cycles, and there can be multiple links between a pair of
filters. Each link has one input pad on one side connecting it to one
filter from which it takes its input, and one output pad on the other
-side connecting it to the one filter accepting its output.
+side connecting it to one filter accepting its output.
Each filter in a filtergraph is an instance of a filter class
registered in the application, which defines the features and the
number of input and output pads of the filter.
-A filter with no input pads is called a "source", a filter with no
+A filter with no input pads is called a "source", and a filter with no
output pads is called a "sink".
+@anchor{Filtergraph syntax}
@section Filtergraph syntax
-A filtergraph can be represented using a textual representation, which
-is recognized by the @code{-vf} and @code{-af} options of the ff*
-tools, and by the @code{av_parse_graph()} function defined in
-@file{libavfilter/avfiltergraph}.
+A filtergraph has a textual representation, which is
+recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
+options in @command{avconv} and @option{-vf} in @command{avplay}, and by the
+@code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} functions defined in
+@file{libavfilter/avfilter.h}.
A filterchain consists of a sequence of connected filters, each one
connected to the previous one in the sequence. A filterchain is
"=@var{arguments}".
@var{arguments} is a string which contains the parameters used to
-initialize the filter instance, and are described in the filter
-descriptions below.
+initialize the filter instance. It may have one of two forms:
+@itemize
+
+@item
+A ':'-separated list of @var{key=value} pairs.
+
+@item
+A ':'-separated list of @var{value}. In this case, the keys are assumed to be
+the option names in the order they are declared. E.g. the @code{fade} filter
+declares three options in this order -- @option{type}, @option{start_frame} and
+@option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
+@var{in} is assigned to the option @option{type}, @var{0} to
+@option{start_frame} and @var{30} to @option{nb_frames}.
+
+@end itemize
+
+If the option value itself is a list of items (e.g. the @code{format} filter
+takes a list of pixel formats), the items in the list are usually separated by
+'|'.
The list of arguments can be quoted using the character "'" as initial
and ending mark, and the character '\' for escaping the characters
If an output pad is not labelled, it is linked by default to the first
unlabelled input pad of the next filter in the filterchain.
-For example in the filterchain:
+For example in the filterchain
@example
nullsrc, split[L1], [L2]overlay, nullsink
@end example
pads must be connected. A filtergraph is considered valid if all the
filter input and output pads of all the filterchains are connected.
-Follows a BNF description for the filtergraph syntax:
+Libavfilter will automatically insert @ref{scale} filters where format
+conversion is required. It is possible to specify swscale flags
+for those automatically inserted scalers by prepending
+@code{sws_flags=@var{flags};}
+to the filtergraph description.
+
+Here is a BNF description of the filtergraph syntax:
@example
@var{NAME} ::= sequence of alphanumeric characters and '_'
@var{LINKLABEL} ::= "[" @var{NAME} "]"
@var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
-@var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
-@var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
+@var{FILTER_ARGUMENTS} ::= sequence of chars (possibly quoted)
+@var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
@var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
-@var{FILTERGRAPH} ::= @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
+@var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
@end example
@c man end FILTERGRAPH DESCRIPTION
@chapter Audio Filters
@c man begin AUDIO FILTERS
-When you configure your FFmpeg build, you can disable any of the
+When you configure your Libav build, you can disable any of the
existing filters using --disable-filters.
The configure output will show the audio filters included in your
build.
Below is a description of the currently available audio filters.
-@section anull
+@section aformat
-Pass the audio source unchanged to the output.
+Convert the input audio to one of the specified formats. The framework will
+negotiate the most appropriate format to minimize conversions.
-@c man end AUDIO FILTERS
+It accepts the following parameters:
+@table @option
-@chapter Audio Sources
-@c man begin AUDIO SOURCES
+@item sample_fmts
+A '|'-separated list of requested sample formats.
-Below is a description of the currently available audio sources.
+@item sample_rates
+A '|'-separated list of requested sample rates.
-@section anullsrc
+@item channel_layouts
+A '|'-separated list of requested channel layouts.
-Null audio source, never return audio frames. It is mainly useful as a
-template and to be employed in analysis / debugging tools.
+@end table
-It accepts as optional parameter a string of the form
-@var{sample_rate}:@var{channel_layout}.
+If a parameter is omitted, all values are allowed.
-@var{sample_rate} specify the sample rate, and defaults to 44100.
+Force the output to either unsigned 8-bit or signed 16-bit stereo
+@example
+aformat=sample_fmts=u8|s16:channel_layouts=stereo
+@end example
-@var{channel_layout} specify the channel layout, and can be either an
-integer or a string representing a channel layout. The default value
-of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
+@section amix
-Check the channel_layout_map definition in
-@file{libavcodec/audioconvert.c} for the mapping between strings and
-channel layout values.
+Mixes multiple audio inputs into a single output.
-Follow some examples:
+For example
@example
-# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
-anullsrc=48000:4
-
-# same as
-anullsrc=48000:mono
+avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
@end example
+will mix 3 input audio streams to a single output with the same duration as the
+first input and a dropout transition time of 3 seconds.
-@c man end AUDIO SOURCES
+It accepts the following parameters:
+@table @option
-@chapter Audio Sinks
-@c man begin AUDIO SINKS
+@item inputs
+The number of inputs. If unspecified, it defaults to 2.
-Below is a description of the currently available audio sinks.
+@item duration
+How to determine the end-of-stream.
+@table @option
-@section anullsink
+@item longest
+The duration of the longest input. (default)
-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.
+@item shortest
+The duration of the shortest input.
-@c man end AUDIO SINKS
+@item first
+The duration of the first input.
-@chapter Video Filters
-@c man begin VIDEO FILTERS
+@end table
-When you configure your FFmpeg build, you can disable any of the
-existing filters using --disable-filters.
-The configure output will show the video filters included in your
-build.
+@item dropout_transition
+The transition time, in seconds, for volume renormalization when an input
+stream ends. The default value is 2 seconds.
-Below is a description of the currently available video filters.
+@end table
-@section blackframe
+@section anull
-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.
+Pass the audio source unchanged to the output.
-In order to display the output lines, you need to set the loglevel at
-least to the AV_LOG_INFO value.
+@section asetpts
-The filter accepts the syntax:
-@example
-blackframe[=@var{amount}:[@var{threshold}]]
-@end example
+Change the PTS (presentation timestamp) of the input audio frames.
-@var{amount} is the percentage of the pixels that have to be below the
-threshold, and defaults to 98.
+It accepts the following parameters:
-@var{threshold} is the threshold below which a pixel value is
-considered black, and defaults to 32.
+@table @option
-@section crop
+@item expr
+The expression which is evaluated for each frame to construct its timestamp.
-Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
+@end table
-The parameters are expressions containing the following constants:
+The expression is evaluated through the eval API and can contain the following
+constants:
@table @option
+@item FRAME_RATE
+frame rate, only defined for constant frame-rate video
+
+@item PTS
+the presentation timestamp in input
+
@item E, PI, PHI
-the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), PHI (golden ratio)
+These are approximated values for the mathematical constants e
+(Euler's number), pi (Greek pi), and phi (the golden ratio).
-@item x, y
-the computed values for @var{x} and @var{y}. They are evaluated for
-each new frame.
+@item N
+The number of audio samples passed through the filter so far, starting at 0.
-@item in_w, in_h
-the input width and heigth
+@item S
+The number of audio samples in the current frame.
-@item iw, ih
-same as @var{in_w} and @var{in_h}
+@item SR
+The audio sample rate.
-@item out_w, out_h
-the output (cropped) width and heigth
+@item STARTPTS
+The PTS of the first frame.
-@item ow, oh
-same as @var{out_w} and @var{out_h}
+@item PREV_INPTS
+The previous input PTS.
-@item n
-the number of input frame, starting from 0
+@item PREV_OUTPTS
+The previous output PTS.
-@item pos
-the position in the file of the input frame, NAN if unknown
+@item RTCTIME
+The wallclock (RTC) time in microseconds.
-@item t
-timestamp expressed in seconds, NAN if the input timestamp is unknown
+@item RTCSTART
+The wallclock (RTC) time at the start of the movie in microseconds.
@end table
-The @var{out_w} and @var{out_h} parameters specify the expressions for
-the width and height of the output (cropped) video. They are
-evaluated just at the configuration of the filter.
+Some examples:
-The default value of @var{out_w} is "in_w", and the default value of
-@var{out_h} is "in_h".
+@example
+# Start counting PTS from zero
+asetpts=expr=PTS-STARTPTS
-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}.
+# Generate timestamps by counting samples
+asetpts=expr=N/SR/TB
-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.
+# Generate timestamps from a "live source" and rebase onto the current timebase
+asetpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
+@end example
-The default value of @var{x} is "(in_w-out_w)/2", and the default
-value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
-the center of the input image.
+@section asettb
-The expression for @var{x} may depend on @var{y}, and the expression
-for @var{y} may depend on @var{x}.
+Set the timebase to use for the output frames timestamps.
+It is mainly useful for testing timebase configuration.
-Follow some examples:
-@example
-# crop the central input area with size 100x100
-crop=100:100
+This filter accepts the following parameters:
-# crop the central input area with size 2/3 of the input video
-"crop=2/3*in_w:2/3*in_h"
+@table @option
-# crop the input video central square
-crop=in_h
+@item expr
+The expression which is evaluated into the output timebase.
-# 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.
-crop=in_w-100:in_h-100:100:100
+@end table
-# crop 10 pixels from the lefth and right borders, and 20 pixels from
-# the top and bottom borders
-"crop=in_w-2*10:in_h-2*20"
+The expression can contain the constants @var{PI}, @var{E}, @var{PHI}, @var{AVTB} (the
+default timebase), @var{intb} (the input timebase), and @var{sr} (the sample rate,
+audio only).
-# keep only the bottom right quarter of the input image
-"crop=in_w/2:in_h/2:in_w/2:in_h/2"
+The default value for the input is @var{intb}.
-# crop height for getting Greek harmony
-"crop=in_w:1/PHI*in_w"
+Some examples:
-# trembling effect
-"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)"
+@example
+# Set the timebase to 1/25:
+settb=1/25
-# erratic camera effect depending on timestamp and position
-"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)"
+# Set the timebase to 1/10:
+settb=0.1
-# set x depending on the value of y
-"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
+# Set the timebase to 1001/1000:
+settb=1+0.001
+
+# Set the timebase to 2*intb:
+settb=2*intb
+
+# Set the default timebase value:
+settb=AVTB
+
+# Set the timebase to twice the sample rate:
+asettb=sr*2
@end example
-@section cropdetect
+@section ashowinfo
-Auto-detect crop size.
