline to the lowest grid coordinate
+used to place a glyph outline point, for all the rendered glyphs.
+This is a negative value, due to the grid's orientation, with the Y axis
+upwards.
+
+@item max_glyph_h
+maximum glyph height, that is the maximum height for all the glyphs
+contained in the rendered text, it is equivalent to @var{ascent} -
+@var{descent}.
+
+@item max_glyph_w
+maximum glyph width, that is the maximum width for all the glyphs
+contained in the rendered text
+
+@item n
+the number of input frame, starting from 0
+
+@item rand(min, max)
+return a random number included between @var{min} and @var{max}
+
+@item sar
+input sample aspect ratio
+
+@item t
+timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+@item text_h, th
+the height of the rendered text
+
+@item text_w, tw
+the width of the rendered text
+
+@item x, y
+the x and y offset coordinates where the text is drawn.
+
+These parameters allow the @var{x} and @var{y} expressions to refer
+each other, so you can for example specify @code{y=x/dar}.
+@end table
+
+If libavfilter was built with @code{--enable-fontconfig}, then
+@option{fontfile} can be a fontconfig pattern or omitted.
+
+@anchor{drawtext_expansion}
+@subsection Text expansion
+
+If @option{expansion} is set to @code{strftime},
+the filter recognizes strftime() sequences in the provided text and
+expands them accordingly. Check the documentation of strftime(). This
+feature is deprecated.
+
+If @option{expansion} is set to @code{none}, the text is printed verbatim.
+
+If @option{expansion} is set to @code{normal} (which is the default),
+the following expansion mechanism is used.
+
+The backslash character '\', followed by any character, always expands to
+the second character.
+
+Sequence of the form @code{%@{...@}} are expanded. The text between the
+braces is a function name, possibly followed by arguments separated by ':'.
+If the arguments contain special characters or delimiters (':' or '@}'),
+they should be escaped.
+
+Note that they probably must also be escaped as the value for the
+@option{text} option in the filter argument string and as the filter
+argument in the filtergraph description, and possibly also for the shell,
+that makes up to four levels of escaping; using a text file avoids these
+problems.
+
+The following functions are available:
+
+@table @command
+
+@item expr, e
+The expression evaluation result.
+
+It must take one argument specifying the expression to be evaluated,
+which accepts the same constants and functions as the @var{x} and
+@var{y} values. Note that not all constants should be used, for
+example the text size is not known when evaluating the expression, so
+the constants @var{text_w} and @var{text_h} will have an undefined
+value.
+
+@item gmtime
+The time at which the filter is running, expressed in UTC.
+It can accept an argument: a strftime() format string.
+
+@item localtime
+The time at which the filter is running, expressed in the local time zone.
+It can accept an argument: a strftime() format string.
+
+@item n, frame_num
+The frame number, starting from 0.
+
+@item pts
+The timestamp of the current frame, in seconds, with microsecond accuracy.
+
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Draw "Test Text" with font FreeSerif, using the default values for the
+optional parameters.
+
+@example
+drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
+@end example
+
+@item
+Draw 'Test Text' with font FreeSerif of size 24 at position x=100
+and y=50 (counting from the top-left corner of the screen), text is
+yellow with a red box around it. Both the text and the box have an
+opacity of 20%.
+
+@example
+drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
+ x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
+@end example
+
+Note that the double quotes are not necessary if spaces are not used
+within the parameter list.
+
+@item
+Show the text at the center of the video frame:
+@example
+drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
+@end example
+
+@item
+Show a text line sliding from right to left in the last row of the video
+frame. The file @file{LONG_LINE} is assumed to contain a single line
+with no newlines.
+@example
+drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
+@end example
+
+@item
+Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
+@example
+drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
+@end example
+
+@item
+Draw a single green letter "g", at the center of the input video.
+The glyph baseline is placed at half screen height.
+@example
+drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
+@end example
+
+@item
+Show text for 1 second every 3 seconds:
+@example
+drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
+@end example
+
+@item
+Use fontconfig to set the font. Note that the colons need to be escaped.
+@example
+drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
+@end example
+
+@item
+Print the date of a real-time encoding (see strftime(3)):
+@example
+drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
+@end example
+
+@end itemize
+
+For more information about libfreetype, check:
+@url{http://www.freetype.org/}.
+
+For more information about fontconfig, check:
+@url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
+
+@section edgedetect
+
+Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
+
+This filter accepts the following optional named parameters:
+
+@table @option
+@item low, high
+Set low and high threshold values used by the Canny thresholding
+algorithm.
+
+The high threshold selects the "strong" edge pixels, which are then
+connected through 8-connectivity with the "weak" edge pixels selected
+by the low threshold.
+
+@var{low} and @var{high} threshold values must be choosen in the range
+[0,1], and @var{low} should be lesser or equal to @var{high}.
+
+Default value for @var{low} is @code{20/255}, and default value for @var{high}
+is @code{50/255}.
+@end table
+
+Example:
+@example
+edgedetect=low=0.1:high=0.4
+@end example
+
+@section fade
+
+Apply fade-in/out effect to input video.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+@var{type}:@var{start_frame}:@var{nb_frames}.
+
+A description of the accepted parameters follows.
+
+@table @option
+@item type, t
+Specify if the effect type, can be either @code{in} for fade-in, or
+@code{out} for a fade-out effect. Default is @code{in}.
+
+@item start_frame, s
+Specify the number of the start frame for starting to apply the fade
+effect. Default is 0.
+
+@item nb_frames, n
+Specify the number of frames for which the fade effect has to last. At
+the end of the fade-in effect the output video will have the same
+intensity as the input video, at the end of the fade-out transition
+the output video will be completely black. Default is 25.
+
+@item alpha
+If set to 1, fade only alpha channel, if one exists on the input.
+Default value is 0.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Fade in first 30 frames of video:
+@example
+fade=in:0:30
+@end example
+
+The command above is equivalent to:
+@example
+fade=t=in:s=0:n=30
+@end example
+
+@item
+Fade out last 45 frames of a 200-frame video:
+@example
+fade=out:155:45
+@end example
+
+@item
+Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
+@example
+fade=in:0:25, fade=out:975:25
+@end example
+
+@item
+Make first 5 frames black, then fade in from frame 5-24:
+@example
+fade=in:5:20
+@end example
+
+@item
+Fade in alpha over first 25 frames of video:
+@example
+fade=in:0:25:alpha=1
+@end example
+@end itemize
+
+@section field
+
+Extract a single field from an interlaced image using stride
+arithmetic to avoid wasting CPU time. The output frames are marked as
+non-interlaced.
+
+This filter accepts the following named options:
+@table @option
+@item type
+Specify whether to extract the top (if the value is @code{0} or
+@code{top}) or the bottom field (if the value is @code{1} or
+@code{bottom}).
+@end table
+
+If the option key is not specified, the first value sets the @var{type}
+option. For example:
+@example
+field=bottom
+@end example
+
+is equivalent to:
+@example
+field=type=bottom
+@end example
+
+@section fieldorder
+
+Transform the field order of the input video.
+
+This filter accepts the named option @option{order} which
+specifies the required field order that the input interlaced video
+will be transformed to. The option name can be omitted.
+
+The option @option{order} can assume one of the following values:
+@table @samp
+@item bff
+output bottom field first
+@item tff
+output top field first
+@end table
+
+Default value is @samp{tff}.
+
+Transformation is achieved by shifting the picture content up or down
+by one line, and filling the remaining line with appropriate picture content.
+This method is consistent with most broadcast field order converters.
+
+If the input video is not flagged as being interlaced, or it is already
+flagged as being of the required output field order then this filter does
+not alter the incoming video.
+
+This filter is very useful when converting to or from PAL DV material,
+which is bottom field first.
+
+For example:
+@example
+ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
+@end example
+
+@section fifo
+
+Buffer input images and send them when they are requested.
+
+This filter is mainly useful when auto-inserted by the libavfilter
+framework.
+
+The filter does not take parameters.
+
+@anchor{format}
+@section format
+
+Convert the input video to one of the specified pixel formats.
+Libavfilter will try to pick one that is supported for the input to
+the next filter.
+
+This filter accepts the following parameters:
+@table @option
+
+@item pix_fmts
+A '|'-separated list of pixel format names, for example
+"pix_fmts=yuv420p|monow|rgb24".
+
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Convert the input video to the format @var{yuv420p}
+@example
+format=pix_fmts=yuv420p
+@end example
+
+Convert the input video to any of the formats in the list
+@example
+format=pix_fmts=yuv420p|yuv444p|yuv410p
+@end example
+@end itemize
+
+@section fps
+
+Convert the video to specified constant frame rate by duplicating or dropping
+frames as necessary.
+
+This filter accepts the following named parameters:
+@table @option
+
+@item fps
+Desired output frame rate. The default is @code{25}.
+
+@item round
+Rounding method.
+
+Possible values are:
+@table @option
+@item zero
+zero round towards 0
+@item inf
+round away from 0
+@item down
+round towards -infinity
+@item up
+round towards +infinity
+@item near
+round to nearest
+@end table
+The default is @code{near}.
+
+@end table
+
+Alternatively, the options can be specified as a flat string:
+@var{fps}[:@var{round}].
+
+See also the @ref{setpts} filter.
+
+@section framestep
+
+Select one frame every N.
+
+This filter accepts in input a string representing a positive
+integer. Default argument is @code{1}.
+
+@anchor{frei0r}
+@section frei0r
+
+Apply a frei0r effect to the input video.
+
+To enable compilation of this filter you need to install the frei0r
+header and configure FFmpeg with @code{--enable-frei0r}.
+
+The filter supports the syntax:
+@example
+@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
+@end example
+
+@var{filter_name} is the name of the frei0r effect to load. If the
+environment variable @env{FREI0R_PATH} is defined, the frei0r effect
+is searched in each one of the directories specified by the colon (or
+semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
+otherwise in the standard frei0r paths, which are in this order:
+@file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
+@file{/usr/lib/frei0r-1/}.
+
+@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
+for the frei0r effect.
+
+A frei0r effect parameter can be a boolean (whose values are specified
+with "y" and "n"), a double, a color (specified by the syntax
+@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
+numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
+description), a position (specified by the syntax @var{X}/@var{Y},
+@var{X} and @var{Y} being float numbers) and a string.
+
+The number and kind of parameters depend on the loaded effect. If an
+effect parameter is not specified the default value is set.
+
+@subsection Examples
+
+@itemize
+@item
+Apply the distort0r effect, set the first two double parameters:
+@example
+frei0r=distort0r:0.5:0.01
+@end example
+
+@item
+Apply the colordistance effect, take a color as first parameter:
+@example
+frei0r=colordistance:0.2/0.3/0.4
+frei0r=colordistance:violet
+frei0r=colordistance:0x112233
+@end example
+
+@item
+Apply the perspective effect, specify the top left and top right image
+positions:
+@example
+frei0r=perspective:0.2/0.2:0.8/0.2
+@end example
+@end itemize
+
+For more information see:
+@url{http://frei0r.dyne.org}
+
+@section geq
+
+The filter takes one, two, three or four equations as parameter, separated by ':'.
+The first equation is mandatory and applies to the luma plane. The two
+following are respectively for chroma blue and chroma red planes.
+
+The filter syntax allows named parameters:
+
+@table @option
+@item lum_expr
+the luminance expression
+@item cb_expr
+the chrominance blue expression
+@item cr_expr
+the chrominance red expression
+@item alpha_expr
+the alpha expression
+@end table
+
+If one of the chrominance expression is not defined, it falls back on the other
+one. If no alpha expression is specified it will evaluate to opaque value.
+If none of chrominance expressions are
+specified, they will evaluate the luminance expression.
+
+The expressions can use the following variables and functions:
+
+@table @option
+@item N
+The sequential number of the filtered frame, starting from @code{0}.
+
+@item X
+@item Y
+The coordinates of the current sample.
+
+@item W
+@item H
+The width and height of the image.
+
+@item SW
+@item SH
+Width and height scale depending on the currently filtered plane. It is the
+ratio between the corresponding luma plane number of pixels and the current
+plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
+@code{0.5,0.5} for chroma planes.
+
+@item T
+Time of the current frame, expressed in seconds.
+
+@item p(x, y)
+Return the value of the pixel at location (@var{x},@var{y}) of the current
+plane.
+
+@item lum(x, y)
+Return the value of the pixel at location (@var{x},@var{y}) of the luminance
+plane.
+
+@item cb(x, y)
+Return the value of the pixel at location (@var{x},@var{y}) of the
+blue-difference chroma plane. Returns 0 if there is no such plane.
+
+@item cr(x, y)
+Return the value of the pixel at location (@var{x},@var{y}) of the
+red-difference chroma plane. Returns 0 if there is no such plane.
+
+@item alpha(x, y)
+Return the value of the pixel at location (@var{x},@var{y}) of the alpha
+plane. Returns 0 if there is no such plane.
+@end table
+
+For functions, if @var{x} and @var{y} are outside the area, the value will be
+automatically clipped to the closer edge.
+
+@subsection Examples
+
+@itemize
+@item
+Flip the image horizontally:
+@example
+geq=p(W-X\,Y)
+@end example
+
+@item
+Generate a bidimensional sine wave, with angle @code{PI/3} and a
+wavelength of 100 pixels:
+@example
+geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
+@end example
+
+@item
+Generate a fancy enigmatic moving light:
+@example
+nullsrc=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128
+@end example
+@end itemize
+
+@section gradfun
+
+Fix the banding artifacts that are sometimes introduced into nearly flat
+regions by truncation to 8bit color depth.
+Interpolate the gradients that should go where the bands are, and
+dither them.