+Show a line containing various information for each input audio frame.
+The input audio is not modified.
-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 shown line contains a sequence of key/value pairs of the form
+@var{key}:@var{value}.
-It accepts the syntax:
-@example
-cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
-@end example
+It accepts the following parameters:
@table @option
+@item n
+The (sequential) number of the input frame, starting from 0.
-@item limit
-Threshold, which can be optionally specified from nothing (0) to
-everything (255), defaults to 24.
+@item pts
+The presentation timestamp of the input frame, in time base units; the time base
+depends on the filter input pad, and is usually 1/@var{sample_rate}.
-@item round
-Value which the width/height should be divisible by, defaults to
-16. 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.
+@item pts_time
+The presentation timestamp of the input frame in seconds.
-@item reset
-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. Defaults to 0.
+@item fmt
+The sample format.
-This can be useful when channel logos distort the video area. 0
-indicates never reset and return the largest area encountered during
-playback.
+@item chlayout
+The channel layout.
+
+@item rate
+The sample rate for the audio frame.
+
+@item nb_samples
+The number of samples (per channel) in the frame.
+
+@item checksum
+The Adler-32 checksum (printed in hexadecimal) of the audio data. For planar
+audio, the data is treated as if all the planes were concatenated.
+
+@item plane_checksums
+A list of Adler-32 checksums for each data plane.
@end table
-@section drawbox
+@section asplit
-Draw a colored box on the input image.
+Split input audio into several identical outputs.
+
+It accepts a single parameter, which specifies the number of outputs. If
+unspecified, it defaults to 2.
-It accepts the syntax:
+For example,
@example
-drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
+avconv -i INPUT -filter_complex asplit=5 OUTPUT
@end example
+will create 5 copies of the input audio.
+@section asyncts
+Synchronize audio data with timestamps by squeezing/stretching it and/or
+dropping samples/adding silence when needed.
+
+It accepts the following parameters:
@table @option
-@item x, y
-Specify the top left corner coordinates of the box. Default to 0.
+@item compensate
+Enable stretching/squeezing the data to make it match the timestamps. Disabled
+by default. When disabled, time gaps are covered with silence.
-@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.
+@item min_delta
+The minimum difference between timestamps and audio data (in seconds) to trigger
+adding/dropping samples. The default value is 0.1. If you get an imperfect
+sync with this filter, try setting this parameter to 0.
-@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.
+@item max_comp
+The maximum compensation in samples per second. Only relevant with compensate=1.
+The default value is 500.
+
+@item first_pts
+Assume that the first PTS should be this value. The time base is 1 / sample
+rate. This allows for padding/trimming at the start of the stream. By default,
+no assumption is made about the first frame's expected PTS, so no padding or
+trimming is done. For example, this could be set to 0 to pad the beginning with
+silence if an audio stream starts after the video stream or to trim any samples
+with a negative PTS due to encoder delay.
+
+@end table
+
+@section atrim
+Trim the input so that the output contains one continuous subpart of the input.
+
+It accepts the following parameters:
+@table @option
+@item start
+Timestamp (in seconds) of the start of the section to keep. I.e. the audio
+sample with the timestamp @var{start} will be the first sample in the output.
+
+@item end
+Timestamp (in seconds) of the first audio sample that will be dropped. I.e. the
+audio sample immediately preceding the one with the timestamp @var{end} will be
+the last sample in the output.
+
+@item start_pts
+Same as @var{start}, except this option sets the start timestamp in samples
+instead of seconds.
+
+@item end_pts
+Same as @var{end}, except this option sets the end timestamp in samples instead
+of seconds.
+
+@item duration
+The maximum duration of the output in seconds.
+
+@item start_sample
+The number of the first sample that should be output.
+
+@item end_sample
+The number of the first sample that should be dropped.
@end table
-Follow some examples:
+Note that the first two sets of the start/end options and the @option{duration}
+option look at the frame timestamp, while the _sample options simply count the
+samples that pass through the filter. So start/end_pts and start/end_sample will
+give different results when the timestamps are wrong, inexact or do not start at
+zero. Also note that this filter does not modify the timestamps. If you wish
+to have the output timestamps start at zero, insert the asetpts filter after the
+atrim filter.
+
+If multiple start or end options are set, this filter tries to be greedy and
+keep all samples that match at least one of the specified constraints. To keep
+only the part that matches all the constraints at once, chain multiple atrim
+filters.
+
+The defaults are such that all the input is kept. So it is possible to set e.g.
+just the end values to keep everything before the specified time.
+
+Examples:
+@itemize
+@item
+Drop everything except the second minute of input:
@example
-# draw a black box around the edge of the input image
-drawbox
+avconv -i INPUT -af atrim=60:120
+@end example
-# draw a box with color red and an opacity of 50%
-drawbox=10:20:200:60:red@@0.5"
+@item
+Keep only the first 1000 samples:
+@example
+avconv -i INPUT -af atrim=end_sample=1000
@end example
-@section fifo
+@end itemize
-Buffer input images and send them when they are requested.
+@section bs2b
+Bauer stereo to binaural transformation, which improves headphone listening of
+stereo audio records.
-This filter is mainly useful when auto-inserted by the libavfilter
-framework.
+It accepts the following parameters:
+@table @option
-The filter does not take parameters.
+@item profile
+Pre-defined crossfeed level.
+@table @option
-@section format
+@item default
+Default level (fcut=700, feed=50).
-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.
+@item cmoy
+Chu Moy circuit (fcut=700, feed=60).
+
+@item jmeier
+Jan Meier circuit (fcut=650, feed=95).
+
+@end table
+
+@item fcut
+Cut frequency (in Hz).
+
+@item feed
+Feed level (in Hz).
+
+@end table
+
+@section channelsplit
+Split each channel from an input audio stream into a separate output stream.
-The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
+It accepts the following parameters:
+@table @option
+@item channel_layout
+The channel layout of the input stream. The default is "stereo".
+@end table
-The following command:
+For example, assuming a stereo input MP3 file,
+@example
+avconv -i in.mp3 -filter_complex channelsplit out.mkv
+@end example
+will create an output Matroska file with two audio streams, one containing only
+the left channel and the other the right channel.
+Split a 5.1 WAV file into per-channel files:
@example
-./ffmpeg -i in.avi -vf "format=yuv420p" out.avi
+avconv -i in.wav -filter_complex
+'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
+-map '[FL]' front_left.wav -map '[FR]' front_right.wav
+-map '[FC]' front_center.wav -map '[LFE]' low_frequency_effects.wav
+-map '[SL]' side_left.wav -map '[SR]' side_right.wav
@end example
-will convert the input video to the format "yuv420p".
+@section channelmap
+Remap input channels to new locations.
-@anchor{frei0r}
-@section frei0r
+It accepts the following parameters:
+@table @option
+@item channel_layout
+The channel layout of the output stream.
+
+@item map
+Map channels from input to output. The argument is a '|'-separated list of
+mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
+@var{in_channel} form. @var{in_channel} can be either the name of the input
+channel (e.g. FL for front left) or its index in the input channel layout.
+@var{out_channel} is the name of the output channel or its index in the output
+channel layout. If @var{out_channel} is not given then it is implicitly an
+index, starting with zero and increasing by one for each mapping.
+@end table
-Apply a frei0r effect to the input video.
+If no mapping is present, the filter will implicitly map input channels to
+output channels, preserving indices.
-To enable compilation of this filter you need to install the frei0r
-header and configure FFmpeg with --enable-frei0r.
+For example, assuming a 5.1+downmix input MOV file,
+@example
+avconv -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
+@end example
+will create an output WAV file tagged as stereo from the downmix channels of
+the input.
-The filter supports the syntax:
+To fix a 5.1 WAV improperly encoded in AAC's native channel order
@example
-@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
+avconv -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav
@end example
-@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/}.
+@section compand
+Compress or expand the audio's dynamic range.
+
+It accepts the following parameters:
+
+@table @option
-@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
-for the frei0r effect.
+@item attacks
+@item decays
+A list of times in seconds for each channel over which the instantaneous level
+of the input signal is averaged to determine its volume. @var{attacks} refers to
+increase of volume and @var{decays} refers to decrease of volume. For most
+situations, the attack time (response to the audio getting louder) should be
+shorter than the decay time, because the human ear is more sensitive to sudden
+loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
+a typical value for decay is 0.8 seconds.
+
+@item points
+A list of points for the transfer function, specified in dB relative to the
+maximum possible signal amplitude. Each key points list must be defined using
+the following syntax: @code{x0/y0|x1/y1|x2/y2|....}
+
+The input values must be in strictly increasing order but the transfer function
+does not have to be monotonically rising. The point @code{0/0} is assumed but
+may be overridden (by @code{0/out-dBn}). Typical values for the transfer
+function are @code{-70/-70|-60/-20}.
+
+@item soft-knee
+Set the curve radius in dB for all joints. It defaults to 0.01.
+
+@item gain
+Set the additional gain in dB to be applied at all points on the transfer
+function. This allows for easy adjustment of the overall gain.
+It defaults to 0.
+
+@item volume
+Set an initial volume, in dB, to be assumed for each channel when filtering
+starts. This permits the user to supply a nominal level initially, so that, for
+example, a very large gain is not applied to initial signal levels before the
+companding has begun to operate. A typical value for audio which is initially
+quiet is -90 dB. It defaults to 0.
+
+@item delay
+Set a delay, in seconds. The input audio is analyzed immediately, but audio is
+delayed before being fed to the volume adjuster. Specifying a delay
+approximately equal to the attack/decay times allows the filter to effectively
+operate in predictive rather than reactive mode. It defaults to 0.
-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.
+@end table
-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
-Some examples follow:
+@itemize
+@item
+Make music with both quiet and loud passages suitable for listening to in a
+noisy environment:
@example
-# apply the distort0r effect, set the first two double parameters
-frei0r=distort0r:0.5:0.01
+compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
+@end example
-# apply the colordistance effect, takes a color as first parameter
-frei0r=colordistance:0.2/0.3/0.4
-frei0r=colordistance:violet
-frei0r=colordistance:0x112233
+@item
+A noise gate for when the noise is at a lower level than the signal:
+@example
+compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
+@end example
-# apply the perspective effect, specify the top left and top right
-# image positions
-frei0r=perspective:0.2/0.2:0.8/0.2
+@item
+Here is another noise gate, this time for when the noise is at a higher level
+than the signal (making it, in some ways, similar to squelch):
+@example
+compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
@end example
+@end itemize
-For more information see:
-@url{http://piksel.org/frei0r}
+@section join
+Join multiple input streams into one multi-channel stream.