+
+This filter is designed for playback only. Do not use it prior to
+lossy compression, because compression tends to lose the dither and
+bring back the bands.
+
+The filter accepts a list of options in the form of @var{key}=@var{value} pairs
+separated by ":". A description of the accepted options follows.
+
+@table @option
+
+@item strength
+The maximum amount by which the filter will change
+any one pixel. Also the threshold for detecting nearly flat
+regions. Acceptable values range from @code{0.51} to @code{64}, default value
+is @code{1.2}.
+
+@item radius
+The neighborhood to fit the gradient to. A larger
+radius makes for smoother gradients, but also prevents the filter from
+modifying the pixels near detailed regions. Acceptable values are
+@code{8-32}, default value is @code{16}.
+
+@end table
+
+Alternatively, the options can be specified as a flat string:
+@var{strength}[:@var{radius}]
+
+@subsection Examples
+
+@itemize
+@item
+Apply the filter with a @code{3.5} strength and radius of @code{8}:
+@example
+gradfun=3.5:8
+@end example
+
+@item
+Specify radius, omitting the strength (which will fall-back to the default
+value):
+@example
+gradfun=radius=8
+@end example
+
+@end itemize
+
+@section hflip
+
+Flip the input video horizontally.
+
+For example to horizontally flip the input video with @command{ffmpeg}:
+@example
+ffmpeg -i in.avi -vf "hflip" out.avi
+@end example
+
+@section histeq
+This filter applies a global color histogram equalization on a
+per-frame basis.
+
+It can be used to correct video that has a compressed range of pixel
+intensities. The filter redistributes the pixel intensities to
+equalize their distribution across the intensity range. It may be
+viewed as an "automatically adjusting contrast filter". This filter is
+useful only for correcting degraded or poorly captured source
+video.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to syntax
+@var{strength}:@var{intensity}:@var{antibanding}.
+
+This filter accepts the following named options:
+
+@table @option
+@item strength
+Determine the amount of equalization to be applied. As the strength
+is reduced, the distribution of pixel intensities more-and-more
+approaches that of the input frame. The value must be a float number
+in the range [0,1] and defaults to 0.200.
+
+@item intensity
+Set the maximum intensity that can generated and scale the output
+values appropriately. The strength should be set as desired and then
+the intensity can be limited if needed to avoid washing-out. The value
+must be a float number in the range [0,1] and defaults to 0.210.
+
+@item antibanding
+Set the antibanding level. If enabled the filter will randomly vary
+the luminance of output pixels by a small amount to avoid banding of
+the histogram. Possible values are @code{none}, @code{weak} or
+@code{strong}. It defaults to @code{none}.
+@end table
+
+@section histogram
+
+Compute and draw a color distribution histogram for the input video.
+
+The computed histogram is a representation of distribution of color components
+in an image.
+
+The filter accepts the following named parameters:
+
+@table @option
+@item mode
+Set histogram mode.
+
+It accepts the following values:
+@table @samp
+@item levels
+standard histogram that display color components distribution in an image.
+Displays color graph for each color component. Shows distribution
+of the Y, U, V, A or G, B, R components, depending on input format,
+in current frame. Bellow each graph is color component scale meter.
+
+@item color
+chroma values in vectorscope, if brighter more such chroma values are
+distributed in an image.
+Displays chroma values (U/V color placement) in two dimensional graph
+(which is called a vectorscope). It can be used to read of the hue and
+saturation of the current frame. At a same time it is a histogram.
+The whiter a pixel in the vectorscope, the more pixels of the input frame
+correspond to that pixel (that is the more pixels have this chroma value).
+The V component is displayed on the horizontal (X) axis, with the leftmost
+side being V = 0 and the rightmost side being V = 255.
+The U component is displayed on the vertical (Y) axis, with the top
+representing U = 0 and the bottom representing U = 255.
+
+The position of a white pixel in the graph corresponds to the chroma value
+of a pixel of the input clip. So the graph can be used to read of the
+hue (color flavor) and the saturation (the dominance of the hue in the color).
+As the hue of a color changes, it moves around the square. At the center of
+the square, the saturation is zero, which means that the corresponding pixel
+has no color. If you increase the amount of a specific color, while leaving
+the other colors unchanged, the saturation increases, and you move towards
+the edge of the square.
+
+@item color2
+chroma values in vectorscope, similar as @code{color} but actual chroma values
+are displayed.
+
+@item waveform
+per row/column color component graph. In row mode graph in the left side represents
+color component value 0 and right side represents value = 255. In column mode top
+side represents color component value = 0 and bottom side represents value = 255.
+@end table
+Default value is @code{levels}.
+
+@item level_height
+Set height of level in @code{levels}. Default value is @code{200}.
+Allowed range is [50, 2048].
+
+@item scale_height
+Set height of color scale in @code{levels}. Default value is @code{12}.
+Allowed range is [0, 40].
+
+@item step
+Set step for @code{waveform} mode. Smaller values are useful to find out how much
+of same luminance values across input rows/columns are distributed.
+Default value is @code{10}. Allowed range is [1, 255].
+
+@item waveform_mode
+Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
+Default is @code{row}.
+
+@item display_mode
+Set display mode for @code{waveform} and @code{levels}.
+It accepts the following values:
+@table @samp
+@item parade
+Display separate graph for the color components side by side in
+@code{row} waveform mode or one below other in @code{column} waveform mode
+for @code{waveform} histogram mode. For @code{levels} histogram mode
+per color component graphs are placed one bellow other.
+
+This display mode in @code{waveform} histogram mode makes it easy to spot
+color casts in the highlights and shadows of an image, by comparing the
+contours of the top and the bottom of each waveform.
+Since whites, grays, and blacks are characterized by
+exactly equal amounts of red, green, and blue, neutral areas of the
+picture should display three waveforms of roughly equal width/height.
+If not, the correction is easy to make by making adjustments to level the
+three waveforms.
+
+@item overlay
+Presents information that's identical to that in the @code{parade}, except
+that the graphs representing color components are superimposed directly
+over one another.
+
+This display mode in @code{waveform} histogram mode can make it easier to spot
+the relative differences or similarities in overlapping areas of the color
+components that are supposed to be identical, such as neutral whites, grays,
+or blacks.
+@end table
+Default is @code{parade}.
+@end table
+
+@subsection Examples
+
+@itemize
+
+@item
+Calculate and draw histogram:
+@example
+ffplay -i input -vf histogram
+@end example
+
+@end itemize
+
+@section hqdn3d
+
+High precision/quality 3d denoise filter. This filter aims to reduce
+image noise producing smooth images and making still images really
+still. It should enhance compressibility.
+
+It accepts the following optional parameters:
+@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
+
+@table @option
+@item luma_spatial
+a non-negative float number which specifies spatial luma strength,
+defaults to 4.0
+
+@item chroma_spatial
+a non-negative float number which specifies spatial chroma strength,
+defaults to 3.0*@var{luma_spatial}/4.0
+
+@item luma_tmp
+a float number which specifies luma temporal strength, defaults to
+6.0*@var{luma_spatial}/4.0
+
+@item chroma_tmp
+a float number which specifies chroma temporal strength, defaults to
+@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
+@end table
+
+@section hue
+
+Modify the hue and/or the saturation of the input.
+
+This filter accepts the following optional named options:
+
+@table @option
+@item h
+Specify the hue angle as a number of degrees. It accepts a float
+number or an expression, and defaults to 0.0.
+
+@item H
+Specify the hue angle as a number of radians. It accepts a float
+number or an expression, and defaults to 0.0.
+
+@item s
+Specify the saturation in the [-10,10] range. It accepts a float number and
+defaults to 1.0.
+@end table
+
+The @var{h}, @var{H} and @var{s} parameters are expressions containing the
+following constants:
+
+@table @option
+@item n
+frame count of the input frame starting from 0
+
+@item pts
+presentation timestamp of the input frame expressed in time base units
+
+@item r
+frame rate of the input video, NAN if the input frame rate is unknown
+
+@item t
+timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+@item tb
+time base of the input video
+@end table
+
+The options can also be set using the syntax: @var{hue}:@var{saturation}
+
+In this case @var{hue} is expressed in degrees.
+
+@subsection Examples
+
+@itemize
+@item
+Set the hue to 90 degrees and the saturation to 1.0:
+@example
+hue=h=90:s=1
+@end example
+
+@item
+Same command but expressing the hue in radians:
+@example
+hue=H=PI/2:s=1
+@end example
+
+@item
+Same command without named options, hue must be expressed in degrees:
+@example
+hue=90:1
+@end example
+
+@item
+Note that "h:s" syntax does not support expressions for the values of
+h and s, so the following example will issue an error:
+@example
+hue=PI/2:1
+@end example
+
+@item
+Rotate hue and make the saturation swing between 0
+and 2 over a period of 1 second:
+@example
+hue="H=2*PI*t: s=sin(2*PI*t)+1"
+@end example
+
+@item
+Apply a 3 seconds saturation fade-in effect starting at 0:
+@example
+hue="s=min(t/3\,1)"
+@end example
+
+The general fade-in expression can be written as:
+@example
+hue="s=min(0\, max((t-START)/DURATION\, 1))"
+@end example
+
+@item
+Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
+@example
+hue="s=max(0\, min(1\, (8-t)/3))"
+@end example
+
+The general fade-out expression can be written as:
+@example
+hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
+@end example
+
+@end itemize
+
+@subsection Commands
+
+This filter supports the following command:
+@table @option
+@item reinit
+Modify the hue and/or the saturation of the input video.
+The command accepts the same named options and syntax than when calling the
+filter from the command-line.
+
+If a parameter is omitted, it is kept at its current value.
+@end table
+
+@section idet
+
+Detect video interlacing type.
+
+This filter tries to detect if the input is interlaced or progressive,
+top or bottom field first.
+
+@section il
+
+Deinterleave or interleave fields.
+
+This filter allows to process interlaced images fields without
+deinterlacing them. Deinterleaving splits the input frame into 2
+fields (so called half pictures). Odd lines are moved to the top
+half of the output image, even lines to the bottom half.
+You can process (filter) them independently and then re-interleave them.
+
+It accepts a list of options in the form of @var{key}=@var{value} pairs
+separated by ":". A description of the accepted options follows.
+
+@table @option
+@item luma_mode, l
+@item chroma_mode, s
+@item alpha_mode, a
+Available values for @var{luma_mode}, @var{chroma_mode} and
+@var{alpha_mode} are:
+
+@table @samp
+@item none
+Do nothing.
+
+@item deinterleave, d
+Deinterleave fields, placing one above the other.
+
+@item interleave, i
+Interleave fields. Reverse the effect of deinterleaving.
+@end table
+Default value is @code{none}.
+
+@item luma_swap, ls
+@item chroma_swap, cs
+@item alpha_swap, as
+Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
+@end table
+
+@section kerndeint
+
+Deinterlace input video by applying Donald Graft's adaptive kernel
+deinterling. Work on interlaced parts of a video to produce
+progressive frames.
+
+This filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the following syntax:
+@var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
+
+The description of the accepted parameters follows.
+
+@table @option
+@item thresh
+Set the threshold which affects the filter's tolerance when
+determining if a pixel line must be processed. It must be an integer
+in the range [0,255] and defaults to 10. A value of 0 will result in
+applying the process on every pixels.
+
+@item map
+Paint pixels exceeding the threshold value to white if set to 1.
+Default is 0.
+
+@item order
+Set the fields order. Swap fields if set to 1, leave fields alone if
+0. Default is 0.
+
+@item sharp
+Enable additional sharpening if set to 1. Default is 0.
+
+@item twoway
+Enable twoway sharpening if set to 1. Default is 0.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Apply default values:
+@example
+kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
+@end example
+
+@item
+Enable additional sharpening:
+@example
+kerndeint=sharp=1
+@end example
+
+@item
+Paint processed pixels in white:
+@example
+kerndeint=map=1
+@end example
+@end itemize
+
+@section lut, lutrgb, lutyuv
+
+Compute a look-up table for binding each pixel component input value
+to an output value, and apply it to input video.
+
+@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
+to an RGB input video.
+
+These filters accept in input a ":"-separated list of options, which
+specify the expressions used for computing the lookup table for the
+corresponding pixel component values.
+
+The @var{lut} filter requires either YUV or RGB pixel formats in
+input, and accepts the options:
+@table @option
+@item c0
+set first pixel component expression
+@item c1
+set second pixel component expression
+@item c2
+set third pixel component expression
+@item c3
+set fourth pixel component expression, corresponds to the alpha component
+@end table
+
+The exact component associated to each option depends on the format in
+input.
+
+The @var{lutrgb} filter requires RGB pixel formats in input, and
+accepts the options:
+@table @option
+@item r
+set red component expression
+@item g
+set green component expression
+@item b
+set blue component expression
+@item a
+alpha component expression
+@end table
+
+The @var{lutyuv} filter requires YUV pixel formats in input, and
+accepts the options:
+@table @option
+@item y
+set Y/luminance component expression
+@item u
+set U/Cb component expression
+@item v
+set V/Cr component expression
+@item a
+set alpha component expression
+@end table
+
+The expressions can contain the following constants and functions:
+
+@table @option
+@item w, h
+the input width and height
+
+@item val
+input value for the pixel component
+
+@item clipval
+the input value clipped in the @var{minval}-@var{maxval} range
+
+@item maxval
+maximum value for the pixel component
+
+@item minval
+minimum value for the pixel component
+
+@item negval
+the negated value for the pixel component value clipped in the
+@var{minval}-@var{maxval} range , it corresponds to the expression
+"maxval-clipval+minval"
+
+@item clip(val)
+the computed value in @var{val} clipped in the
+@var{minval}-@var{maxval} range
+
+@item gammaval(gamma)
+the computed gamma correction value of the pixel component value
+clipped in the @var{minval}-@var{maxval} range, corresponds to the
+expression
+"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
+
+@end table
+
+All expressions default to "val".