-@section gradfun
+It accepts the following parameters:
+@table @option
-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 inputs
+The number of input streams. It defaults to 2.
-The filter takes two optional parameters, separated by ':':
-@var{strength}:@var{radius}
+@item channel_layout
+The desired output channel layout. It defaults to stereo.
-@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 255, default value is
-1.2, out-of-range values will be clipped to the valid range.
+@item map
+Map channels from inputs to output. The argument is a '|'-separated list of
+mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
+form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
+can be either the name of the input channel (e.g. FL for front left) or its
+index in the specified input stream. @var{out_channel} is the name of the output
+channel.
+@end table
-@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.
+The filter will attempt to guess the mappings when they are not specified
+explicitly. It does so by first trying to find an unused matching input channel
+and if that fails it picks the first unused input channel.
+Join 3 inputs (with properly set channel layouts):
@example
-# default parameters
-gradfun=1.2:16
+avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
+@end example
-# omitting radius
-gradfun=1.2
+Build a 5.1 output from 6 single-channel streams:
+@example
+avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
+'join=inputs=6:channel_layout=5.1:map=0.0-FL|1.0-FR|2.0-FC|3.0-SL|4.0-SR|5.0-LFE'
+out
@end example
-@section hflip
+@section hdcd
-Flip the input video horizontally.
+Decodes High Definition Compatible Digital (HDCD) data. A 16-bit PCM stream with
+embedded HDCD codes is expanded into a 20-bit PCM stream.
+
+The filter supports the Peak Extend and Low-level Gain Adjustment features
+of HDCD, and detects the Transient Filter flag.
-For example to horizontally flip the video in input with
-@file{ffmpeg}:
@example
-ffmpeg -i in.avi -vf "hflip" out.avi
+avconv -i HDCD16.flac -af hdcd OUT24.flac
@end example
-@section hqdn3d
+When using the filter with WAV, note that the default encoding for WAV is 16-bit,
+so the resulting 20-bit stream will be truncated back to 16-bit. Use something
+like @command{-acodec pcm_s24le} after the filter to get 24-bit PCM output.
+@example
+avconv -i HDCD16.wav -af hdcd OUT16.wav
+avconv -i HDCD16.wav -af hdcd -acodec pcm_s24le OUT24.wav
+@end example
-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.
+The filter accepts the following options:
-It accepts the following optional parameters:
-@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
+@table @option
+@item analyze_mode
+Replace audio with a solid tone and adjust the amplitude to signal some
+specific aspect of the decoding process. The output file can be loaded in
+an audio editor alongside the original to aid analysis.
+Modes are:
+@table @samp
+@item 0, off
+Disabled
+@item 1, lle
+Gain adjustment level at each sample
+@item 2, pe
+Samples where peak extend occurs
+@item 3, cdt
+Samples where the code detect timer is active
+@item 4, tgm
+Samples where the target gain does not match between channels
+@item 5, pel
+Any samples above peak extend level
+@item 6, ltgm
+Gain adjustment level at each sample, in each channel
+@end table
+@end table
+
+@section resample
+Convert the audio sample format, sample rate and channel layout. It is
+not meant to be used directly; it is inserted automatically by libavfilter
+whenever conversion is needed. Use the @var{aformat} filter to force a specific
+conversion.
+
+@section volume
+
+Adjust the input audio volume.
+
+It accepts the following parameters:
@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 volume
+This expresses how the audio volume will be increased or decreased.
-@item luma_tmp
-a float number which specifies luma temporal strength, defaults to
-6.0*@var{luma_spatial}/4.0
+Output values are clipped to the maximum value.
+
+The output audio volume is given by the relation:
+@example
+@var{output_volume} = @var{volume} * @var{input_volume}
+@end example
+
+The default value for @var{volume} is 1.0.
+
+@item precision
+This parameter represents the mathematical precision.
+
+It determines which input sample formats will be allowed, which affects the
+precision of the volume scaling.
+
+@table @option
+@item fixed
+8-bit fixed-point; this limits input sample format to U8, S16, and S32.
+@item float
+32-bit floating-point; this limits input sample format to FLT. (default)
+@item double
+64-bit floating-point; this limits input sample format to DBL.
+@end table
+
+@item replaygain
+Choose the behaviour on encountering ReplayGain side data in input frames.
+
+@table @option
+@item drop
+Remove ReplayGain side data, ignoring its contents (the default).
+
+@item ignore
+Ignore ReplayGain side data, but leave it in the frame.
+
+@item track
+Prefer the track gain, if present.
+
+@item album
+Prefer the album gain, if present.
+@end table
+
+@item replaygain_preamp
+Pre-amplification gain in dB to apply to the selected replaygain gain.
+
+Default value for @var{replaygain_preamp} is 0.0.
+
+@item replaygain_noclip
+Prevent clipping by limiting the gain applied.
+
+Default value for @var{replaygain_noclip} is 1.
-@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 noformat
+@subsection Examples
+
+@itemize
+@item
+Halve the input audio volume:
+@example
+volume=volume=0.5
+volume=volume=1/2
+volume=volume=-6.0206dB
+@end example
+
+@item
+Increase input audio power by 6 decibels using fixed-point precision:
+@example
+volume=volume=6dB:precision=fixed
+@end example
+@end itemize
+
+@c man end AUDIO FILTERS
+
+@chapter Audio Sources
+@c man begin AUDIO SOURCES
+
+Below is a description of the currently available audio sources.
+
+@section anullsrc
+
+The null audio source; it never returns audio frames. It is mainly useful as a
+template and for use in analysis / debugging tools.
+
+It accepts, as an optional parameter, a string of the form
+@var{sample_rate}:@var{channel_layout}.
+
+@var{sample_rate} specifies the sample rate, and defaults to 44100.
+
+@var{channel_layout} specifies the channel layout, and can be either an
+integer or a string representing a channel layout. The default value
+of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
+
+Check the channel_layout_map definition in
+@file{libavutil/channel_layout.c} for the mapping between strings and
+channel layout values.
+
+Some examples:
+@example
+# Set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO
+anullsrc=48000:4
+
+# The same as above
+anullsrc=48000:mono
+@end example
+
+@section abuffer
+Buffer audio frames, and make them available to the filter chain.
+
+This source is not intended to be part of user-supplied graph descriptions; it
+is for insertion by calling programs, through the interface defined in
+@file{libavfilter/buffersrc.h}.
+
+It accepts the following parameters:
+@table @option
+
+@item time_base
+The timebase which will be used for timestamps of submitted frames. It must be
+either a floating-point number or in @var{numerator}/@var{denominator} form.
+
+@item sample_rate
+The audio sample rate.
+
+@item sample_fmt
+The name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
+
+@item channel_layout
+The channel layout of the audio data, in the form that can be accepted by
+@code{av_get_channel_layout()}.
+@end table
+
+All the parameters need to be explicitly defined.
+
+@c man end AUDIO SOURCES
+
+@chapter Audio Sinks
+@c man begin AUDIO SINKS
+
+Below is a description of the currently available audio sinks.
+
+@section anullsink
+
+Null audio sink; do absolutely nothing with the input audio. It is
+mainly useful as a template and for use in analysis / debugging
+tools.
+
+@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}.
+
+It does not accept any parameters.
+
+@c man end AUDIO SINKS
+
+@chapter Video Filters
+@c man begin VIDEO FILTERS
+
+When you configure your Libav build, you can disable any of the
+existing filters using --disable-filters.
+The configure output will show the video filters included in your
+build.
+
+Below is a description of the currently available video filters.
+
+@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.
+
+It accepts the following parameters:
+
+@table @option
+
+@item amount
+The percentage of the pixels that have to be below the threshold; it defaults to
+98.
+
+@item threshold
+The threshold below which a pixel value is considered black; it defaults to 32.
+
+@end table
+
+@section boxblur
+
+Apply a boxblur algorithm to the input video.
+
+It accepts the following parameters:
+
+@table @option
+
+@item luma_radius
+@item luma_power
+@item chroma_radius
+@item chroma_power
+@item alpha_radius
+@item alpha_power
+
+@end table
+
+The chroma and alpha parameters are optional. If not specified, they default
+to the corresponding values set for @var{luma_radius} and
+@var{luma_power}.
+
+@var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
+the radius in pixels of the box used for blurring the corresponding
+input plane. They are expressions, and 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
+The 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 radius 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.
+
+@var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
+how many times the boxblur filter is applied to the corresponding
+plane.
+
+Some examples:
+
+@itemize
+
+@item
+Apply a boxblur filter with the luma, chroma, and alpha radii
+set to 2:
+@example
+boxblur=luma_radius=2:luma_power=1
+@end example
+
+@item
+Set the luma radius to 2, and alpha and chroma radius to 0:
+@example
+boxblur=2:1:0:0:0:0
+@end example
+
+@item
+Set the luma and chroma radii to a fraction of the video dimension:
+@example
+boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
+@end example
+
+@end itemize
+
+@section copy
+
+Copy the input source unchanged to the output. This is mainly useful for
+testing purposes.
+
+@section crop
+
+Crop the input video to given dimensions.
+
+It accepts the following parameters:
+
+@table @option
+
+@item out_w
+The width of the output video.
+
+@item out_h
+The height of the output video.
+
+@item x
+The horizontal position, in the input video, of the left edge of the output
+video.
+
+@item y
+The vertical position, in the input video, of the top edge of the output video.
+
+@end table
+
+The parameters are expressions containing the following constants:
+
+@table @option
+@item E, PI, PHI
+These are approximated values for the mathematical constants e
+(Euler's number), pi (Greek pi), and phi (the golden ratio).
+
+@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
+These are the same as @var{in_w} and @var{in_h}.
+
+@item out_w, out_h
+The output (cropped) width and height.
+
+@item ow, oh
+These are the same as @var{out_w} and @var{out_h}.
+
+@item n
+The number of the input frame, starting from 0.
+
+@item t
+The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
+
+@end table
+
+The @var{out_w} and @var{out_h} parameters specify the expressions for
+the width and height of the output (cropped) video. They are only
+evaluated during the configuration of the filter.
+
+The default value of @var{out_w} is "in_w", and the default value of
+@var{out_h} is "in_h".