+
+@subsection Examples
+
+@itemize
+@item
+Negate input video:
+@example
+lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
+lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
+@end example
+
+The above is the same as:
+@example
+lutrgb="r=negval:g=negval:b=negval"
+lutyuv="y=negval:u=negval:v=negval"
+@end example
+
+@item
+Negate luminance:
+@example
+lutyuv=y=negval
+@end example
+
+@item
+Remove chroma components, turns the video into a graytone image:
+@example
+lutyuv="u=128:v=128"
+@end example
+
+@item
+Apply a luma burning effect:
+@example
+lutyuv="y=2*val"
+@end example
+
+@item
+Remove green and blue components:
+@example
+lutrgb="g=0:b=0"
+@end example
+
+@item
+Set a constant alpha channel value on input:
+@example
+format=rgba,lutrgb=a="maxval-minval/2"
+@end example
+
+@item
+Correct luminance gamma by a 0.5 factor:
+@example
+lutyuv=y=gammaval(0.5)
+@end example
+
+@item
+Discard least significant bits of luma:
+@example
+lutyuv=y='bitand(val, 128+64+32)'
+@end example
+@end itemize
+
+@section mp
+
+Apply an MPlayer filter to the input video.
+
+This filter provides a wrapper around most of the filters of
+MPlayer/MEncoder.
+
+This wrapper is considered experimental. Some of the wrapped filters
+may not work properly and we may drop support for them, as they will
+be implemented natively into FFmpeg. Thus you should avoid
+depending on them when writing portable scripts.
+
+The filters accepts the parameters:
+@var{filter_name}[:=]@var{filter_params}
+
+@var{filter_name} is the name of a supported MPlayer filter,
+@var{filter_params} is a string containing the parameters accepted by
+the named filter.
+
+The list of the currently supported filters follows:
+@table @var
+@item detc
+@item dint
+@item divtc
+@item down3dright
+@item eq2
+@item eq
+@item fil
+@item fspp
+@item ilpack
+@item ivtc
+@item mcdeint
+@item ow
+@item perspective
+@item phase
+@item pp7
+@item pullup
+@item qp
+@item sab
+@item softpulldown
+@item spp
+@item telecine
+@item tinterlace
+@item uspp
+@end table
+
+The parameter syntax and behavior for the listed filters are the same
+of the corresponding MPlayer filters. For detailed instructions check
+the "VIDEO FILTERS" section in the MPlayer manual.
+
+@subsection Examples
+
+@itemize
+@item
+Adjust gamma, brightness, contrast:
+@example
+mp=eq2=1.0:2:0.5
+@end example
+@end itemize
+
+See also mplayer(1), @url{http://www.mplayerhq.hu/}.
+
+@section negate
+
+Negate input video.
+
+This filter accepts an integer in input, if non-zero it negates the
+alpha component (if available). The default value in input is 0.
+
+@section noformat
+
+Force libavfilter not to use any of the specified pixel formats for the
+input to the next filter.
+
+This filter accepts the following parameters:
+@table @option
+
+@item pix_fmts
+A '|'-separated list of pixel format names, for example
+"pix_fmts=yuv420p|monow|rgb24".
+
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Force libavfilter to use a format different from @var{yuv420p} for the
+input to the vflip filter:
+@example
+noformat=pix_fmts=yuv420p,vflip
+@end example
+
+@item
+Convert the input video to any of the formats not contained in the list:
+@example
+noformat=yuv420p|yuv444p|yuv410p
+@end example
+@end itemize
+
+@section noise
+
+Add noise on video input frame.
+
+This filter accepts a list of options in the form of @var{key}=@var{value}
+pairs separated by ":". A description of the accepted options follows.
+
+@table @option
+@item all_seed
+@item c0_seed
+@item c1_seed
+@item c2_seed
+@item c3_seed
+Set noise seed for specific pixel component or all pixel components in case
+of @var{all_seed}. Default value is @code{123457}.
+
+@item all_strength, alls
+@item c0_strength, c0s
+@item c1_strength, c1s
+@item c2_strength, c2s
+@item c3_strength, c3s
+Set noise strength for specific pixel component or all pixel components in case
+@var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
+
+@item all_flags, allf
+@item c0_flags, c0f
+@item c1_flags, c1f
+@item c2_flags, c2f
+@item c3_flags, c3f
+Set pixel component flags or set flags for all components if @var{all_flags}.
+Available values for component flags are:
+@table @samp
+@item a
+averaged temporal noise (smoother)
+@item p
+mix random noise with a (semi)regular pattern
+@item q
+higher quality (slightly better looking, slightly slower)
+@item t
+temporal noise (noise pattern changes between frames)
+@item u
+uniform noise (gaussian otherwise)
+@end table
+@end table
+
+@subsection Examples
+
+Add temporal and uniform noise to input video:
+@example
+noise=alls=20:allf=t+u
+@end example
+
+@section null
+
+Pass the video source unchanged to the output.
+
+@section ocv
+
+Apply video transform using libopencv.
+
+To enable this filter install libopencv library and headers and
+configure FFmpeg with @code{--enable-libopencv}.
+
+The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
+
+@var{filter_name} is the name of the libopencv filter to apply.
+
+@var{filter_params} specifies the parameters to pass to the libopencv
+filter. If not specified the default values are assumed.
+
+Refer to the official libopencv documentation for more precise
+information:
+@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
+
+Follows the list of supported libopencv filters.
+
+@anchor{dilate}
+@subsection dilate
+
+Dilate an image by using a specific structuring element.
+This filter corresponds to the libopencv function @code{cvDilate}.
+
+It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
+
+@var{struct_el} represents a structuring element, and has the syntax:
+@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
+
+@var{cols} and @var{rows} represent the number of columns and rows of
+the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
+point, and @var{shape} the shape for the structuring element, and
+can be one of the values "rect", "cross", "ellipse", "custom".
+
+If the value for @var{shape} is "custom", it must be followed by a
+string of the form "=@var{filename}". The file with name
+@var{filename} is assumed to represent a binary image, with each
+printable character corresponding to a bright pixel. When a custom
+@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
+or columns and rows of the read file are assumed instead.
+
+The default value for @var{struct_el} is "3x3+0x0/rect".
+
+@var{nb_iterations} specifies the number of times the transform is
+applied to the image, and defaults to 1.
+
+Follow some example:
+@example
+# use the default values
+ocv=dilate
+
+# dilate using a structuring element with a 5x5 cross, iterate two times
+ocv=dilate=5x5+2x2/cross:2
+
+# read the shape from the file diamond.shape, iterate two times
+# the file diamond.shape may contain a pattern of characters like this:
+# *
+# ***
+# *****
+# ***
+# *
+# the specified cols and rows are ignored (but not the anchor point coordinates)
+ocv=0x0+2x2/custom=diamond.shape:2
+@end example
+
+@subsection erode
+
+Erode an image by using a specific structuring element.
+This filter corresponds to the libopencv function @code{cvErode}.
+
+The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
+with the same syntax and semantics as the @ref{dilate} filter.
+
+@subsection smooth
+
+Smooth the input video.
+
+The filter takes the following parameters:
+@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
+
+@var{type} is the type of smooth filter to apply, and can be one of
+the following values: "blur", "blur_no_scale", "median", "gaussian",
+"bilateral". The default value is "gaussian".
+
+@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
+parameters whose meanings depend on smooth type. @var{param1} and
+@var{param2} accept integer positive values or 0, @var{param3} and
+@var{param4} accept float values.
+
+The default value for @var{param1} is 3, the default value for the
+other parameters is 0.
+
+These parameters correspond to the parameters assigned to the
+libopencv function @code{cvSmooth}.
+
+@anchor{overlay}
+@section overlay
+
+Overlay one video on top of another.
+
+It takes two inputs and one output, the first input is the "main"
+video on which the second input is overlayed.
+
+This filter accepts a list of @var{key}=@var{value} pairs as argument,
+separated by ":". If the key of the first options is omitted, the
+arguments are interpreted according to the syntax @var{x}:@var{y}.
+
+A description of the accepted options follows.
+
+@table @option
+@item x
+@item y
+Set the expression for the x and y coordinates of the overlayed video
+on the main video. Default value is "0" for both expressions. In case
+the expression is invalid, it is set to a huge value (meaning that the
+overlay will not be displayed within the output visible area).
+
+@item enable
+Set the expression which enables the overlay. If the evaluation is
+different from 0, the overlay is displayed on top of the input
+frame. By default it is "1".
+
+@item eval
+Set when the expressions for @option{x}, @option{y}, and
+@option{enable} are evaluated.
+
+It accepts the following values:
+@table @samp
+@item init
+only evaluate expressions once during the filter initialization or
+when a command is processed
+
+@item frame
+evaluate expressions for each incoming frame
+@end table
+
+Default value is @samp{frame}.
+
+@item shortest
+If set to 1, force the output to terminate when the shortest input
+terminates. Default value is 0.
+
+@item format
+Set the format for the output video.
+
+It accepts the following values:
+@table @samp
+@item yuv420
+force YUV420 output
+
+@item yuv444
+force YUV444 output
+
+@item rgb
+force RGB output
+@end table
+
+Default value is @samp{yuv420}.
+
+@item rgb @emph{(deprecated)}
+If set to 1, force the filter to accept inputs in the RGB
+color space. Default value is 0. This option is deprecated, use
+@option{format} instead.
+@end table
+
+The @option{x}, @option{y}, and @option{enable} expressions can
+contain the following parameters.
+
+@table @option
+@item main_w, W
+@item main_h, H
+main input width and height
+
+@item overlay_w, w
+@item overlay_h, h
+overlay input width and height
+
+@item x
+@item y
+the computed values for @var{x} and @var{y}. They are evaluated for
+each new frame.
+
+@item hsub
+@item vsub
+horizontal and vertical chroma subsample values of the output
+format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
+@var{vsub} is 1.
+
+@item n
+the number of input frame, starting from 0
+
+@item pos
+the position in the file of the input frame, NAN if unknown
+
+@item t
+timestamp expressed in seconds, NAN if the input timestamp is unknown
+@end table
+
+Note that the @var{n}, @var{pos}, @var{t} variables are available only
+when evaluation is done @emph{per frame}, and will evaluate to NAN
+when @option{eval} is set to @samp{init}.
+
+Be aware that frames are taken from each input video in timestamp
+order, hence, if their initial timestamps differ, it is a a good idea
+to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
+have them begin in the same zero timestamp, as it does the example for
+the @var{movie} filter.
+
+You can chain together more overlays but you should test the
+efficiency of such approach.
+
+@subsection Commands
+
+This filter supports the following command:
+@table @option
+@item x
+Set the @option{x} option expression.
+
+@item y
+Set the @option{y} option expression.
+
+@item enable
+Set the @option{enable} option expression.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Draw the overlay at 10 pixels from the bottom right corner of the main
+video:
+@example
+overlay=main_w-overlay_w-10:main_h-overlay_h-10
+@end example
+
+Using named options the example above becomes:
+@example
+overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
+@end example
+
+@item
+Insert a transparent PNG logo in the bottom left corner of the input,
+using the @command{ffmpeg} tool with the @code{-filter_complex} option:
+@example
+ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
+@end example
+
+@item
+Insert 2 different transparent PNG logos (second logo on bottom
+right corner) using the @command{ffmpeg} tool:
+@example
+ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
+@end example
+
+@item
+Add a transparent color layer on top of the main video, @code{WxH}
+must specify the size of the main input to the overlay filter:
+@example
+color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
+@end example
+
+@item
+Play an original video and a filtered version (here with the deshake
+filter) side by side using the @command{ffplay} tool:
+@example
+ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
+@end example
+
+The above command is the same as:
+@example
+ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
+@end example
+
+@item
+Make a sliding overlay appearing from the left to the right top part of the
+screen starting since time 2:
+@example
+overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
+@end example
+
+@item
+Compose output by putting two input videos side to side:
+@example
+ffmpeg -i left.avi -i right.avi -filter_complex "
+nullsrc=size=200x100 [background];
+[0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
+[1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
+[background][left] overlay=shortest=1 [background+left];
+[background+left][right] overlay=shortest=1:x=100 [left+right]
+"
+@end example
+
+@item
+Chain several overlays in cascade:
+@example
+nullsrc=s=200x200 [bg];
+testsrc=s=100x100, split=4 [in0][in1][in2][in3];
+[in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
+[in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
+[in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
+[in3] null, [mid2] overlay=100:100 [out0]
+@end example
+
+@end itemize
+
+@section pad
+
+Add paddings to the input image, and place the original input at the
+given coordinates @var{x}, @var{y}.
+
+The filter accepts parameters as a list of @var{key}=@var{value} pairs,
+separated by ":".
+
+If the key of the first options is omitted, the arguments are
+interpreted according to the syntax
+@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
+
+A description of the accepted options follows.
+
+@table @option
+@item width, w
+@item height, h
+Specify an expression for the size of the output image with the
+paddings added. If the value for @var{width} or @var{height} is 0, the
+corresponding input size is used for the output.
+
+The @var{width} expression can reference the value set by the
+@var{height} expression, and vice versa.
+
+The default value of @var{width} and @var{height} is 0.
+
+@item x
+@item y
+Specify an expression for the offsets where to place the input image
+in the padded area with respect to the top/left border of the output
+image.
+
+The @var{x} expression can reference the value set by the @var{y}
+expression, and vice versa.
+
+The default value of @var{x} and @var{y} is 0.
+
+@item color
+Specify the color of the padded area, it can be the name of a color
+(case insensitive match) or a 0xRRGGBB[AA] sequence.
+
+The default value of @var{color} is "black".
+@end table
+
+The value for the @var{width}, @var{height}, @var{x}, and @var{y}
+options are expressions containing the following constants:
+
+@table @option
+@item in_w, in_h
+the input video width and height
+
+@item iw, ih
+same as @var{in_w} and @var{in_h}
+
+@item out_w, out_h
+the output width and height, that is the size of the padded area as
+specified by the @var{width} and @var{height} expressions
+
+@item ow, oh
+same as @var{out_w} and @var{out_h}
+
+@item x, y
+x and y offsets as specified by the @var{x} and @var{y}
+expressions, or NAN if not yet specified
+
+@item a
+same as @var{iw} / @var{ih}
+
+@item sar
+input sample aspect ratio
+
+@item dar
+input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
+
+@item hsub, vsub
+horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Add paddings with color "violet" to the input video. Output video
+size is 640x480, the top-left corner of the input video is placed at
+column 0, row 40:
+@example
+pad=640:480:0:40:violet
+@end example
+
+The example above is equivalent to the following command:
+@example
+pad=width=640:height=480:x=0:y=40:color=violet
+@end example
+
+@item
+Pad the input to get an output with dimensions increased by 3/2,
+and put the input video at the center of the padded area:
+@example
+pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
+@end example
+
+@item
+Pad the input to get a squared output with size equal to the maximum
+value between the input width and height, and put the input video at
+the center of the padded area:
+@example
+pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
+@end example
+
+@item
+Pad the input to get a final w/h ratio of 16:9:
+@example
+pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
+@end example
+
+@item
+In case of anamorphic video, in order to set the output display aspect
+correctly, it is necessary to use @var{sar} in the expression,
+according to the relation:
+@example
+(ih * X / ih) * sar = output_dar
+X = output_dar / sar
+@end example
+
+Thus the previous example needs to be modified to:
+@example
+pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
+@end example
+
+@item
+Double output size and put the input video in the bottom-right
+corner of the output padded area:
+@example
+pad="2*iw:2*ih:ow-iw:oh-ih"
+@end example
+@end itemize
+
+@section pixdesctest
+
+Pixel format descriptor test filter, mainly useful for internal
+testing. The output video should be equal to the input video.
+
+For example:
+@example
+format=monow, pixdesctest
+@end example
+
+can be used to test the monowhite pixel format descriptor definition.
+
+@section pp
+
+Enable the specified chain of postprocessing subfilters using libpostproc. This
+library should be automatically selected with a GPL build (@code{--enable-gpl}).
+Subfilters must be separated by '/' and can be disabled by prepending a '-'.
+Each subfilter and some options have a short and a long name that can be used
+interchangeably, i.e. dr/dering are the same.
+
+All subfilters share common options to determine their scope:
+
+@table @option
+@item a/autoq
+Honor the quality commands for this subfilter.
+
+@item c/chrom
+Do chrominance filtering, too (default).
+
+@item y/nochrom
+Do luminance filtering only (no chrominance).
+
+@item n/noluma
+Do chrominance filtering only (no luminance).
+@end table
+
+These options can be appended after the subfilter name, separated by a ':'.
+
+Available subfilters are:
+
+@table @option
+@item hb/hdeblock[:difference[:flatness]]
+Horizontal deblocking filter
+@table @option
+@item difference
+Difference factor where higher values mean more deblocking (default: @code{32}).
+@item flatness
+Flatness threshold where lower values mean more deblocking (default: @code{39}).
+@end table
+
+@item vb/vdeblock[:difference[:flatness]]
+Vertical deblocking filter
+@table @option
+@item difference
+Difference factor where higher values mean more deblocking (default: @code{32}).
+@item flatness
+Flatness threshold where lower values mean more deblocking (default: @code{39}).
+@end table
+
+@item ha/hadeblock[:difference[:flatness]]
+Accurate horizontal deblocking filter
+@table @option
+@item difference
+Difference factor where higher values mean more deblocking (default: @code{32}).
+@item flatness
+Flatness threshold where lower values mean more deblocking (default: @code{39}).
+@end table
+
+@item va/vadeblock[:difference[:flatness]]
+Accurate vertical deblocking filter
+@table @option
+@item difference
+Difference factor where higher values mean more deblocking (default: @code{32}).
+@item flatness
+Flatness threshold where lower values mean more deblocking (default: @code{39}).
+@end table
+@end table
+
+The horizontal and vertical deblocking filters share the difference and
+flatness values so you cannot set different horizontal and vertical
+thresholds.
+
+@table @option
+@item h1/x1hdeblock
+Experimental horizontal deblocking filter
+
+@item v1/x1vdeblock
+Experimental vertical deblocking filter
+
+@item dr/dering
+Deringing filter
+
+@item tn/tmpnoise[:threshold1[:threshold2[:threshold3]]], temporal noise reducer
+@table @option
+@item threshold1
+larger -> stronger filtering
+@item threshold2
+larger -> stronger filtering
+@item threshold3
+larger -> stronger filtering
+@end table
+
+@item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
+@table @option
+@item f/fullyrange
+Stretch luminance to @code{0-255}.
+@end table
+
+@item lb/linblenddeint
+Linear blend deinterlacing filter that deinterlaces the given block by
+filtering all lines with a @code{(1 2 1)} filter.
+
+@item li/linipoldeint
+Linear interpolating deinterlacing filter that deinterlaces the given block by
+linearly interpolating every second line.
+
+@item ci/cubicipoldeint
+Cubic interpolating deinterlacing filter deinterlaces the given block by
+cubically interpolating every second line.
+
+@item md/mediandeint
+Median deinterlacing filter that deinterlaces the given block by applying a
+median filter to every second line.
+
+@item fd/ffmpegdeint
+FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
+second line with a @code{(-1 4 2 4 -1)} filter.
+
+@item l5/lowpass5
+Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
+block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
+
+@item fq/forceQuant[:quantizer]
+Overrides the quantizer table from the input with the constant quantizer you
+specify.
+@table @option
+@item quantizer
+Quantizer to use
+@end table
+
+@item de/default
+Default pp filter combination (@code{hb:a,vb:a,dr:a})
+
+@item fa/fast
+Fast pp filter combination (@code{h1:a,v1:a,dr:a})
+
+@item ac
+High quality pp filter combination (@code{ha:a:128:7,va:a,dr:a})
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Apply horizontal and vertical deblocking, deringing and automatic
+brightness/contrast:
+@example
+pp=hb/vb/dr/al
+@end example
+
+@item
+Apply default filters without brightness/contrast correction:
+@example
+pp=de/-al
+@end example
+
+@item
+Apply default filters and temporal denoiser:
+@example
+pp=default/tmpnoise:1:2:3
+@end example
+
+@item
+Apply deblocking on luminance only, and switch vertical deblocking on or off
+automatically depending on available CPU time:
+@example
+pp=hb:y/vb:a
+@end example
+@end itemize
+
+@section removelogo
+
+Suppress a TV station logo, using an image file to determine which
+pixels comprise the logo. It works by filling in the pixels that
+comprise the logo with neighboring pixels.
+
+This filter requires one argument which specifies the filter bitmap
+file, which can be any image format supported by libavformat. The
+width and height of the image file must match those of the video
+stream being processed.
+
+Pixels in the provided bitmap image with a value of zero are not
+considered part of the logo, non-zero pixels are considered part of
+the logo. If you use white (255) for the logo and black (0) for the
+rest, you will be safe. For making the filter bitmap, it is
+recommended to take a screen capture of a black frame with the logo
+visible, and then using a threshold filter followed by the erode
+filter once or twice.
+
+If needed, little splotches can be fixed manually. Remember that if
+logo pixels are not covered, the filter quality will be much
+reduced. Marking too many pixels as part of the logo does not hurt as
+much, but it will increase the amount of blurring needed to cover over
+the image and will destroy more information than necessary, and extra
+pixels will slow things down on a large logo.
+
+@section scale
+
+Scale (resize) the input video, using the libswscale library.
+
+The scale filter forces the output display aspect ratio to be the same
+of the input, by changing the output sample aspect ratio.
+
+This filter accepts a list of named options in the form of
+@var{key}=@var{value} pairs separated by ":". If the key for the first
+two options is not specified, the assumed keys for the first two
+values are @code{w} and @code{h}. If the first option has no key and
+can be interpreted like a video size specification, it will be used
+to set the video size.
+
+A description of the accepted options follows.
+
+@table @option
+@item width, w
+Set the video width expression, default value is @code{iw}. See below
+for the list of accepted constants.
+
+@item height, h
+Set the video heiht expression, default value is @code{ih}.
+See below for the list of accepted constants.
+
+@item interl
+Set the interlacing. It accepts the following values:
+
+@table @option
+@item 1
+force interlaced aware scaling
+
+@item 0
+do not apply interlaced scaling
+
+@item -1
+select interlaced aware scaling depending on whether the source frames
+are flagged as interlaced or not
+@end table
+
+Default value is @code{0}.
+
+@item flags
+Set libswscale scaling flags. If not explictly specified the filter
+applies a bilinear scaling algorithm.
+
+@item size, s
+Set the video size, the value must be a valid abbreviation or in the
+form @var{width}x@var{height}.
+@end table
+
+The values of the @var{w} and @var{h} options are expressions
+containing the following constants:
+
+@table @option
+@item in_w, in_h
+the input width and height
+
+@item iw, ih
+same as @var{in_w} and @var{in_h}
+
+@item out_w, out_h
+the output (cropped) width and height
+
+@item ow, oh
+same as @var{out_w} and @var{out_h}
+
+@item a
+same as @var{iw} / @var{ih}
+
+@item sar
+input sample aspect ratio
+
+@item dar
+input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
+
+@item hsub, vsub
+horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+@end table
+
+If the input image format is different from the format requested by
+the next filter, the scale filter will convert the input to the
+requested format.
+
+If the value for @var{width} or @var{height} is 0, the respective input
+size is used for the output.
+
+If the value for @var{width} or @var{height} is -1, the scale filter will
+use, for the respective output size, a value that maintains the aspect
+ratio of the input image.
+
+@subsection Examples
+
+@itemize
+@item
+Scale the input video to a size of 200x100:
+@example
+scale=200:100
+@end example
+
+This is equivalent to:
+@example
+scale=w=200:h=100
+@end example
+
+or:
+@example
+scale=200x100
+@end example
+
+@item
+Specify a size abbreviation for the output size:
+@example
+scale=qcif
+@end example
+
+which can also be written as:
+@example
+scale=size=qcif
+@end example
+
+@item
+Scale the input to 2x:
+@example
+scale=2*iw:2*ih
+@end example
+
+@item
+The above is the same as:
+@example
+scale=2*in_w:2*in_h
+@end example
+
+@item
+Scale the input to 2x with forced interlaced scaling:
+@example
+scale=2*iw:2*ih:interl=1
+@end example
+
+@item
+Scale the input to half size:
+@example
+scale=iw/2:ih/2
+@end example
+
+@item
+Increase the width, and set the height to the same size:
+@example
+scale=3/2*iw:ow
+@end example
+
+@item
+Seek for Greek harmony:
+@example
+scale=iw:1/PHI*iw
+scale=ih*PHI:ih
+@end example
+
+@item
+Increase the height, and set the width to 3/2 of the height:
+@example
+scale=3/2*oh:3/5*ih
+@end example
+
+@item
+Increase the size, but make the size a multiple of the chroma
+subsample values:
+@example
+scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
+@end example
+
+@item
+Increase the width to a maximum of 500 pixels, keep the same input
+aspect ratio:
+@example
+scale='min(500\, iw*3/2):-1'
+@end example
+@end itemize
+
+@section separatefields
+
+The @code{separatefields} takes a frame-based video input and splits
+each frame into its components fields, producing a new half height clip
+with twice the frame rate and twice the frame count.
+
+This filter use field-dominance information in frame to decide which
+of each pair of fields to place first in the output.
+If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
+
+@section setdar, setsar
+
+The @code{setdar} filter sets the Display Aspect Ratio for the filter
+output video.
+
+This is done by changing the specified Sample (aka Pixel) Aspect
+Ratio, according to the following equation:
+@example
+@var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
+@end example
+
+Keep in mind that the @code{setdar} filter does not modify the pixel
+dimensions of the video frame. Also the display aspect ratio set by
+this filter may be changed by later filters in the filterchain,
+e.g. in case of scaling or if another "setdar" or a "setsar" filter is
+applied.
+
+The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
+the filter output video.
+
+Note that as a consequence of the application of this filter, the
+output display aspect ratio will change according to the equation
+above.
+
+Keep in mind that the sample aspect ratio set by the @code{setsar}
+filter may be changed by later filters in the filterchain, e.g. if
+another "setsar" or a "setdar" filter is applied.
+
+The @code{setdar} and @code{setsar} filters accept a string in the
+form @var{num}:@var{den} expressing an aspect ratio, or the following
+named options, expressed as a sequence of @var{key}=@var{value} pairs,
+separated by ":".
+
+@table @option
+@item max
+Set the maximum integer value to use for expressing numerator and
+denominator when reducing the expressed aspect ratio to a rational.
+Default value is @code{100}.
+
- @item r, ratio:
++@item r, ratio, dar, sar:
+Set the aspect ratio used by the filter.
+
+The parameter can be a floating point number string, an expression, or
+a string of the form @var{num}:@var{den}, where @var{num} and
+@var{den} are the numerator and denominator of the aspect ratio. If
+the parameter is not specified, it is assumed the value "0".
+In case the form "@var{num}:@var{den}" the @code{:} character should
+be escaped.
+@end table
+
+If the keys are omitted in the named options list, the specifed values
+are assumed to be @var{ratio} and @var{max} in that order.