+
+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 default value of @var{x} is "(in_w-out_w)/2", and the default
+value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
+the center of the input image.
+
+The expression for @var{x} may depend on @var{y}, and the expression
+for @var{y} may depend on @var{x}.
+
+Some examples:
+@example
+# Crop the central input area with size 100x100
+crop=out_w=100:out_h=100
+
+# Crop the central input area with size 2/3 of the input video
+"crop=out_w=2/3*in_w:out_h=2/3*in_h"
+
+# Crop the input video central square
+crop=out_w=in_h
+
+# 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
+crop=out_w=in_w-100:out_h=in_h-100:x=100:y=100
+
+# Crop 10 pixels from the left and right borders, and 20 pixels from
+# the top and bottom borders
+"crop=out_w=in_w-2*10:out_h=in_h-2*20"
+
+# Keep only the bottom right quarter of the input image
+"crop=out_w=in_w/2:out_h=in_h/2:x=in_w/2:y=in_h/2"
+
+# Crop height for getting Greek harmony
+"crop=out_w=in_w:out_h=1/PHI*in_w"
+
+# Trembling effect
+"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)"
+
+# Erratic camera effect depending on timestamp
+"crop=out_w=in_w/2:out_h=in_h/2:x=(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):y=(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
+
+# Set x depending on the value of y
+"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
+@end example
+
+@section cropdetect
+
+Auto-detect the crop size.
+
+It calculates the necessary cropping parameters and prints the
+recommended parameters via the logging system. The detected dimensions
+correspond to the non-black area of the input video.
+
+It accepts the following parameters:
+
+@table @option
+
+@item limit
+The threshold, an optional parameter between nothing (0) and
+everything (255). It defaults to 24.
+
+@item round
+The value which the width/height should be divisible by. It defaults to
+16. 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.
+
+@item reset
+A counter that determines how many frames cropdetect will reset
+the previously detected largest video area after. It will then start over
+and detect the current optimal crop area. It defaults to 0.
+
+This can be useful when channel logos distort the video area. 0
+indicates 'never reset', and returns the largest area encountered during
+playback.
+@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).
+
+It accepts the following parameters:
+@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
+
+An example:
+
+@itemize
+
+@item
+Set a rectangle covering the area with top left corner coordinates 0,0
+and size 100x77, and a band of size 10:
+@example
+delogo=x=0:y=0:w=100:h=77:band=10
+@end example
+
+@end itemize
+
+@section drawbox
+
+Draw a colored box on the input image.
+
+It accepts the following parameters:
+
+@table @option
+
+@item x, y
+Specify the top left corner coordinates of the box. It defaults to 0.
+
+@item width, height
+Specify the width and height of the box; if 0 they are interpreted as
+the input width and height. It defaults to 0.
+
+@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
+
+Some examples:
+@example
+# Draw a black box around the edge of the input image
+drawbox
+
+# Draw a box with color red and an opacity of 50%
+drawbox=x=10:y=20:width=200:height=60:color=red@@0.5"
+@end example
+
+@section drawtext
+
+Draw a text string or text from a specified file on top of a video, using the
+libfreetype library.
+
+To enable compilation of this filter, you need to configure Libav with
+@code{--enable-libfreetype}.
+To enable default font fallback and the @var{font} option you need to
+configure Libav with @code{--enable-libfontconfig}.
+
+The filter also recognizes strftime() sequences in the provided text
+and expands them accordingly. Check the documentation of strftime().
+
+It accepts the following parameters:
+
+@table @option
+
+@item font
+The font family to be used for drawing text. By default Sans.
+
+@item fontfile
+The font file to be used for drawing text. The path must be included.
+This parameter is mandatory if the fontconfig support is disabled.
+
+@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 text and textfile are specified, an error is thrown.
+
+@item x, y
+The offsets where text will be drawn within the video frame.
+It is relative to the top/left border of the output image.
+They accept expressions similar to the @ref{overlay} filter:
+@table @option
+
+@item x, y
+The computed values for @var{x} and @var{y}. They are evaluated for
+each new frame.
+
+@item main_w, main_h
+The main input width and height.
+
+@item W, H
+These are the same as @var{main_w} and @var{main_h}.
+
+@item text_w, text_h
+The rendered text's width and height.
+
+@item w, h
+These are the same as @var{text_w} and @var{text_h}.
+
+@item n
+The number of frames processed, starting from 0.
+
+@item t
+The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
+
+@end table
+
+The default value of @var{x} and @var{y} is 0.
+
+@item draw
+Draw the text only if the expression evaluates as non-zero.
+The expression accepts the same variables @var{x, y} do.
+The default value is 1.
+
+@item alpha
+Draw the text applying alpha blending. The value can
+be either a number between 0.0 and 1.0
+The expression accepts the same variables @var{x, y} do.
+The default value is 1.
+
+@item fontsize
+The font size to be used for drawing text.
+The default value of @var{fontsize} is 16.
+
+@item fontcolor
+The color to be used for drawing fonts.
+It is 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 boxcolor
+The color to be used for drawing box around text.
+It is 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 box
+Used to draw a box around text using the background color.
+The value must be either 1 (enable) or 0 (disable).
+The default value of @var{box} is 0.
+
+@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. The default value for both is "0".
+
+@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
+The 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 tabsize
+The size in number of spaces to use for rendering the tab.
+Default value is 4.
+
+@item fix_bounds
+If true, check and fix text coords to avoid clipping.
+@end table
+
+For example the command:
+@example
+drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
+@end example
+
+will draw "Test Text" with font FreeSerif, using the default values
+for the optional parameters.
+
+The command:
+@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
+
+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%.
+
+Note that the double quotes are not necessary if spaces are not used
+within the parameter list.
+
+For more information about libfreetype, check:
+@url{http://www.freetype.org/}.
+
+@section fade
+
+Apply a fade-in/out effect to the input video.
+
+It accepts the following parameters:
+
+@table @option
+
+@item type
+The effect type can be either "in" for a fade-in, or "out" for a fade-out
+effect.
+
+@item start_frame
+The number of the frame to start applying the fade effect at.
+
+@item nb_frames
+The number of frames that the fade effect lasts. 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.
+
+@end table
+
+Some examples:
+@example
+# Fade in the first 30 frames of video
+fade=type=in:nb_frames=30
+
+# Fade out the last 45 frames of a 200-frame video
+fade=type=out:start_frame=155:nb_frames=45
+
+# Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video
+fade=type=in:start_frame=0:nb_frames=25, fade=type=out:start_frame=975:nb_frames=25
+
+# Make the first 5 frames black, then fade in from frame 5-24
+fade=type=in:start_frame=5:nb_frames=20
+@end example
+
+@section fieldorder
+
+Transform the field order of the input video.
+
+It accepts the following parameters:
+
+@table @option
+
+@item order
+The output field order. Valid values are @var{tff} for top field first or @var{bff}
+for bottom field first.
+@end table
+
+The default value is "tff".
+
+The transformation is done 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.
+
+It is very useful when converting to or from PAL DV material,
+which is bottom field first.
+
+For example:
+@example
+./avconv -i in.vob -vf "fieldorder=order=bff" out.dv
+@end example
+
+@section fifo
+
+Buffer input images and send them when they are requested.
+
+It is mainly useful when auto-inserted by the libavfilter
+framework.
+
+It does not take parameters.
+
+@section format
+
+Convert the input video to one of the specified pixel formats.
+Libavfilter will try to pick one that is suitable as input to
+the next filter.
+
+It accepts the following parameters:
+@table @option
+
+@item pix_fmts
+A '|'-separated list of pixel format names, such as
+"pix_fmts=yuv420p|monow|rgb24".
+
+@end table
+
+Some examples:
+@example
+# Convert the input video to the "yuv420p" format
+format=pix_fmts=yuv420p
+
+# Convert the input video to any of the formats in the list
+format=pix_fmts=yuv420p|yuv444p|yuv410p
+@end example
+
+@anchor{fps}
+@section fps
+
+Convert the video to specified constant framerate by duplicating or dropping
+frames as necessary.
+
+It accepts the following parameters:
+@table @option
+
+@item fps
+The desired output framerate.
+
+@item start_time
+Assume the first PTS should be the given value, in seconds. This allows for
+padding/trimming at the start of stream. By default, no assumption is made
+about the first frame's expected PTS, so no padding or trimming is done.
+For example, this could be set to 0 to pad the beginning with duplicates of
+the first frame if a video stream starts after the audio stream or to trim any
+frames with a negative PTS.
+
+@end table
+
+@section framepack
+
+Pack two different video streams into a stereoscopic video, setting proper
+metadata on supported codecs. The two views should have the same size and
+framerate and processing will stop when the shorter video ends. Please note
+that you may conveniently adjust view properties with the @ref{scale} and
+@ref{fps} filters.
+
+It accepts the following parameters:
+@table @option
+
+@item format
+The desired packing format. Supported values are:
+
+@table @option
+
+@item sbs
+The views are next to each other (default).
+
+@item tab
+The views are on top of each other.
+
+@item lines
+The views are packed by line.
+
+@item columns
+The views are packed by column.
+
+@item frameseq
+The views are temporally interleaved.
+
+@end table
+
+@end table
+
+Some examples:
+
+@example
+# Convert left and right views into a frame-sequential video
+avconv -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
+
+# Convert views into a side-by-side video with the same output resolution as the input
+avconv -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT
+@end example
+
+@anchor{frei0r}
+@section frei0r
+
+Apply a frei0r effect to the input video.
+
+To enable the compilation of this filter, you need to install the frei0r
+header and configure Libav with --enable-frei0r.
+
+It accepts the following parameters:
+
+@table @option
+
+@item filter_name
+The name of the frei0r effect to load. If the environment variable
+@env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the
+directories specified by the colon-separated list in @env{FREIOR_PATH}.
+Otherwise, the standard frei0r paths are searched, in this order:
+@file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
+@file{/usr/lib/frei0r-1/}.
+
+@item filter_params
+A '|'-separated list of parameters to pass to the frei0r effect.
+
+@end table
+
+A frei0r effect parameter can be a boolean (its value is either
+"y" or "n"), a double, a color (specified as
+@var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point
+numbers between 0.0 and 1.0, inclusive) or by an @code{av_parse_color()} color
+description), a position (specified as @var{X}/@var{Y}, where
+@var{X} and @var{Y} are floating point numbers) and/or a string.
+
+The number and types of parameters depend on the loaded effect. If an
+effect parameter is not specified, the default value is set.
+
+Some examples:
+@example
+# Apply the distort0r effect, setting the first two double parameters
+frei0r=filter_name=distort0r:filter_params=0.5|0.01
+
+# Apply the colordistance effect, taking a color as the first parameter
+frei0r=colordistance:0.2/0.3/0.4
+frei0r=colordistance:violet
+frei0r=colordistance:0x112233
+
+# Apply the perspective effect, specifying the top left and top right
+# image positions
+frei0r=perspective:0.2/0.2|0.8/0.2
+@end example
+
+For more information, see
+@url{http://piksel.org/frei0r}
+
+@section gradfun
+
+Fix the banding artifacts that are sometimes introduced into nearly flat
+regions by truncation to 8-bit colordepth.
+Interpolate the gradients that should go where the bands are, and
+dither them.
+
+It 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.
+
+It accepts the following parameters:
+
+@table @option
+
+@item strength
+The maximum amount by which the filter will change any one pixel. This is also
+the threshold for detecting nearly flat regions. Acceptable values range from
+.51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
+valid range.
+
+@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 8-32; the default value is 16. Out-of-range
+values will be clipped to the valid range.
+
+@end table
+
+@example
+# Default parameters
+gradfun=strength=1.2:radius=16
+
+# Omitting the radius
+gradfun=1.2
+@end example
+
+@section hflip
+
+Flip the input video horizontally.
+
+For example, to horizontally flip the input video with @command{avconv}:
+@example
+avconv -i in.avi -vf "hflip" out.avi
+@end example
+
+@section hqdn3d
+
+This is a high precision/quality 3d denoise filter. It aims to reduce
+image noise, producing smooth images and making still images really
+still. It should enhance compressibility.
+
+It accepts the following optional parameters:
+
+@table @option
+@item luma_spatial
+A non-negative floating point number which specifies spatial luma strength.
+It defaults to 4.0.
+
+@item chroma_spatial
+A non-negative floating point number which specifies spatial chroma strength.
+It defaults to 3.0*@var{luma_spatial}/4.0.
+
+@item luma_tmp
+A floating point number which specifies luma temporal strength. It defaults to
+6.0*@var{luma_spatial}/4.0.
+
+@item chroma_tmp
+A floating point number which specifies chroma temporal strength. It defaults to
+@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
+@end table
+
+@section hwupload_cuda
+
+Upload system memory frames to a CUDA device.
+
+It accepts the following optional parameters:
+
+@table @option
+@item device
+The number of the CUDA device to use
+@end table
+
+@section interlace
+
+Simple interlacing filter from progressive contents. This interleaves upper (or
+lower) lines from odd frames with lower (or upper) lines from even frames,
+halving the frame rate and preserving image height.
+
+@example
+ Original Original New Frame
+ Frame 'j' Frame 'j+1' (tff)
+ ========== =========== ==================
+ Line 0 --------------------> Frame 'j' Line 0
+ Line 1 Line 1 ----> Frame 'j+1' Line 1
+ Line 2 ---------------------> Frame 'j' Line 2
+ Line 3 Line 3 ----> Frame 'j+1' Line 3
+ ... ... ...
+New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
+@end example
+
+It accepts the following optional parameters:
+
+@table @option
+@item scan
+This determines whether the interlaced frame is taken from the even
+(tff - default) or odd (bff) lines of the progressive frame.
+
+@item lowpass
+Enable (default) or disable the vertical lowpass filter to avoid twitter
+interlacing and reduce moire patterns.
+@end table
+
+@section lut, lutrgb, lutyuv
+
+Compute a look-up table for binding each pixel component input value
+to an output value, and apply it to the input video.
+
+@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
+to an RGB input video.
+
+These filters accept the following parameters:
+@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)
+
+@item @var{r} (red component)
+@item @var{g} (green component)
+@item @var{b} (blue component)
+@item @var{a} (alpha component)
+
+@item @var{y} (Y/luminance component)
+@item @var{u} (U/Cb component)
+@item @var{v} (V/Cr component)
+@end table
+
+Each of them specifies the expression to use for computing the lookup table for
+the corresponding pixel component values.
+
+The exact component associated to each of the @var{c*} options depends on the
+format in input.
+
+The @var{lut} filter requires either YUV or RGB pixel formats in input,
+@var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
+
+The expressions can contain the following constants and functions:
+
+@table @option
+@item E, PI, PHI
+These are approximated values for the mathematical constants e
+(Euler's number), pi (Greek pi), and phi (the golden ratio).
+
+@item w, h
+The input width and height.
+
+@item val
+The input value for the pixel component.
+
+@item clipval
+The input value, clipped to the @var{minval}-@var{maxval} range.
+
+@item maxval
+The maximum value for the pixel component.
+
+@item minval
+The minimum value for the pixel component.
+
+@item negval
+The negated value for the pixel component value, clipped to the
+@var{minval}-@var{maxval} range; it corresponds to the expression
+"maxval-clipval+minval".
+
+@item clip(val)
+The computed value in @var{val}, clipped to the
+@var{minval}-@var{maxval} range.
+
+@item gammaval(gamma)
+The computed gamma correction value of the pixel component value,
+clipped to the @var{minval}-@var{maxval} range. It corresponds to the
+expression
+"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
+
+@end table
+
+All expressions default to "val".
+
+Some examples:
+@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, turning the video into a graytone image
+lutyuv="u=128:v=128"
+
+# Apply a luma burning effect
+lutyuv="y=2*val"
+
+# Remove green and blue components
+lutrgb="g=0:b=0"
+
+# Set a constant alpha channel value on input
+format=rgba,lutrgb=a="maxval-minval/2"
+
+# Correct luminance gamma by a factor of 0.5
+lutyuv=y=gammaval(0.5)
+@end example
+
+@section negate
+
+Negate input video.
+
+It 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.
+
+It accepts the following parameters:
+@table @option
+
+@item pix_fmts
+A '|'-separated list of pixel format names, such as
+apix_fmts=yuv420p|monow|rgb24".
+
+@end table
+
+Some examples:
+@example
+# Force libavfilter to use a format different from "yuv420p" for the
+# input to the vflip filter
+noformat=pix_fmts=yuv420p,vflip
+
+# Convert the input video to any of the formats not contained in the list
+noformat=yuv420p|yuv444p|yuv410p
+@end example
+
+@section null
+
+Pass the video source unchanged to the output.
+
+@section ocv
+
+Apply a video transform using libopencv.
+
+To enable this filter, install the libopencv library and headers and
+configure Libav with --enable-libopencv.
+
+It accepts the following parameters:
+
+@table @option
+
+@item filter_name
+The name of the libopencv filter to apply.
+
+@item filter_params
+The parameters to pass to the libopencv filter. If not specified, the default
+values are assumed.
+
+@end table
+
+Refer to the official libopencv documentation for more precise
+information:
+@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
+
+Several libopencv filters are supported; see the following subsections.
+
+@anchor{dilate}
+@subsection dilate
+
+Dilate an image by using a specific structuring element.
+It 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. @var{shape}
+must be "rect", "cross", "ellipse", or "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.
+
+Some examples:
+@example
+# Use the default values
+ocv=dilate
+
+# Dilate using a structuring element with a 5x5 cross, iterating two times
+ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
+
+# Read the shape from the file diamond.shape, iterating two times.
+# The file diamond.shape may contain a pattern of characters like this
+# *
+# ***
+# *****
+# ***
+# *
+# The specified columns and rows are ignored
+# but the anchor point coordinates are not
+ocv=dilate:0x0+2x2/custom=diamond.shape|2
+@end example
+
+@subsection erode
+
+Erode an image by using a specific structuring element.
+It corresponds to the libopencv function @code{cvErode}.
+
+It 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 must be one of
+the following values: "blur", "blur_no_scale", "median", "gaussian",
+or "bilateral". The default value is "gaussian".
+
+The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4}
+depend on the smooth type. @var{param1} and
+@var{param2} accept integer positive values or 0. @var{param3} and
+@var{param4} accept floating point 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 has one output. The first input is the "main"
+video on which the second input is overlaid.
+
+It accepts the following parameters:
+
+@table @option
+
+@item x
+The horizontal position of the left edge of the overlaid video on the main video.
+
+@item y
+The vertical position of the top edge of the overlaid video on the main video.
+
+@end table
+
+The parameters are expressions containing the following parameters:
+
+@table @option
+@item main_w, main_h
+The main input width and height.
+
+@item W, H
+These are the same as @var{main_w} and @var{main_h}.
+
+@item overlay_w, overlay_h
+The overlay input width and height.
+
+@item w, h
+These are the same as @var{overlay_w} and @var{overlay_h}.
+
+@item eof_action
+The action to take when EOF is encountered on the secondary input; it accepts
+one of the following values:
+
+@table @option
+@item repeat
+Repeat the last frame (the default).
+@item endall
+End both streams.
+@item pass
+Pass the main input through.
+@end table
+
+@end table
+
+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 the example for
+the @var{movie} filter does.
+
+Some examples:
+@example
+# Draw the overlay at 10 pixels from the bottom right
+# corner of the main video
+overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
+
+# Insert a transparent PNG logo in the bottom left corner of the input
+avconv -i input -i logo -filter_complex 'overlay=x=10:y=main_h-overlay_h-10' output
+
+# Insert 2 different transparent PNG logos (second logo on bottom
+# right corner)
+avconv -i input -i logo1 -i logo2 -filter_complex
+'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
+
+# 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]
+
+# Mask 10-20 seconds of a video by applying the delogo filter to a section
+avconv -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
+-vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
+masked.avi
+@end example
+
+You can chain together more overlays but the efficiency of such
+approach is yet to be tested.
+
+@section pad
+
+Add paddings to the input image, and place the original input at the
+provided @var{x}, @var{y} coordinates.
+
+It accepts the following parameters:
+
+@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.
+
+The default value of @var{width} and @var{height} is 0.
+
+@item x, y
+
+Specify the offsets to place the input image at within 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 an 0xRRGGBB[AA] sequence.
+
+The default value of @var{color} is "black".
+
+@end table
+
+The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
+expressions containing the following constants:
+
+@table @option
+@item E, PI, PHI
+These are approximated values for the mathematical constants e
+(Euler's number), pi (Greek pi), and phi (the golden ratio).
+
+@item in_w, in_h
+The input video width and height.
+
+@item iw, ih
+These are the same as @var{in_w} and @var{in_h}.
+
+@item out_w, out_h
+The output width and height (the size of the padded area), as
+specified by the @var{width} and @var{height} expressions.