+
+For example to change the display aspect ratio to 16:9, specify:
+@example
+setdar='16:9'
- @end example
-
- The example above is equivalent to:
- @example
++# the above is equivalent to
+setdar=1.77777
++setdar=dar=16/9
++setdar=dar=1.77777
+@end example
+
+To change the sample aspect ratio to 10:11, specify:
+@example
+setsar='10:11'
++# the above is equivalent to
++setsar='sar=10/11'
+@end example
+
+To set a display aspect ratio of 16:9, and specify a maximum integer value of
+1000 in the aspect ratio reduction, use the command:
+@example
+setdar=ratio='16:9':max=1000
+@end example
+
+@anchor{setfield}
+@section setfield
+
+Force field for the output video frame.
+
+The @code{setfield} filter marks the interlace type field for the
+output frames. It does not change the input frame, but only sets the
+corresponding property, which affects how the frame is treated by
+following filters (e.g. @code{fieldorder} or @code{yadif}).
-The flags map the corresponding flags supported by libfreetype, and are
-a combination of the following values:
-@table @var
-@item default
-@item no_scale
-@item no_hinting
-@item render
-@item no_bitmap
-@item vertical_layout
-@item force_autohint
-@item crop_bitmap
-@item pedantic
-@item ignore_global_advance_width
-@item no_recurse
-@item ignore_transform
-@item monochrome
-@item linear_design
-@item no_autohint
-@item end table
+This filter accepts a single option @option{mode}, which can be
+specified either by setting @code{mode=VALUE} or setting the value
+alone. Available values are:
+
+@table @samp
+@item auto
+Keep the same field property.
+
+@item bff
+Mark the frame as bottom-field-first.
+
+@item tff
+Mark the frame as top-field-first.
+
+@item prog
+Mark the frame as progressive.
@end table
-Default value is "render".
+@section showinfo
-For more information consult the documentation for the FT_LOAD_*
-libfreetype flags.
+Show a line containing various information for each input video frame.
+The input video is not modified.
-@item tabsize
-The size in number of spaces to use for rendering the tab.
-Default value is 4.
+The shown line contains a sequence of key/value pairs of the form
+@var{key}:@var{value}.
-@item fix_bounds
-If true, check and fix text coords to avoid clipping.
+A description of each shown parameter follows:
+
+@table @option
+@item n
+sequential number of the input frame, starting from 0
+
+@item pts
+Presentation TimeStamp of the input frame, expressed as a number of
+time base units. The time base unit depends on the filter input pad.
+
+@item pts_time
+Presentation TimeStamp of the input frame, expressed as a number of
+seconds
+
+@item pos
+position of the frame in the input stream, -1 if this information in
+unavailable and/or meaningless (for example in case of synthetic video)
+
+@item fmt
+pixel format name
+
+@item sar
+sample aspect ratio of the input frame, expressed in the form
+@var{num}/@var{den}
+
+@item s
+size of the input frame, expressed in the form
+@var{width}x@var{height}
+
+@item i
+interlaced mode ("P" for "progressive", "T" for top field first, "B"
+for bottom field first)
+
+@item iskey
+1 if the frame is a key frame, 0 otherwise
+
+@item type
+picture type of the input frame ("I" for an I-frame, "P" for a
+P-frame, "B" for a B-frame, "?" for unknown type).
+Check also the documentation of the @code{AVPictureType} enum and of
+the @code{av_get_picture_type_char} function defined in
+@file{libavutil/avutil.h}.
+
+@item checksum
+Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
+
+@item plane_checksum
+Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
+expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
+@end table
+
+@section smartblur
+
+Blur the input video without impacting the outlines.
+
+This filter accepts parameters as a list of @var{key}=@var{value} pairs,
+separated by ":".
+
+If the key of the first options is omitted, the arguments are
+interpreted according to the syntax:
+@var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
+
+A description of the accepted options follows.
+
+@table @option
+@item luma_radius, lr
+@item chroma_radius, cr
+Set the luma/chroma radius. The option value must be a float number in
+the range [0.1,5.0] that specifies the variance of the gaussian filter
+used to blur the image (slower if larger). Default value is 1.0.
+
+@item luma_strength, ls
+@item chroma_strength, cs
+Set the luma/chroma strength. The option value must be a float number
+in the range [-1.0,1.0] that configures the blurring. A value included
+in [0.0,1.0] will blur the image whereas a value included in
+[-1.0,0.0] will sharpen the image. Default value is 1.0.
+
+@item luma_threshold, lt
+@item chroma_threshold, ct
+Set the luma/chroma threshold used as a coefficient to determine
+whether a pixel should be blurred or not. The option value must be an
+integer in the range [-30,30]. A value of 0 will filter all the image,
+a value included in [0,30] will filter flat areas and a value included
+in [-30,0] will filter edges. Default value is 0.
+@end table
+
+If a chroma option is not explicitly set, the corresponding luma value
+is set.
+
+@section stereo3d
+
+Convert between different stereoscopic image formats.
+
+This filter accepts the following named options, expressed as a
+sequence of @var{key}=@var{value} pairs, separated by ":".
+
+@table @option
+@item in
+Set stereoscopic image format of input.
+
+Available values for input image formats are:
+@table @samp
+@item sbsl
+side by side parallel (left eye left, right eye right)
+
+@item sbsr
+side by side crosseye (right eye left, left eye right)
+
+@item sbs2l
+side by side parallel with half width resolution
+(left eye left, right eye right)
+
+@item sbs2r
+side by side crosseye with half width resolution
+(right eye left, left eye right)
+
+@item abl
+above-below (left eye above, right eye below)
+
+@item abr
+above-below (right eye above, left eye below)
+
+@item ab2l
+above-below with half height resolution
+(left eye above, right eye below)
+
+@item ab2r
+above-below with half height resolution
+(right eye above, left eye below)
+
+Default value is @samp{sbsl}.
+@end table
+
+@item out
+Set stereoscopic image format of output.
+
+Available values for output image formats are all the input formats as well as:
+@table @samp
+@item arbg
+anaglyph red/blue gray
+(red filter on left eye, blue filter on right eye)
+
+@item argg
+anaglyph red/green gray
+(red filter on left eye, green filter on right eye)
+
+@item arcg
+anaglyph red/cyan gray
+(red filter on left eye, cyan filter on right eye)
+
+@item arch
+anaglyph red/cyan half colored
+(red filter on left eye, cyan filter on right eye)
+
+@item arcc
+anaglyph red/cyan color
+(red filter on left eye, cyan filter on right eye)
+
+@item arcd
+anaglyph red/cyan color optimized with the least squares projection of dubois
+(red filter on left eye, cyan filter on right eye)
+
+@item agmg
+anaglyph green/magenta gray
+(green filter on left eye, magenta filter on right eye)
+
+@item agmh
+anaglyph green/magenta half colored
+(green filter on left eye, magenta filter on right eye)
+
+@item agmc
+anaglyph green/magenta colored
+(green filter on left eye, magenta filter on right eye)
+
+@item agmd
+anaglyph green/magenta color optimized with the least squares projection of dubois
+(green filter on left eye, magenta filter on right eye)
+
+@item aybg
+anaglyph yellow/blue gray
+(yellow filter on left eye, blue filter on right eye)
+
+@item aybh
+anaglyph yellow/blue half colored
+(yellow filter on left eye, blue filter on right eye)
+
+@item aybc
+anaglyph yellow/blue colored
+(yellow filter on left eye, blue filter on right eye)
+
+@item aybd
+anaglyph yellow/blue color optimized with the least squares projection of dubois
+(yellow filter on left eye, blue filter on right eye)
+
+@item irl
+interleaved rows (left eye has top row, right eye starts on next row)
+
+@item irr
+interleaved rows (right eye has top row, left eye starts on next row)
+
+@item ml
+mono output (left eye only)
+
+@item mr
+mono output (right eye only)
+@end table
+
+Default value is @samp{arcd}.
+@end table
+
+@anchor{subtitles}
+@section subtitles
+
+Draw subtitles on top of input video using the libass library.
+
+To enable compilation of this filter you need to configure FFmpeg with
+@code{--enable-libass}. This filter also requires a build with libavcodec and
+libavformat to convert the passed subtitles file to ASS (Advanced Substation
+Alpha) subtitles format.
+
+This filter accepts the following named options, expressed as a
+sequence of @var{key}=@var{value} pairs, separated by ":".
+
+@table @option
+@item filename, f
+Set the filename of the subtitle file to read. It must be specified.
+
+@item original_size
+Specify the size of the original video, the video for which the ASS file
+was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
+necessary to correctly scale the fonts if the aspect ratio has been changed.
+
+@item charenc
+Set subtitles input character encoding. @code{subtitles} filter only. Only
+useful if not UTF-8.
@end table
-For example the command:
+If the first key is not specified, it is assumed that the first value
+specifies the @option{filename}.
+
+For example, to render the file @file{sub.srt} on top of the input
+video, use the command:
@example
-drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
+subtitles=sub.srt
+@end example
+
+which is equivalent to:
+@example
+subtitles=filename=sub.srt
@end example
-will draw "Test Text" with font FreeSerif, using the default values
-for the optional parameters.
+@section split
+
+Split input video into several identical outputs.
+
+The filter accepts a single parameter which specifies the number of outputs. If
+unspecified, it defaults to 2.
-The command:
+For example
@example
-drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
- x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
+ffmpeg -i INPUT -filter_complex split=5 OUTPUT
@end example
+will create 5 copies of the input video.
-will draw 'Test Text' with font FreeSerif of size 24 at position x=100
-and y=50 (counting from the top-left corner of the screen), text is
-yellow with a red box around it. Both the text and the box have an
-opacity of 20%.
+For example:
+@example
+[in] split [splitout1][splitout2];
+[splitout1] crop=100:100:0:0 [cropout];
+[splitout2] pad=200:200:100:100 [padout];
+@end example
-Note that the double quotes are not necessary if spaces are not used
-within the parameter list.
+will create two separate outputs from the same input, one cropped and
+one padded.
-For more information about libfreetype, check:
-@url{http://www.freetype.org/}.
+@section super2xsai
-@section fade
+Scale the input by 2x and smooth using the Super2xSaI (Scale and
+Interpolate) pixel art scaling algorithm.
-Apply fade-in/out effect to input video.
+Useful for enlarging pixel art images without reducing sharpness.
+
+@section swapuv
+Swap U & V plane.
+
+@section thumbnail
+Select the most representative frame in a given sequence of consecutive frames.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+thumbnail[=@var{n}].
+
+@table @option
+@item n
+Set the frames batch size to analyze; in a set of @var{n} frames, the filter
+will pick one of them, and then handle the next batch of @var{n} frames until
+the end. Default is @code{100}.
+@end table
+
+Since the filter keeps track of the whole frames sequence, a bigger @var{n}
+value will result in a higher memory usage, so a high value is not recommended.
+
+@subsection Examples
+
+@itemize
+@item
+Extract one picture each 50 frames:
+@example
+thumbnail=50
+@end example
+
+@item
+Complete example of a thumbnail creation with @command{ffmpeg}:
+@example
+ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
+@end example
+@end itemize
+
+@section tile
+
+Tile several successive frames together.
+
+It accepts a list of options in the form of @var{key}=@var{value} pairs
+separated by ":". A description of the accepted options follows.
+
+@table @option
+
+@item layout
+Set the grid size (i.e. the number of lines and columns) in the form
+"@var{w}x@var{h}".
+
+@item margin
+Set the outer border margin in pixels.
+
+@item padding
+Set the inner border thickness (i.e. the number of pixels between frames). For
+more advanced padding options (such as having different values for the edges),
+refer to the pad video filter.
+
+@item nb_frames
+Set the maximum number of frames to render in the given area. It must be less
+than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
+the area will be used.
+
+@end table
+
+Alternatively, the options can be specified as a flat string:
+
+@var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
+
+For example, produce 8x8 PNG tiles of all keyframes (@option{-skip_frame
+nokey}) in a movie:
+@example
+ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
+@end example
+The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
+duplicating each output frame to accomodate the originally detected frame
+rate.
+
+Another example to display @code{5} pictures in an area of @code{3x2} frames,
+with @code{7} pixels between them, and @code{2} pixels of initial margin, using
+mixed flat and named options:
+@example
+tile=3x2:nb_frames=5:padding=7:margin=2
+@end example
+
+@section tinterlace
+
+Perform various types of temporal field interlacing.
+
+Frames are counted starting from 1, so the first input frame is
+considered odd.
+
+This filter accepts options in the form of @var{key}=@var{value} pairs
+separated by ":".
+Alternatively, the @var{mode} option can be specified as a value alone,
+optionally followed by a ":" and further ":" separated @var{key}=@var{value}
+pairs.
+
+A description of the accepted options follows.
+
+@table @option
+
+@item mode
+Specify the mode of the interlacing. This option can also be specified
+as a value alone. See below for a list of values for this option.
+
+Available values are:
+
+@table @samp
+@item merge, 0
+Move odd frames into the upper field, even into the lower field,
+generating a double height frame at half frame rate.
+
+@item drop_odd, 1
+Only output even frames, odd frames are dropped, generating a frame with
+unchanged height at half frame rate.
+
+@item drop_even, 2
+Only output odd frames, even frames are dropped, generating a frame with
+unchanged height at half frame rate.
+
+@item pad, 3
+Expand each frame to full height, but pad alternate lines with black,
+generating a frame with double height at the same input frame rate.
+
+@item interleave_top, 4
+Interleave the upper field from odd frames with the lower field from
+even frames, generating a frame with unchanged height at half frame rate.
+
+@item interleave_bottom, 5
+Interleave the lower field from odd frames with the upper field from
+even frames, generating a frame with unchanged height at half frame rate.