+
+@item ow, oh
+These are the same as @var{out_w} and @var{out_h}.
+
+@item x, y
+The x and y offsets as specified by the @var{x} and @var{y}
+expressions, or NAN if not yet specified.
+
+@item a
+The input display aspect ratio, same as @var{iw} / @var{ih}.
+
+@item hsub, vsub
+The horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+@end table
+
+Some examples:
+
+@example
+# Add paddings with the color "violet" to the input video. The output video
+# size is 640x480, and the top-left corner of the input video is placed at
+# column 0, row 40
+pad=width=640:height=480:x=0:y=40:color=violet
+
+# 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
+pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
+
+# 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"
+
+# Pad the input to get a final w/h ratio of 16:9
+pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
+
+# Double the 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 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.
+
+@anchor{scale}
+@section scale
+
+Scale the input video and/or convert the image format.
+
+It accepts the following parameters:
+
+@table @option
+
+@item w
+The output video width.
+
+@item h
+The output video height.
+
+@end table
+
+The parameters @var{w} and @var{h} are expressions containing
+the following constants:
+
+@table @option
+@item E, PI, PHI
+These are approximated values for the mathematical constants e
+(Euler's number), pi (Greek pi), and phi (the golden ratio).
+
+@item in_w, in_h
+The input width and height.
+
+@item iw, ih
+These are the same as @var{in_w} and @var{in_h}.
+
+@item out_w, out_h
+The output (cropped) width and height.
+
+@item ow, oh
+These are the same as @var{out_w} and @var{out_h}.
+
+@item a
+This is the same as @var{iw} / @var{ih}.
+
+@item sar
+input sample aspect ratio
+
+@item dar
+The input display aspect ratio; it is the same as
+(@var{iw} / @var{ih}) * @var{sar}.
+
+@item hsub, vsub
+The 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{w} or @var{h} is 0, the respective input
+size is used for the output.
+
+If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
+respective output size, a value that maintains the aspect ratio of the input
+image.
+
+The default value of @var{w} and @var{h} is 0.
+
+Some examples:
+@example
+# Scale the input video to a size of 200x100
+scale=w=200:h=100
+
+# Scale the input to 2x
+scale=w=2*iw:h=2*ih
+# The above is the same as
+scale=2*in_w:2*in_h
+
+# Scale the input to half the original size
+scale=w=iw/2:h=ih/2
+
+# Increase the width, and set the height to the same size
+scale=3/2*iw:ow
+
+# Seek Greek harmony
+scale=iw:1/PHI*iw
+scale=ih*PHI:ih
+
+# Increase the height, and set the width to 3/2 of the height
+scale=w=3/2*oh:h=3/5*ih
+
+# Increase the size, making the size a multiple of the chroma
+scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
+
+# Increase the width to a maximum of 500 pixels,
+# keeping the same aspect ratio as the input
+scale=w='min(500\, iw*3/2):h=-1'
+@end example
+
+@section scale_npp
+
+Use the NVIDIA Performance Primitives (libnpp) to perform scaling and/or pixel
+format conversion on CUDA video frames. Setting the output width and height
+works in the same way as for the @var{scale} filter.
+
+The following additional options are accepted:
+@table @option
+@item format
+The pixel format of the output CUDA frames. If set to the string "same" (the
+default), the input format will be kept. Note that automatic format negotiation
+and conversion is not yet supported for hardware frames
+
+@item interp_algo
+The interpolation algorithm used for resizing. One of the following:
+@table @option
+@item nn
+Nearest neighbour.
+
+@item linear
+@item cubic
+@item cubic2p_bspline
+2-parameter cubic (B=1, C=0)
+
+@item cubic2p_catmullrom
+2-parameter cubic (B=0, C=1/2)
+
+@item cubic2p_b05c03
+2-parameter cubic (B=1/2, C=3/10)
+
+@item super
+Supersampling
+
+@item lanczos
+@end table
+
+@end table
+
+@section select
+Select frames to pass in output.
+
+It accepts the following parameters:
+
+@table @option
+
+@item expr
+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.
+
+@end table
+
+The expression can contain the following constants:
+
+@table @option
+@item E, PI, PHI
+These are approximated values for the mathematical constants e
+(Euler's number), pi (Greek pi), and phi (the golden ratio).
+
+@item n
+The (sequential) number of the filtered frame, starting from 0.
+
+@item selected_n
+The (sequential) number of the selected frame, starting from 0.
+
+@item prev_selected_n
+The sequential number of the last selected frame. It's NAN if undefined.
+
+@item TB
+The timebase of the input timestamps.
+
+@item pts
+The PTS (Presentation TimeStamp) of the filtered video frame,
+expressed in @var{TB} units. It's NAN if undefined.
+
+@item t
+The PTS of the filtered video frame,
+expressed in seconds. It's NAN if undefined.
+
+@item prev_pts
+The PTS of the previously filtered video frame. It's NAN if undefined.
+
+@item prev_selected_pts
+The PTS of the last previously filtered video frame. It's NAN if undefined.
+
+@item prev_selected_t
+The PTS of the last previously selected video frame. It's NAN if undefined.
+
+@item start_pts
+The PTS of the first video frame in the video. It's NAN if undefined.
+
+@item start_t
+The time of the first video frame in the video. It's NAN if undefined.
+
+@item pict_type
+The type of the filtered frame. It can assume one of the following
+values:
+@table @option
+@item I
+@item P
+@item B
+@item S
+@item SI
+@item SP
+@item BI
+@end table
+
+@item interlace_type
+The frame interlace type. It can assume one of the following values:
+@table @option
+@item PROGRESSIVE
+The frame is progressive (not interlaced).
+@item TOPFIRST
+The frame is top-field-first.
+@item BOTTOMFIRST
+The frame is bottom-field-first.
+@end table
+
+@item key
+This is 1 if the filtered frame is a key-frame, 0 otherwise.
+
+@end table
+
+The default value of the select expression is "1".
+
+Some examples:
+
+@example
+# Select all the frames in input
+select
+
+# The above is the same as
+select=expr=1
+
+# Skip all frames
+select=expr=0
+
+# Select only I-frames
+select='expr=eq(pict_type\,I)'
+
+# Select one frame per 100
+select='not(mod(n\,100))'
+
+# Select only frames contained in the 10-20 time interval
+select='gte(t\,10)*lte(t\,20)'
+
+# Select only I-frames contained in the 10-20 time interval
+select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
+
+# Select frames with a minimum distance of 10 seconds
+select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
+@end example
+
+@anchor{setdar}
+@section setdar
+
+Set 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:
+@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
+
+Keep in mind that this 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.
+
+It accepts the following parameters:
+
+@table @option
+
+@item dar
+The output display aspect ratio.
+
+@end table
+
+The parameter @var{dar} is an expression containing
+the following constants:
+
+@table @option
+@item E, PI, PHI
+These are approximated values for the mathematical constants e
+(Euler's number), pi (Greek pi), and phi (the golden ratio).
+
+@item w, h
+The input width and height.
+
+@item a
+This is the same as @var{w} / @var{h}.
-Force libavfilter not to use any of the specified pixel formats for the
-input to the next filter.
+@item sar
+The input sample aspect ratio.
-The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
+@item dar
+The input display aspect ratio. It is the same as
+(@var{w} / @var{h}) * @var{sar}.
-The following command:
+@item hsub, vsub
+The horizontal and vertical chroma subsample values. For example, for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+@end table
+To change the display aspect ratio to 16:9, specify:
@example
-./ffmpeg -i in.avi -vf "noformat=yuv420p, vflip" out.avi
+setdar=dar=16/9
+# The above is equivalent to
+setdar=dar=1.77777
@end example
-will make libavfilter use a format different from "yuv420p" for the
-input to the vflip filter.
-
-@section null
+Also see the the @ref{setsar} filter documentation.
-Pass the video source unchanged to the output.
+@section setpts
-@section ocv_smooth
+Change the PTS (presentation timestamp) of the input video frames.
-Apply smooth transform using libopencv.
+It accepts the following parameters:
-To enable this filter install libopencv library and headers and
-configure FFmpeg with --enable-libopencv.
+@table @option
-The filter accepts the following parameters:
-@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
+@item expr
+The expression which is evaluated for each frame to construct its timestamp.
-@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".
+@end table
-@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 expression is evaluated through the eval API and can contain the following
+constants:
-The default value for @var{param1} is 3, the default value for the
-other parameters is 0.
+@table @option
+@item PTS
+The presentation timestamp in input.
-These parameters correspond to the parameters assigned to the
-libopencv function @code{cvSmooth}. Refer to the official libopencv
-documentation for the exact meaning of the parameters:
-@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
+@item E, PI, PHI
+These are approximated values for the mathematical constants e
+(Euler's number), pi (Greek pi), and phi (the golden ratio).
-@section overlay
+@item N
+The count of the input frame, starting from 0.
-Overlay one video on top of another.
+@item STARTPTS
+The PTS of the first video frame.
-It takes two inputs and one output, the first input is the "main"
-video on which the second input is overlayed.
+@item INTERLACED
+State whether the current frame is interlaced.
-It accepts the parameters: @var{x}:@var{y}.
+@item PREV_INPTS
+The previous input PTS.
-@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:
+@item PREV_OUTPTS
+The previous output PTS.
-@table @option
-@item main_w, main_h
-main input width and height
+@item RTCTIME
+The wallclock (RTC) time in microseconds.
-@item W, H
-same as @var{main_w} and @var{main_h}
+@item RTCSTART
+The wallclock (RTC) time at the start of the movie in microseconds.
-@item overlay_w, overlay_h
-overlay input width and height
+@item TB
+The timebase of the input timestamps.
-@item w, h
-same as @var{overlay_w} and @var{overlay_h}
@end table
-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.
+Some examples:
-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
+# Start counting the PTS from zero
+setpts=expr=PTS-STARTPTS
+
+# Fast motion
+setpts=expr=0.5*PTS
-# insert a transparent PNG logo in the bottom left corner of the input
-movie=0:png:logo.png [logo];
-[in][logo] overlay=10:main_h-overlay_h-10 [out]
+# Slow motion
+setpts=2.0*PTS
-# insert 2 different transparent PNG logos (second logo on bottom
-# right corner):
-movie=0:png:logo1.png [logo1];
-movie=0:png:logo2.png [logo2];
-[in][logo1] overlay=10:H-h-10 [in+logo1];
-[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
+# Fixed rate 25 fps
+setpts=N/(25*TB)
-# 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]
+# Fixed rate 25 fps with some jitter
+setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
+
+# Generate timestamps from a "live source" and rebase onto the current timebase
+setpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
@end example
-You can chain togheter more overlays but the efficiency of such
-approach is yet to be tested.
+@anchor{setsar}
+@section setsar
-@section pad
+Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
-Add paddings to the input image, and places the original input at the
-given coordinates @var{x}, @var{y}.
+Note that as a consequence of the application of this filter, the
+output display aspect ratio will change according to the following
+equation:
+@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
-It accepts the following parameters:
-@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
+Keep in mind that the sample aspect ratio set by this filter may be
+changed by later filters in the filterchain, e.g. if another "setsar"
+or a "setdar" filter is applied.
-Follows the description of the accepted parameters.
+It accepts the following parameters:
@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.
+@item sar
+The output sample aspect ratio.
-The default value of @var{width} and @var{height} is 0.
+@end table
-@item x, y
+The parameter @var{sar} is an expression containing
+the following constants:
-Specify the offsets where to place the input image in the padded area
-with respect to the top/left border of the output image.
+@table @option
+@item E, PI, PHI
+These are approximated values for the mathematical constants e
+(Euler's number), pi (Greek pi), and phi (the golden ratio).
-The default value of @var{x} and @var{y} is 0.
+@item w, h
+The input width and height.
-@item color
+@item a
+These are the same as @var{w} / @var{h}.
-Specify the color of the padded area, it can be the name of a color
-(case insensitive match) or a 0xRRGGBB[AA] sequence.
+@item sar
+The input sample aspect ratio.
-The default value of @var{color} is "black".
+@item dar
+The 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.
@end table
-For example:
-
+To change the sample aspect ratio to 10:11, specify:
@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
-# row 0, column 40.
-pad=640:480:0:40:violet
+setsar=sar=10/11
@end example
-@section pixdesctest
+@section settb
-Pixel format descriptor test filter, mainly useful for internal
-testing. The output video should be equal to the input video.
+Set the timebase to use for the output frames timestamps.
+It is mainly useful for testing timebase configuration.
-For example:
-@example
-format=monow, pixdesctest
-@end example
+It accepts the following parameters:
-can be used to test the monowhite pixel format descriptor definition.
+@table @option
-@section scale
+@item expr
+The expression which is evaluated into the output timebase.
-Scale the input video to @var{width}:@var{height} and/or convert the image format.
+@end table
-For example the command:
+The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
+default timebase), and "intb" (the input timebase).
+
+The default value for the input is "intb".
+
+Some examples:
@example
-./ffmpeg -i in.avi -vf "scale=200:100" out.avi
-@end example
+# Set the timebase to 1/25
+settb=expr=1/25
-will scale the input video to a size of 200x100.
+# Set the timebase to 1/10
+settb=expr=0.1
-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.
+# Set the timebase to 1001/1000
+settb=1+0.001
-If the value for @var{width} or @var{height} is 0, the respective input
-size is used for the output.
+#Set the timebase to 2*intb
+settb=2*intb
-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.
+#Set the default timebase value
+settb=AVTB
+@end example
-The default value of @var{width} and @var{height} is 0.
+@section showinfo
-@section setpts
+Show a line containing various information for each input video frame.
+The input video is not modified.
-Change the PTS (presentation timestamp) of the input video frames.
+The shown line contains a sequence of key/value pairs of the form
+@var{key}:@var{value}.
-Accept in input an expression evaluated through the eval API, which
-can contain the following constants:
+It accepts the following parameters:
@table @option
-@item PTS
-the presentation timestamp in input
+@item n
+The (sequential) number of the input frame, starting from 0.
-@item PI
-Greek PI
+@item pts
+The 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 PHI
-golden ratio
+@item pts_time
+The Presentation TimeStamp of the input frame, expressed as a number of
+seconds.
-@item E
-Euler number
+@item pos
+The position of the frame in the input stream, or -1 if this information is
+unavailable and/or meaningless (for example in case of synthetic video).
-@item N
-the count of the input frame, starting from 0.
+@item fmt
+The pixel format name.
-@item STARTPTS
-the PTS of the first video frame
+@item sar
+The sample aspect ratio of the input frame, expressed in the form
+@var{num}/@var{den}.
-@item INTERLACED
-tell if the current frame is interlaced
+@item s
+The size of the input frame, expressed in the form
+@var{width}x@var{height}.
-@item POS
-original position in the file of the frame, or undefined if undefined
-for the current frame
+@item i
+The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
+for bottom field first).
-@item PREV_INPTS
-previous input PTS
+@item iskey
+This is 1 if the frame is a key frame, 0 otherwise.
-@item PREV_OUTPTS
-previous output PTS
+@item type
+The picture type of the input frame ("I" for an I-frame, "P" for a
+P-frame, "B" for a B-frame, or "?" for an unknown type).
+Also refer to the documentation of the @code{AVPictureType} enum and of
+the @code{av_get_picture_type_char} function defined in
+@file{libavutil/avutil.h}.
-@end table
+@item checksum
+The Adler-32 checksum of all the planes of the input frame.
-Some examples follow:
+@item plane_checksum
+The Adler-32 checksum of each plane of the input frame, expressed in the form
+"[@var{c0} @var{c1} @var{c2} @var{c3}]".
+@end table
-@example
-# start counting PTS from zero
-setpts=PTS-STARTPTS
+@section shuffleplanes
-# fast motion
-setpts=0.5*PTS
+Reorder and/or duplicate video planes.
-# slow motion
-setpts=2.0*PTS
+It accepts the following parameters:
-# fixed rate 25 fps
-setpts=N/(25*TB)
+@table @option
-# fixed rate 25 fps with some jitter
-setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
-@end example
+@item map0
+The index of the input plane to be used as the first output plane.
-@section settb
+@item map1
+The index of the input plane to be used as the second output plane.
-Set the timebase to use for the output frames timestamps.
-It is mainly useful for testing timebase configuration.
+@item map2
+The index of the input plane to be used as the third output plane.
-It accepts in input an arithmetic expression representing a rational.
-The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
-default timebase), and "intb" (the input timebase).
+@item map3
+The index of the input plane to be used as the fourth output plane.
-The default value for the input is "intb".
+@end table
-Follow some examples.
+The first plane has the index 0. The default is to keep the input unchanged.
+Swap the second and third planes of the input:
@example
-# set the timebase to 1/25
-settb=1/25
+avconv -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
+@end example
-# set the timebase to 1/10
-settb=0.1
+@section split
-#set the timebase to 1001/1000
-settb=1+0.001
+Split input video into several identical outputs.
-#set the timebase to 2*intb
-settb=2*intb
+It accepts a single parameter, which specifies the number of outputs. If
+unspecified, it defaults to 2.
-#set the default timebase value
-settb=AVTB
+Create 5 copies of the input video:
+@example
+avconv -i INPUT -filter_complex split=5 OUTPUT
@end example
-@section slicify
-
-Pass the images of input video on to next video filter as multiple
-slices.
+@section transpose
-@example
-./ffmpeg -i in.avi -vf "slicify=32" out.avi
-@end example
+Transpose rows with columns in the input video and optionally flip it.
-The filter accepts the slice height as parameter. If the parameter is
-not specified it will use the default value of 16.
+It accepts the following parameters:
-Adding this in the beginning of filter chains should make filtering
-faster due to better use of the memory cache.
+@table @option
-@section transpose
+@item dir
+The direction of the transpose.
-Transpose rows with columns in the input video and optionally flip it.
+@end table
-It accepts a parameter representing an integer, which can assume the
-values:
+The direction can assume the following values:
@table @samp
-@item 0
+@item cclock_flip
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
@example
L.R L.l
l.r R.r
@end example
-@item 1
+@item clock
Rotate by 90 degrees clockwise, that is:
@example
L.R l.L
l.r r.R
@end example
-@item 2
+@item cclock
Rotate by 90 degrees counterclockwise, that is:
@example
L.R R.r
l.r L.l
@end example
-@item 3
+@item clock_flip
Rotate by 90 degrees clockwise and vertically flip, that is:
@example
L.R r.R
@end example
@end table
+@section trim
+Trim the input so that the output contains one continuous subpart of the input.
+
+It accepts the following parameters:
+@table @option
+@item start
+The timestamp (in seconds) of the start of the kept section. The frame with the
+timestamp @var{start} will be the first frame in the output.
+
+@item end
+The timestamp (in seconds) of the first frame that will be dropped. The frame
+immediately preceding the one with the timestamp @var{end} will be the last
+frame in the output.
+
+@item start_pts
+This is the same as @var{start}, except this option sets the start timestamp
+in timebase units instead of seconds.
+
+@item end_pts
+This is the same as @var{end}, except this option sets the end timestamp
+in timebase units instead of seconds.
+
+@item duration
+The maximum duration of the output in seconds.
+
+@item start_frame
+The number of the first frame that should be passed to the output.
+
+@item end_frame
+The number of the first frame that should be dropped.
+@end table
+
+Note that the first two sets of the start/end options and the @option{duration}
+option look at the frame timestamp, while the _frame variants simply count the
+frames that pass through the filter. Also note that this filter does not modify
+the timestamps. If you wish for the output timestamps to start at zero, insert a
+setpts filter after the trim filter.
+
+If multiple start or end options are set, this filter tries to be greedy and
+keep all the frames that match at least one of the specified constraints. To keep
+only the part that matches all the constraints at once, chain multiple trim
+filters.
+
+The defaults are such that all the input is kept. So it is possible to set e.g.
+just the end values to keep everything before the specified time.
+
+Examples:
+@itemize
+@item
+Drop everything except the second minute of input:
+@example
+avconv -i INPUT -vf trim=60:120
+@end example
+
+@item
+Keep only the first second:
+@example
+avconv -i INPUT -vf trim=duration=1
+@end example
+
+@end itemize
@section unsharp
Sharpen or blur the input video.
It accepts the following parameters:
-@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
-
-Negative values for the amount will blur the input video, while positive
-values will sharpen. All parameters are optional and default to the
-equivalent of the string '5:5:1.0:0:0:0.0'.
@table @option
@item luma_msize_x
-Set the luma matrix horizontal size. It can be an integer between 3
-and 13, default value is 5.
+Set the luma matrix horizontal size. It must be an integer between 3
+and 13. The default value is 5.
@item luma_msize_y
-Set the luma matrix vertical size. It can be an integer between 3
-and 13, default value is 5.
+Set the luma matrix vertical size. It must be an integer between 3
+and 13. The default value is 5.