+
+@item interlacex2, 6
+Double frame rate with unchanged height. Frames are inserted each
+containing the second temporal field from the previous input frame and
+the first temporal field from the next input frame. This mode relies on
+the top_field_first flag. Useful for interlaced video displays with no
+field synchronisation.
+@end table
+
+Numeric values are deprecated but are accepted for backward
+compatibility reasons.
+
+Default mode is @code{merge}.
+
+@item flags
+Specify flags influencing the filter process.
+
+Available value for @var{flags} is:
+
+@table @option
+@item low_pass_filter, vlfp
+Enable vertical low-pass filtering in the filter.
+Vertical low-pass filtering is required when creating an interlaced
+destination from a progressive source which contains high-frequency
+vertical detail. Filtering will reduce interlace 'twitter' and Moire
+patterning.
+
+Vertical low-pass filtering can only be enabled for @option{mode}
+@var{interleave_top} and @var{interleave_bottom}.
+
+@end table
+@end table
+
+@section transpose
+
+Transpose rows with columns in the input video and optionally flip it.
+
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ':'. If the key of the first options is omitted,
+the arguments are interpreted according to the syntax
+@var{dir}:@var{passthrough}.
+
+@table @option
+@item dir
+Specify the transposition direction. Can assume the following values:
+
+@table @samp
+@item 0, 4
+Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
+@example
+L.R L.l
+. . -> . .
+l.r R.r
+@end example
+
+@item 1, 5
+Rotate by 90 degrees clockwise, that is:
+@example
+L.R l.L
+. . -> . .
+l.r r.R
+@end example
+
+@item 2, 6
+Rotate by 90 degrees counterclockwise, that is:
+@example
+L.R R.r
+. . -> . .
+l.r L.l
+@end example
-It accepts the parameters:
-@var{type}:@var{start_frame}:@var{nb_frames}
+@item 3, 7
+Rotate by 90 degrees clockwise and vertically flip, that is:
+@example
+L.R r.R
+. . -> . .
+l.r l.L
+@end example
+@end table
-@var{type} specifies if the effect type, can be either "in" for
-fade-in, or "out" for a fade-out effect.
+For values between 4-7, the transposition is only done if the input
+video geometry is portrait and not landscape. These values are
+deprecated, the @code{passthrough} option should be used instead.
-@var{start_frame} specifies the number of the start frame for starting
-to apply the fade effect.
+@item passthrough
+Do not apply the transposition if the input geometry matches the one
+specified by the specified value. It accepts the following values:
+@table @samp
+@item none
+Always apply transposition.
+@item portrait
+Preserve portrait geometry (when @var{height} >= @var{width}).
+@item landscape
+Preserve landscape geometry (when @var{width} >= @var{height}).
+@end table
-@var{nb_frames} specifies the number of frames for which the fade
-effect has to last. At the end of the fade-in effect the output video
-will have the same intensity as the input video, at the end of the
-fade-out transition the output video will be completely black.
+Default value is @code{none}.
+@end table
-A few usage examples follow, usable too as test scenarios.
+For example to rotate by 90 degrees clockwise and preserve portrait
+layout:
@example
-# fade in first 30 frames of video
-fade=in:0:30
+transpose=dir=1:passthrough=portrait
+@end example
-# fade out last 45 frames of a 200-frame video
-fade=out:155:45
+The command above can also be specified as:
+@example
+transpose=1:portrait
+@end example
-# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
-fade=in:0:25, fade=out:975:25
+@section unsharp
-# make first 5 frames black, then fade in from frame 5-24
-fade=in:5:20
-@end example
+Sharpen or blur the input video.
-@section fieldorder
+This filter accepts parameters as a list of @var{key}=@var{value} pairs,
+separated by ":".
-Transform the field order of the input video.
+If the key of the first options is omitted, the arguments are
+interpreted according to the syntax:
+@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
-It accepts one parameter which specifies the required field order that
-the input interlaced video will be transformed to. The parameter can
-assume one of the following values:
+A description of the accepted options follows.
@table @option
-@item 0 or bff
-output bottom field first
-@item 1 or tff
-output top field first
+@item luma_msize_x, lx
+@item chroma_msize_x, cx
+Set the luma/chroma matrix horizontal size. It must be an odd integer
+between 3 and 63, default value is 5.
+
+@item luma_msize_y, ly
+@item chroma_msize_y, cy
+Set the luma/chroma matrix vertical size. It must be an odd integer
+between 3 and 63, default value is 5.
+
+@item luma_amount, la
+@item chroma_amount, ca
+Set the luma/chroma effect strength. It can be a float number,
+reasonable values lay between -1.5 and 1.5.
+
+Negative values will blur the input video, while positive values will
+sharpen it, a value of zero will disable the effect.
+
+Default value is 1.0 for @option{luma_amount}, 0.0 for
+@option{chroma_amount}.
@end table
-Default value is "tff".
-
-Transformation is achieved by shifting the picture content up or down
-by one line, and filling the remaining line with appropriate picture content.
-This method is consistent with most broadcast field order converters.
-
-If the input video is not flagged as being interlaced, or it is already
-flagged as being of the required output field order then this filter does
-not alter the incoming video.
+@subsection Examples
-This filter is very useful when converting to or from PAL DV material,
-which is bottom field first.
+@itemize
+@item
+Apply strong luma sharpen effect:
+@example
+unsharp=7:7:2.5
+@end example
-For example:
+@item
+Apply strong blur of both luma and chroma parameters:
@example
-./avconv -i in.vob -vf "fieldorder=bff" out.dv
+unsharp=7:7:-2:7:7:-2
@end example
+@end itemize
-@section fifo
+@section vflip
-Buffer input images and send them when they are requested.
+Flip the input video vertically.
-This filter is mainly useful when auto-inserted by the libavfilter
-framework.
+@example
+ffmpeg -i in.avi -vf "vflip" out.avi
+@end example
-The filter does not take parameters.
+@section yadif
-@section format
+Deinterlace the input video ("yadif" means "yet another deinterlacing
+filter").
-Convert the input video to one of the specified pixel formats.
-Libavfilter will try to pick one that is supported for the input to
-the next filter.
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":". If the key of the first options is omitted,
+the arguments are interpreted according to syntax
+@var{mode}:@var{parity}:@var{deint}.
-This filter accepts the following parameters:
-@table @option
+The description of the accepted parameters follows.
-@item pix_fmts
-A '|'-separated list of pixel format names, for example
-"pix_fmts=yuv420p|monow|rgb24".
+@table @option
+@item mode
+Specify the interlacing mode to adopt. Accept one of the following
+values:
+@table @option
+@item 0, send_frame
+output 1 frame for each frame
+@item 1, send_field
+output 1 frame for each field
+@item 2, send_frame_nospatial
+like @code{send_frame} but skip spatial interlacing check
+@item 3, send_field_nospatial
+like @code{send_field} but skip spatial interlacing check
@end table
-Some examples follow:
-@example
-# convert the input video to the format "yuv420p"
-format=pix_fmts=yuv420p
-
-# convert the input video to any of the formats in the list
-format=pix_fmts=yuv420p|yuv444p|yuv410p
-@end example
-
-@section fps
+Default value is @code{send_frame}.
-Convert the video to specified constant framerate by duplicating or dropping
-frames as necessary.
+@item parity
+Specify the picture field parity assumed for the input interlaced
+video. Accept one of the following values:
-This filter accepts the following named parameters:
@table @option
-
-@item fps
-Desired output framerate.
-
+@item 0, tff
+assume top field first
+@item 1, bff
+assume bottom field first
+@item -1, auto
+enable automatic detection
@end table
-@anchor{frei0r}
-@section frei0r
+Default value is @code{auto}.
+If interlacing is unknown or decoder does not export this information,
+top field first will be assumed.
-Apply a frei0r effect to the input video.
+@item deint
+Specify which frames to deinterlace. Accept one of the following
+values:
-To enable compilation of this filter you need to install the frei0r
-header and configure Libav with --enable-frei0r.
+@table @option
+@item 0, all
+deinterlace all frames
+@item 1, interlaced
+only deinterlace frames marked as interlaced
+@end table
-The filter supports the syntax:
-@example
-@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
-@end example
+Default value is @code{all}.
+@end table
-@var{filter_name} is the name to the frei0r effect to load. If the
-environment variable @env{FREI0R_PATH} is defined, the frei0r effect
-is searched in each one of the directories specified by the colon
-separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
-paths, which are in this order: @file{HOME/.frei0r-1/lib/},
-@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
+@c man end VIDEO FILTERS
-@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
-for the frei0r effect.
+@chapter Video Sources
+@c man begin VIDEO SOURCES
-A frei0r effect parameter can be a boolean (whose values are specified
-with "y" and "n"), a double, a color (specified by the syntax
-@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
-numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
-description), a position (specified by the syntax @var{X}/@var{Y},
-@var{X} and @var{Y} being float numbers) and a string.
+Below is a description of the currently available video sources.
-The number and kind of parameters depend on the loaded effect. If an
-effect parameter is not specified the default value is set.
+@section buffer
-Some examples follow:
-@example
-# apply the distort0r effect, set the first two double parameters
-frei0r=distort0r:0.5:0.01
+Buffer video frames, and make them available to the filter chain.
-# apply the colordistance effect, takes a color as first parameter
-frei0r=colordistance:0.2/0.3/0.4
-frei0r=colordistance:violet
-frei0r=colordistance:0x112233
+This source is mainly intended for a programmatic use, in particular
+through the interface defined in @file{libavfilter/vsrc_buffer.h}.
-# apply the perspective effect, specify the top left and top right
-# image positions
-frei0r=perspective:0.2/0.2:0.8/0.2
-@end example
+It accepts a list of options in the form of @var{key}=@var{value} pairs
+separated by ":". A description of the accepted options follows.
-For more information see:
-@url{http://piksel.org/frei0r}
+@table @option
-@section gradfun
+@item video_size
+Specify the size (width and height) of the buffered video frames.
-Fix the banding artifacts that are sometimes introduced into nearly flat
-regions by truncation to 8bit colordepth.
-Interpolate the gradients that should go where the bands are, and
-dither them.
+@item pix_fmt
+A string representing the pixel format of the buffered video frames.
+It may be a number corresponding to a pixel format, or a pixel format
+name.
-This filter is designed for playback only. Do not use it prior to
-lossy compression, because compression tends to lose the dither and
-bring back the bands.
+@item time_base
+Specify the timebase assumed by the timestamps of the buffered frames.
-The filter takes two optional parameters, separated by ':':
-@var{strength}:@var{radius}
+@item time_base
+Specify the frame rate expected for the video stream.
-@var{strength} is the maximum amount by which the filter will change
-any one pixel. Also the threshold for detecting nearly flat
-regions. Acceptable values range from .51 to 64, default value is
-1.2, out-of-range values will be clipped to the valid range.
+@item pixel_aspect
+Specify the sample aspect ratio assumed by the video frames.
-@var{radius} is the neighborhood to fit the gradient to. A larger
-radius makes for smoother gradients, but also prevents the filter from
-modifying the pixels near detailed regions. Acceptable values are
-8-32, default value is 16, out-of-range values will be clipped to the
-valid range.
+@item sws_param
+Specify the optional parameters to be used for the scale filter which
+is automatically inserted when an input change is detected in the
+input size or format.
+@end table
+For example:
@example
-# default parameters
-gradfun=1.2:16
-
-# omitting radius
-gradfun=1.2
+buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
@end example
-@section hflip
-
-Flip the input video horizontally.
-
-For example to horizontally flip the input video with @command{avconv}:
+will instruct the source to accept video frames with size 320x240 and
+with format "yuv410p", assuming 1/24 as the timestamps timebase and
+square pixels (1:1 sample aspect ratio).
+Since the pixel format with name "yuv410p" corresponds to the number 6
+(check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
+this example corresponds to:
@example
-avconv -i in.avi -vf "hflip" out.avi
+buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
@end example
-@section hqdn3d
-
-High precision/quality 3d denoise filter. This filter aims to reduce
-image noise producing smooth images and making still images really
-still. It should enhance compressibility.
-
-It accepts the following optional parameters:
-@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
-
-@table @option
-@item luma_spatial
-a non-negative float number which specifies spatial luma strength,
-defaults to 4.0
-
-@item chroma_spatial
-a non-negative float number which specifies spatial chroma strength,
-defaults to 3.0*@var{luma_spatial}/4.0
+Alternatively, the options can be specified as a flat string, but this
+syntax is deprecated:
-@item luma_tmp
-a float number which specifies luma temporal strength, defaults to
-6.0*@var{luma_spatial}/4.0
+@var{width}:@var{height}:@var{pix_fmt}:@var{time_base.num}:@var{time_base.den}:@var{pixel_aspect.num}:@var{pixel_aspect.den}[:@var{sws_param}]
-@item chroma_tmp
-a float number which specifies chroma temporal strength, defaults to
-@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
-@end table
+@section cellauto
-@section lut, lutrgb, lutyuv
+Create a pattern generated by an elementary cellular automaton.
-Compute a look-up table for binding each pixel component input value
-to an output value, and apply it to input video.
+The initial state of the cellular automaton can be defined through the
+@option{filename}, and @option{pattern} options. If such options are
+not specified an initial state is created randomly.
-@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
-to an RGB input video.
+At each new frame a new row in the video is filled with the result of
+the cellular automaton next generation. The behavior when the whole
+frame is filled is defined by the @option{scroll} option.
-These filters accept in input a ":"-separated list of options, which
-specify the expressions used for computing the lookup table for the
-corresponding pixel component values.
+This source accepts a list of options in the form of
+@var{key}=@var{value} pairs separated by ":". A description of the
+accepted options follows.