@item luma_amount
-Set the luma effect strength. It can be a float number between -2.0
-and 5.0, default value is 1.0.
+Set the luma effect strength. It must be a floating point number between -2.0
+and 5.0. The default value is 1.0.
@item chroma_msize_x
-Set the chroma matrix horizontal size. It can be an integer between 3
-and 13, default value is 0.
+Set the chroma matrix horizontal size. It must be an integer between 3
+and 13. The default value is 5.
@item chroma_msize_y
-Set the chroma matrix vertical size. It can be an integer between 3
-and 13, default value is 0.
+Set the chroma matrix vertical size. It must be an integer between 3
+and 13. The default value is 5.
-@item luma_amount
-Set the chroma effect strength. It can be a float number between -2.0
-and 5.0, default value is 0.0.
+@item chroma_amount
+Set the chroma effect strength. It must be a floating point number between -2.0
+and 5.0. The default value is 0.0.
@end table
+Negative values for the amount will blur the input video, while positive
+values will sharpen. All parameters are optional and default to the
+equivalent of the string '5:5:1.0:5:5:0.0'.
+
@example
# Strong luma sharpen effect parameters
-unsharp=7:7:2.5
+unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
-# Strong blur of both luma and chroma parameters
+# A strong blur of both luma and chroma parameters
unsharp=7:7:-2:7:7:-2
-# Use the default values with @command{ffmpeg}
-./ffmpeg -i in.avi -vf "unsharp" out.mp4
+# Use the default values with @command{avconv}
+./avconv -i in.avi -vf "unsharp" out.mp4
@end example
@section vflip
Flip the input video vertically.
@example
-./ffmpeg -i in.avi -vf "vflip" out.avi
+./avconv -i in.avi -vf "vflip" out.avi
@end example
@section yadif
-yadif is "yet another deinterlacing filter".
+Deinterlace the input video ("yadif" means "yet another deinterlacing
+filter").
-It accepts the syntax:
-@example
-yadif=[@var{mode}[:@var{parity}]]
-@end example
+It accepts the following parameters:
@table @option
@item mode
-Specify the interlacing mode to adopt, accepts one of the following values.
+The interlacing mode to adopt. It accepts one of the following values:
+
+@table @option
+@item 0
+Output one frame for each frame.
+@item 1
+Output one frame for each field.
+@item 2
+Like 0, but it skips the spatial interlacing check.
+@item 3
+Like 1, but it skips the spatial interlacing check.
+@end table
-0: Output 1 frame for each frame.
+The default value is 0.
-1: Output 1 frame for each field.
+@item parity
+The picture field parity assumed for the input interlaced video. It accepts one
+of the following values:
-2: Like 0 but skips spatial interlacing check.
+@table @option
+@item 0
+Assume the top field is first.
+@item 1
+Assume the bottom field is first.
+@item -1
+Enable automatic detection of field parity.
+@end table
-3: Like 1 but skips spatial interlacing check.
+The default value is -1.
+If the interlacing is unknown or the decoder does not export this information,
+top field first will be assumed.
-Default value is 0.
+@item auto
+Whether the deinterlacer should trust the interlaced flag and only deinterlace
+frames marked as interlaced.
-@item parity
-0 if is bottom field first, 1 if the interlaced video is top field
-first, -1 to enable automatic detection.
+@table @option
+@item 0
+Deinterlace all frames.
+@item 1
+Only deinterlace frames marked as interlaced.
+@end table
+
+The default value is 0.
@end table
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
It accepts the following parameters:
-@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}
-All the parameters need to be explicitely defined.
+@table @option
-Follows the list of the accepted parameters.
+@item width
+The input video width.
-@table @option
+@item height
+The input video height.
-@item width, height
-Specify the width and height of the buffered video frames.
+@item pix_fmt
+The name of the input video pixel format.
-@item pix_fmt_string
-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.
+@item time_base
+The time base used for input timestamps.
+
+@item sar
+The sample (pixel) aspect ratio of the input video.
+
+@item hw_frames_ctx
+When using a hardware pixel format, this should be a reference to an
+AVHWFramesContext describing input frames.
-@item timebase_num, timebase_den
-Specify numerator and denomitor of the timebase assumed by the
-timestamps of the buffered frames.
@end table
For example:
@example
-buffer=320:240:yuv410p:1:24
+buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
@end example
will instruct the source to accept video frames with size 320x240 and
-with format "yuv410p" and assuming 1/24 as the timestamps timebase.
-Since the pixel format with name "yuv410p" corresponds to the number 6
-(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
-this example corresponds to:
-@example
-buffer=320:240:6:1:24
-@end example
+with format "yuv410p", assuming 1/24 as the timestamps timebase and
+square pixels (1:1 sample aspect ratio).
@section color
Provide an uniformly colored input.
It accepts the following parameters:
-@var{color}:@var{frame_size}:@var{frame_rate}
-
-Follows the description of the accepted parameters.
@table @option
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
alpha specifier. The default value is "black".
-@item frame_size
+@item size
Specify the size of the sourced video, it may be a string of the form
-@var{width}x@var{heigth}, or the name of a size abbreviation. The
+@var{width}x@var{height}, or the name of a size abbreviation. The
default value is "320x240".
-@item frame_rate
+@item framerate
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
+@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
number or a valid video frame rate abbreviation. The default value is
"25".
@end table
-For example the following graph description will generate a red source
+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, which will be overlayed over the source connected
-to the pad with identifier "in".
+frames per second, which will be overlaid over the source connected
+to the pad with identifier "in":
@example
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
@end example
+@section movie
+
+Read a video stream from a movie container.
+
+Note that this source is a hack that bypasses the standard input path. It can be
+useful in applications that do not support arbitrary filter graphs, but its use
+is discouraged in those that do. It should never be used with
+@command{avconv}; the @option{-filter_complex} option fully replaces it.
+
+It accepts the following parameters:
+
+@table @option
+
+@item filename
+The name of the resource to read (not necessarily a file; it can also be a
+device or a stream accessed through some protocol).
+
+@item format_name, f
+Specifies the format assumed for the movie to read, and can be either
+the name of a container or an input device. If not specified, the
+format is guessed from @var{movie_name} or by probing.
+
+@item seek_point, sp
+Specifies the seek point in seconds. The frames will be output
+starting from this seek point. The parameter is evaluated with
+@code{av_strtod}, so the numerical value may be suffixed by an IS
+postfix. The default value is "0".
+
+@item stream_index, si
+Specifies the index of the video stream to read. If the value is -1,
+the most suitable video stream will be automatically selected. The default
+value is "-1".
+
+@end table
+
+It allows overlaying a second video on top of the main input of
+a filtergraph, as shown in this graph:
+@example
+input -----------> deltapts0 --> overlay --> output
+ ^
+ |
+movie --> scale--> deltapts1 -------+
+@end example
+
+Some examples:
+@example
+# Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
+# on top of the input labelled "in"
+movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
+[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
+
+# Read from a video4linux2 device, and overlay it on top of the input
+# labelled "in"
+movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
+[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
+
+@end example
+
@section nullsrc
-Null video source, never return images. It is mainly useful as a
+Null video source: never return images. It is mainly useful as a
template and to be employed in analysis / debugging tools.
-It accepts as optional parameter a string of the form
-@var{width}:@var{height}:@var{timebase}.
+It accepts a string of the form
+@var{width}:@var{height}:@var{timebase} as an optional parameter.
@var{width} and @var{height} specify the size of the configured
source. The default values of @var{width} and @var{height} are
respectively 352 and 288 (corresponding to the CIF size format).
@var{timebase} specifies an arithmetic expression representing a
-timebase. The expression can contain the constants "PI", "E", "PHI",
+timebase. The expression can contain the constants "PI", "E", "PHI", and
"AVTB" (the default timebase), and defaults to the value "AVTB".
@section frei0r_src
Provide a frei0r source.
To enable compilation of this filter you need to install the frei0r
-header and configure FFmpeg with --enable-frei0r.
+header and configure Libav with --enable-frei0r.
+
+This source accepts the following parameters:
+
+@table @option
+
+@item size
+The size of the video to generate. It may be a string of the form
+@var{width}x@var{height} or a frame size abbreviation.
+
+@item framerate
+The framerate of the generated video. It may be a string of the form
+@var{num}/@var{den} or a frame rate abbreviation.
+
+@item filter_name
+The name to the frei0r source to load. For more information regarding frei0r and
+how to set the parameters, read the @ref{frei0r} section in the video filters
+documentation.
-The source supports the syntax:
+@item filter_params
+A '|'-separated list of parameters to pass to the frei0r source.
+
+@end table
+
+An example:
@example
-@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
+# Generate a frei0r partik0l source with size 200x200 and framerate 10
+# which is overlaid on the overlay filter's main input
+frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
@end example
-@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 "frei0r" (@pxref{frei0r}) in the description of the video
-filters.
+@section rgbtestsrc, testsrc
+
+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.
+
+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.
+
+The sources accept the following parameters:
+
+@table @option
+
+@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".
-Some examples follow:
+@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 floating point
+number or a valid video frame rate abbreviation. The default value is
+"25".
+
+@item sar
+Set the sample aspect ratio of the sourced video.
+
+@item duration
+Set the video duration of the sourced video. The accepted syntax is:
+@example
+[-]HH[:MM[:SS[.m...]]]
+[-]S+[.m...]
+@end example
+Also see the the @code{av_parse_time()} function.
+
+If not specified, or the expressed duration is negative, the video is
+supposed to be generated forever.
+@end table
+
+For example the following:
@example
-# generate a frei0r partik0l source with size 200x200 and framerate 10
-# which is overlayed on the overlay filter main input
-frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
+testsrc=duration=5.3:size=qcif:rate=10
@end example
+will generate a video with a duration of 5.3 seconds, with size
+176x144 and a framerate of 10 frames per second.
+
@c man end VIDEO SOURCES
@chapter Video Sinks
Below is a description of the currently available video sinks.
+@section buffersink
+
+Buffer video frames, and make them available to the end of the filter
+graph.
+
+This sink is intended for programmatic use through the interface defined in
+@file{libavfilter/buffersink.h}.
+
@section nullsink
-Null video sink, do absolutely nothing with the input video. It is
-mainly useful as a template and to be employed in analysis / debugging
+Null video sink: do absolutely nothing with the input video. It is
+mainly useful as a template and for use in analysis / debugging
tools.
@c man end VIDEO SINKS
-
projects / ffmpeg / blobdiff