-The @var{lut} filter requires either YUV or RGB pixel formats in
-input, and accepts the options:
@table @option
-@item @var{c0} (first pixel component)
-@item @var{c1} (second pixel component)
-@item @var{c2} (third pixel component)
-@item @var{c3} (fourth pixel component, corresponds to the alpha component)
-@end table
+@item filename, f
+Read the initial cellular automaton state, i.e. the starting row, from
+the specified file.
+In the file, each non-whitespace character is considered an alive
+cell, a newline will terminate the row, and further characters in the
+file will be ignored.
-The exact component associated to each option depends on the format in
-input.
+@item pattern, p
+Read the initial cellular automaton state, i.e. the starting row, from
+the specified string.
-The @var{lutrgb} filter requires RGB pixel formats in input, and
-accepts the options:
-@table @option
-@item @var{r} (red component)
-@item @var{g} (green component)
-@item @var{b} (blue component)
-@item @var{a} (alpha component)
-@end table
+Each non-whitespace character in the string is considered an alive
+cell, a newline will terminate the row, and further characters in the
+string will be ignored.
-The @var{lutyuv} filter requires YUV pixel formats in input, and
-accepts the options:
-@table @option
-@item @var{y} (Y/luminance component)
-@item @var{u} (U/Cb component)
-@item @var{v} (V/Cr component)
-@item @var{a} (alpha component)
-@end table
+@item rate, r
+Set the video rate, that is the number of frames generated per second.
+Default is 25.
-The expressions can contain the following constants and functions:
+@item random_fill_ratio, ratio
+Set the random fill ratio for the initial cellular automaton row. It
+is a floating point number value ranging from 0 to 1, defaults to
+1/PHI.
-@table @option
-@item E, PI, PHI
-the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), PHI (golden ratio)
+This option is ignored when a file or a pattern is specified.
-@item w, h
-the input width and height
+@item random_seed, seed
+Set the seed for filling randomly the initial row, must be an integer
+included between 0 and UINT32_MAX. If not specified, or if explicitly
+set to -1, the filter will try to use a good random seed on a best
+effort basis.
-@item val
-input value for the pixel component
+@item rule
+Set the cellular automaton rule, it is a number ranging from 0 to 255.
+Default value is 110.
-@item clipval
-the input value clipped in the @var{minval}-@var{maxval} range
+@item size, s
+Set the size of the output video.
-@item maxval
-maximum value for the pixel component
+If @option{filename} or @option{pattern} is specified, the size is set
+by default to the width of the specified initial state row, and the
+height is set to @var{width} * PHI.
-@item minval
-minimum value for the pixel component
+If @option{size} is set, it must contain the width of the specified
+pattern string, and the specified pattern will be centered in the
+larger row.
-@item negval
-the negated value for the pixel component value clipped in the
-@var{minval}-@var{maxval} range , it corresponds to the expression
-"maxval-clipval+minval"
+If a filename or a pattern string is not specified, the size value
+defaults to "320x518" (used for a randomly generated initial state).
-@item clip(val)
-the computed value in @var{val} clipped in the
-@var{minval}-@var{maxval} range
+@item scroll
+If set to 1, scroll the output upward when all the rows in the output
+have been already filled. If set to 0, the new generated row will be
+written over the top row just after the bottom row is filled.
+Defaults to 1.
-@item gammaval(gamma)
-the computed gamma correction value of the pixel component value
-clipped in the @var{minval}-@var{maxval} range, corresponds to the
-expression
-"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
+@item start_full, full
+If set to 1, completely fill the output with generated rows before
+outputting the first frame.
+This is the default behavior, for disabling set the value to 0.
+@item stitch
+If set to 1, stitch the left and right row edges together.
+This is the default behavior, for disabling set the value to 0.
@end table
-All expressions default to "val".
+@subsection Examples
-Some examples follow:
+@itemize
+@item
+Read the initial state from @file{pattern}, and specify an output of
+size 200x400.
@example
-# negate input video
-lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
-lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
-
-# the above is the same as
-lutrgb="r=negval:g=negval:b=negval"
-lutyuv="y=negval:u=negval:v=negval"
-
-# negate luminance
-lutyuv=negval
-
-# remove chroma components, turns the video into a graytone image
-lutyuv="u=128:v=128"
-
-# apply a luma burning effect
-lutyuv="y=2*val"
+cellauto=f=pattern:s=200x400
+@end example
-# remove green and blue components
-lutrgb="g=0:b=0"
+@item
+Generate a random initial row with a width of 200 cells, with a fill
+ratio of 2/3:
+@example
+cellauto=ratio=2/3:s=200x200
+@end example
-# set a constant alpha channel value on input
-format=rgba,lutrgb=a="maxval-minval/2"
+@item
+Create a pattern generated by rule 18 starting by a single alive cell
+centered on an initial row with width 100:
+@example
+cellauto=p=@@:s=100x400:full=0:rule=18
+@end example
-# correct luminance gamma by a 0.5 factor
-lutyuv=y=gammaval(0.5)
+@item
+Specify a more elaborated initial pattern:
+@example
+cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
@end example
-@section negate
-
-Negate input video.
+@end itemize
-This filter accepts an integer in input, if non-zero it negates the
-alpha component (if available). The default value in input is 0.
+@section mandelbrot
-@section noformat
+Generate a Mandelbrot set fractal, and progressively zoom towards the
+point specified with @var{start_x} and @var{start_y}.
-Force libavfilter not to use any of the specified pixel formats for the
-input to the next filter.
+This source accepts a list of options in the form of
+@var{key}=@var{value} pairs separated by ":". A description of the
+accepted options follows.
-This filter accepts the following parameters:
@table @option
-@item pix_fmts
-A '|'-separated list of pixel format names, for example
-"pix_fmts=yuv420p|monow|rgb24".
+@item end_pts
+Set the terminal pts value. Default value is 400.
-@end table
+@item end_scale
+Set the terminal scale value.
+Must be a floating point value. Default value is 0.3.
-Some examples follow:
-@example
-# force libavfilter to use a format different from "yuv420p" for the
-# input to the vflip filter
-noformat=pix_fmts=yuv420p,vflip
+@item inner
+Set the inner coloring mode, that is the algorithm used to draw the
+Mandelbrot fractal internal region.
-# convert the input video to any of the formats not contained in the list
-noformat=yuv420p|yuv444p|yuv410p
-@end example
+It shall assume one of the following values:
+@table @option
+@item black
+Set black mode.
+@item convergence
+Show time until convergence.
+@item mincol
+Set color based on point closest to the origin of the iterations.
+@item period
+Set period mode.
+@end table
-@section null
+Default value is @var{mincol}.
-Pass the video source unchanged to the output.
+@item bailout
+Set the bailout value. Default value is 10.0.
-@section ocv
+@item maxiter
+Set the maximum of iterations performed by the rendering
+algorithm. Default value is 7189.
-Apply video transform using libopencv.
+@item outer
+Set outer coloring mode.
+It shall assume one of following values:
+@table @option
+@item iteration_count
+Set iteration cound mode.
+@item normalized_iteration_count
+set normalized iteration count mode.
+@end table
+Default value is @var{normalized_iteration_count}.
-To enable this filter install libopencv library and headers and
-configure Libav with --enable-libopencv.
+@item rate, r
+Set frame rate, expressed as number of frames per second. Default
+value is "25".
-The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
+@item size, s
+Set frame size. Default value is "640x480".
-@var{filter_name} is the name of the libopencv filter to apply.
+@item start_scale
+Set the initial scale value. Default value is 3.0.
-@var{filter_params} specifies the parameters to pass to the libopencv
-filter. If not specified the default values are assumed.
+@item start_x
+Set the initial x position. Must be a floating point value between
+-100 and 100. Default value is -0.743643887037158704752191506114774.
-Refer to the official libopencv documentation for more precise
-information:
-@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
+@item start_y
+Set the initial y position. Must be a floating point value between
+-100 and 100. Default value is -0.131825904205311970493132056385139.
+@end table
-Follows the list of supported libopencv filters.
+@section mptestsrc
-@anchor{dilate}
-@subsection dilate
+Generate various test patterns, as generated by the MPlayer test filter.
-Dilate an image by using a specific structuring element.
-This filter corresponds to the libopencv function @code{cvDilate}.
+The size of the generated video is fixed, and is 256x256.
+This source is useful in particular for testing encoding features.
-It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
+This source accepts an optional sequence of @var{key}=@var{value} pairs,
+separated by ":". The description of the accepted options follows.
-@var{struct_el} represents a structuring element, and has the syntax:
-@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
+@table @option
-@var{cols} and @var{rows} represent the number of columns and rows of
-the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
-point, and @var{shape} the shape for the structuring element, and
-can be one of the values "rect", "cross", "ellipse", "custom".
+@item rate, r
+Specify the frame rate of the sourced video, as the number of frames
+generated per second. It has to be a string in the format
+@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
+number or a valid video frame rate abbreviation. The default value is
+"25".
-If the value for @var{shape} is "custom", it must be followed by a
-string of the form "=@var{filename}". The file with name
-@var{filename} is assumed to represent a binary image, with each
-printable character corresponding to a bright pixel. When a custom
-@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
-or columns and rows of the read file are assumed instead.
+@item duration, d
+Set the video duration of the sourced video. The accepted syntax is:
+@example
+[-]HH:MM:SS[.m...]
+[-]S+[.m...]
+@end example
+See also the function @code{av_parse_time()}.
-The default value for @var{struct_el} is "3x3+0x0/rect".
+If not specified, or the expressed duration is negative, the video is
+supposed to be generated forever.
-@var{nb_iterations} specifies the number of times the transform is
-applied to the image, and defaults to 1.
+@item test, t
-Follow some example:
-@example
-# use the default values
-ocv=dilate
+Set the number or the name of the test to perform. Supported tests are:
+@table @option
+@item dc_luma
+@item dc_chroma
+@item freq_luma
+@item freq_chroma
+@item amp_luma
+@item amp_chroma
+@item cbp
+@item mv
+@item ring1
+@item ring2
+@item all
+@end table
-# dilate using a structuring element with a 5x5 cross, iterate two times
-ocv=dilate=5x5+2x2/cross:2
+Default value is "all", which will cycle through the list of all tests.
+@end table
-# read the shape from the file diamond.shape, iterate two times
-# the file diamond.shape may contain a pattern of characters like this:
-# *
-# ***
-# *****
-# ***
-# *
-# the specified cols and rows are ignored (but not the anchor point coordinates)
-ocv=0x0+2x2/custom=diamond.shape:2
+For example the following:
+@example
+testsrc=t=dc_luma
@end example
-@subsection erode
-
-Erode an image by using a specific structuring element.
-This filter corresponds to the libopencv function @code{cvErode}.
-
-The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
-with the same syntax and semantics as the @ref{dilate} filter.
+will generate a "dc_luma" test pattern.
-@subsection smooth
+@section frei0r_src
-Smooth the input video.
+Provide a frei0r source.
-The filter takes the following parameters:
-@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
+To enable compilation of this filter you need to install the frei0r
+header and configure FFmpeg with @code{--enable-frei0r}.
-@var{type} is the type of smooth filter to apply, and can be one of
-the following values: "blur", "blur_no_scale", "median", "gaussian",
-"bilateral". The default value is "gaussian".
+The source supports the syntax:
+@example
+@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
+@end example
-@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
-parameters whose meanings depend on smooth type. @var{param1} and
-@var{param2} accept integer positive values or 0, @var{param3} and
-@var{param4} accept float values.
+@var{size} is the size of the video to generate, may be a string of the
+form @var{width}x@var{height} or a frame size abbreviation.
+@var{rate} is the rate of the video to generate, may be a string of
+the form @var{num}/@var{den} or a frame rate abbreviation.
+@var{src_name} is the name to the frei0r source to load. For more
+information regarding frei0r and how to set the parameters read the
+section @ref{frei0r} in the description of the video filters.
-The default value for @var{param1} is 3, the default value for the
-other parameters is 0.
+For example, to generate a frei0r partik0l source with size 200x200
+and frame rate 10 which is overlayed on the overlay filter main input:
+@example
+frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
+@end example
-These parameters correspond to the parameters assigned to the
-libopencv function @code{cvSmooth}.
+@section life
-@anchor{overlay}
-@section overlay
+Generate a life pattern.
-Overlay one video on top of another.
+This source is based on a generalization of John Conway's life game.
-It takes two inputs and one output, the first input is the "main"
-video on which the second input is overlayed.
+The sourced input represents a life grid, each pixel represents a cell
+which can be in one of two possible states, alive or dead. Every cell
+interacts with its eight neighbours, which are the cells that are
+horizontally, vertically, or diagonally adjacent.
-It accepts the parameters: @var{x}:@var{y}.
+At each interaction the grid evolves according to the adopted rule,
+which specifies the number of neighbor alive cells which will make a
+cell stay alive or born. The @option{rule} option allows to specify
+the rule to adopt.
-@var{x} is the x coordinate of the overlayed video on the main video,
-@var{y} is the y coordinate. The parameters are expressions containing
-the following parameters:
+This source accepts a list of options in the form of
+@var{key}=@var{value} pairs separated by ":". A description of the
+accepted options follows.
@table @option
-@item main_w, main_h
-main input width and height
+@item filename, f
+Set the file from which to read the initial grid state. In the file,
+each non-whitespace character is considered an alive cell, and newline
+is used to delimit the end of each row.
-@item W, H
-same as @var{main_w} and @var{main_h}
+If this option is not specified, the initial grid is generated
+randomly.
-@item overlay_w, overlay_h
-overlay input width and height
+@item rate, r
+Set the video rate, that is the number of frames generated per second.
+Default is 25.
+
+@item random_fill_ratio, ratio
+Set the random fill ratio for the initial random grid. It is a
+floating point number value ranging from 0 to 1, defaults to 1/PHI.
+It is ignored when a file is specified.
+
+@item random_seed, seed
+Set the seed for filling the initial random grid, must be an integer
+included between 0 and UINT32_MAX. If not specified, or if explicitly
+set to -1, the filter will try to use a good random seed on a best
+effort basis.
+
+@item rule
+Set the life rule.
+
+A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
+where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
+@var{NS} specifies the number of alive neighbor cells which make a
+live cell stay alive, and @var{NB} the number of alive neighbor cells
+which make a dead cell to become alive (i.e. to "born").
+"s" and "b" can be used in place of "S" and "B", respectively.
+
+Alternatively a rule can be specified by an 18-bits integer. The 9
+high order bits are used to encode the next cell state if it is alive
+for each number of neighbor alive cells, the low order bits specify
+the rule for "borning" new cells. Higher order bits encode for an
+higher number of neighbor cells.
+For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
+rule of 12 and a born rule of 9, which corresponds to "S23/B03".
+
+Default value is "S23/B3", which is the original Conway's game of life
+rule, and will keep a cell alive if it has 2 or 3 neighbor alive
+cells, and will born a new cell if there are three alive cells around
+a dead cell.
-@item w, h
-same as @var{overlay_w} and @var{overlay_h}
-@end table
+@item size, s
+Set the size of the output video.
-Be aware that frames are taken from each input video in timestamp
-order, hence, if their initial timestamps differ, it is a a good idea
-to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
-have them begin in the same zero timestamp, as it does the example for
-the @var{movie} filter.
+If @option{filename} is specified, the size is set by default to the
+same size of the input file. If @option{size} is set, it must contain
+the size specified in the input file, and the initial grid defined in
+that file is centered in the larger resulting area.
-Follow some examples:
-@example
-# draw the overlay at 10 pixels from the bottom right
-# corner of the main video.
-overlay=main_w-overlay_w-10:main_h-overlay_h-10
+If a filename is not specified, the size value defaults to "320x240"
+(used for a randomly generated initial grid).
-# insert a transparent PNG logo in the bottom left corner of the input
-avconv -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
+@item stitch
+If set to 1, stitch the left and right grid edges together, and the
+top and bottom edges also. Defaults to 1.
-# insert 2 different transparent PNG logos (second logo on bottom
-# right corner):
-avconv -i input -i logo1 -i logo2 -filter_complex
-'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
+@item mold
+Set cell mold speed. If set, a dead cell will go from @option{death_color} to
+@option{mold_color} with a step of @option{mold}. @option{mold} can have a
+value from 0 to 255.
-# add a transparent color layer on top of the main video,
-# WxH specifies the size of the main input to the overlay filter
-color=red@.3:WxH [over]; [in][over] overlay [out]
-@end example
+@item life_color
+Set the color of living (or new born) cells.
-You can chain together more overlays but the efficiency of such
-approach is yet to be tested.
+@item death_color
+Set the color of dead cells. If @option{mold} is set, this is the first color
+used to represent a dead cell.
-@section pad
+@item mold_color
+Set mold color, for definitely dead and moldy cells.
+@end table
-Add paddings to the input image, and places the original input at the
-given coordinates @var{x}, @var{y}.
+@subsection Examples
-It accepts the following parameters:
-@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
+@itemize
+@item
+Read a grid from @file{pattern}, and center it on a grid of size
+300x300 pixels:
+@example
+life=f=pattern:s=300x300
+@end example
-The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
-expressions containing the following constants:
+@item
+Generate a random grid of size 200x200, with a fill ratio of 2/3:
+@example
+life=ratio=2/3:s=200x200
+@end example
-@table @option
-@item E, PI, PHI
-the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), phi (golden ratio)
+@item
+Specify a custom rule for evolving a randomly generated grid:
+@example
+life=rule=S14/B34
+@end example
-@item in_w, in_h
-the input video width and height
+@item
+Full example with slow death effect (mold) using @command{ffplay}:
+@example
+ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
+@end example
+@end itemize
-@item iw, ih
-same as @var{in_w} and @var{in_h}
+@section color, nullsrc, rgbtestsrc, smptebars, testsrc
-@item out_w, out_h
-the output width and height, that is the size of the padded area as
-specified by the @var{width} and @var{height} expressions
+The @code{color} source provides an uniformly colored input.
-@item ow, oh
-same as @var{out_w} and @var{out_h}
+The @code{nullsrc} source returns unprocessed video frames. It is
+mainly useful to be employed in analysis / debugging tools, or as the
+source for filters which ignore the input data.
-@item x, y
-x and y offsets as specified by the @var{x} and @var{y}
-expressions, or NAN if not yet specified
+The @code{rgbtestsrc} source generates an RGB test pattern useful for
+detecting RGB vs BGR issues. You should see a red, green and blue
+stripe from top to bottom.
-@item a
-input display aspect ratio, same as @var{iw} / @var{ih}
+The @code{smptebars} source generates a color bars pattern, based on
+the SMPTE Engineering Guideline EG 1-1990.
-@item hsub, vsub
-horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
-@end table
+The @code{testsrc} source generates a test video pattern, showing a
+color pattern, a scrolling gradient and a timestamp. This is mainly
+intended for testing purposes.
-Follows the description of the accepted parameters.
+These sources accept an optional sequence of @var{key}=@var{value} pairs,
+separated by ":". The description of the accepted options follows.
@table @option
-@item width, height
-
-Specify the size of the output image with the paddings added. If the
-value for @var{width} or @var{height} is 0, the corresponding input size
-is used for the output.
-The @var{width} expression can reference the value set by the
-@var{height} expression, and vice versa.
+@item color, c
+Specify the color of the source, only used in the @code{color}
+source. It can be the name of a color (case insensitive match) or a
+0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
+default value is "black".
-The default value of @var{width} and @var{height} is 0.
+@item size, s
+Specify the size of the sourced video, it may be a string of the form
+@var{width}x@var{height}, or the name of a size abbreviation. The
+default value is "320x240".
-@item x, y
+@item rate, r
+Specify the frame rate of the sourced video, as the number of frames
+generated per second. It has to be a string in the format
+@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
+number or a valid video frame rate abbreviation. The default value is
+"25".
-Specify the offsets where to place the input image in the padded area
-with respect to the top/left border of the output image.
+@item sar
+Set the sample aspect ratio of the sourced video.
-The @var{x} expression can reference the value set by the @var{y}
-expression, and vice versa.
+@item duration, d
+Set the video duration of the sourced video. The accepted syntax is:
+@example
+[-]HH[:MM[:SS[.m...]]]
+[-]S+[.m...]
+@end example
+See also the function @code{av_parse_time()}.
-The default value of @var{x} and @var{y} is 0.
+If not specified, or the expressed duration is negative, the video is
+supposed to be generated forever.
-@item color
+@item decimals, n
+Set the number of decimals to show in the timestamp, only used in the
+@code{testsrc} source.
-Specify the color of the padded area, it can be the name of a color
-(case insensitive match) or a 0xRRGGBB[AA] sequence.
+The displayed timestamp value will correspond to the original
+timestamp value multiplied by the power of 10 of the specified
+value. Default value is 0.
+@end table
-The default value of @var{color} is "black".
+For example the following:
+@example
+testsrc=duration=5.3:size=qcif:rate=10
+@end example
-@end table
+will generate a video with a duration of 5.3 seconds, with size
+176x144 and a frame rate of 10 frames per second.
-Some examples follow:
+The following graph description will generate a red source
+with an opacity of 0.2, with size "qcif" and a frame rate of 10
+frames per second.
+@example
+color=c=red@@0.2:s=qcif:r=10
+@end example
+If the input content is to be ignored, @code{nullsrc} can be used. The
+following command generates noise in the luminance plane by employing
+the @code{geq} filter:
@example
-# Add paddings with color "violet" to the input video. Output video
-# size is 640x480, the top-left corner of the input video is placed at
-# column 0, row 40.
-pad=640:480:0:40:violet
+nullsrc=s=256x256, geq=random(1)*255:128:128
+@end example
-# pad the input to get an output with dimensions increased bt 3/2,
-# and put the input video at the center of the padded area
-pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
+@c man end VIDEO SOURCES
-# pad the input to get a squared output with size equal to the maximum
-# value between the input width and height, and put the input video at
-# the center of the padded area
-pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
+@chapter Video Sinks
+@c man begin VIDEO SINKS
-# pad the input to get a final w/h ratio of 16:9
-pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
+Below is a description of the currently available video sinks.
-# double output size and put the input video in the bottom-right
-# corner of the output padded area
-pad="2*iw:2*ih:ow-iw:oh-ih"
-@end example
+@section buffersink
-@section pixdesctest
+Buffer video frames, and make them available to the end of the filter
+graph.
-Pixel format descriptor test filter, mainly useful for internal
-testing. The output video should be equal to the input video.
+This sink is mainly intended for a programmatic use, in particular
+through the interface defined in @file{libavfilter/buffersink.h}.
-For example:
-@example
-format=monow, pixdesctest
-@end example
+It does not require a string parameter in input, but you need to
+specify a pointer to a list of supported pixel formats terminated by
+-1 in the opaque parameter provided to @code{avfilter_init_filter}
+when initializing this sink.
-can be used to test the monowhite pixel format descriptor definition.
+@section nullsink
-@section scale
+Null video sink, do absolutely nothing with the input video. It is
+mainly useful as a template and to be employed in analysis / debugging
+tools.
-Scale the input video to @var{width}:@var{height} and/or convert the image format.
+@c man end VIDEO SINKS
-The parameters @var{width} and @var{height} are expressions containing
-the following constants:
+@chapter Multimedia Filters
+@c man begin MULTIMEDIA FILTERS
-@table @option
-@item E, PI, PHI
-the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), phi (golden ratio)
+Below is a description of the currently available multimedia filters.
-@item in_w, in_h
-the input width and height
+@section aperms, perms
-@item iw, ih
-same as @var{in_w} and @var{in_h}
+Set read/write permissions for the output frames.
-@item out_w, out_h
-the output (cropped) width and height
+These filters are mainly aimed at developers to test direct path in the
+following filter in the filtergraph.
-@item ow, oh
-same as @var{out_w} and @var{out_h}
+The filters accept parameters as a list of @var{key}=@var{value} pairs,
+separated by ":". If the key of the first options is omitted, the argument is
+assumed to be the @var{mode}.
-@item dar, a
-input display aspect ratio, same as @var{iw} / @var{ih}
+A description of the accepted parameters follows.
-@item sar
-input sample aspect ratio
+@table @option
+@item mode
+Select the permissions mode.
-@item hsub, vsub
-horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+It accepts the following values:
+@table @samp
+@item none
+Do nothing. This is the default.
+@item ro
+Set all the output frames read-only.
+@item rw
+Set all the output frames directly writable.
+@item toggle
+Make the frame read-only if writable, and writable if read-only.
+@item random
+Set each output frame read-only or writable randomly.
@end table
-If the input image format is different from the format requested by
-the next filter, the scale filter will convert the input to the
-requested format.
+@item seed
+Set the seed for the @var{random} mode, must be an integer included between
+@code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
+@code{-1}, the filter will try to use a good random seed on a best effort
+basis.
+@end table
-If the value for @var{width} or @var{height} is 0, the respective input
-size is used for the output.
+Note: in case of auto-inserted filter between the permission filter and the
+following one, the permission might not be received as expected in that
+following filter. Inserting a @ref{format} or @ref{aformat} filter before the
+perms/aperms filter can avoid this problem.
-If the value for @var{width} or @var{height} is -1, the scale filter will
-use, for the respective output size, a value that maintains the aspect
-ratio of the input image.
+@section aphaser
+Add a phasing effect to the input audio.
-The default value of @var{width} and @var{height} is 0.
+A phaser filter creates series of peaks and troughs in the frequency spectrum.
+The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
-Some examples follow:
-@example
-# scale the input video to a size of 200x100.
-scale=200:100
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":".
-# scale the input to 2x
-scale=2*iw:2*ih
-# the above is the same as
-scale=2*in_w:2*in_h
+A description of the accepted parameters follows.
-# scale the input to half size
-scale=iw/2:ih/2
+@table @option
+@item in_gain
+Set input gain. Default is 0.4.
-# increase the width, and set the height to the same size
-scale=3/2*iw:ow
+@item out_gain
+Set output gain. Default is 0.74
-# seek for Greek harmony
-scale=iw:1/PHI*iw
-scale=ih*PHI:ih
+@item delay
+Set delay in milliseconds. Default is 3.0.
-# increase the height, and set the width to 3/2 of the height
-scale=3/2*oh:3/5*ih
+@item decay
+Set decay. Default is 0.4.
-# increase the size, but make the size a multiple of the chroma
-scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
+@item speed
+Set modulation speed in Hz. Default is 0.5.
-# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
-scale='min(500\, iw*3/2):-1'
-@end example
+@item type
+Set modulation type. Default is triangular.
+
+It accepts the following values:
+@table @samp
+@item triangular, t
+@item sinusoidal, s
+@end table
+@end table
-@section select
+@section aselect, select
Select frames to pass in output.
-It accepts in input an expression, which is evaluated for each input
-frame. If the expression is evaluated to a non-zero value, the frame
-is selected and passed to the output, otherwise it is discarded.
+These filters accept a single option @option{expr} or @option{e}
+specifying the select expression, which can be specified either by
+specyfing @code{expr=VALUE} or specifying the expression
+alone.
+
+The select expression is evaluated for each input frame. If the
+evaluation result is a non-zero value, the frame is selected and
+passed to the output, otherwise it is discarded.
The expression can contain the following constants:
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