The parameters are expressions containing the following constants:
@table @option
-@item E, PI, PHI
-the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), PHI (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 heigth
+the input width and height
@item iw, ih
same as @var{in_w} and @var{in_h}
@item out_w, out_h
-the output (cropped) width and heigth
+the output (cropped) width and height
@item ow, oh
same as @var{out_w} and @var{out_h}
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.
-Relative to the top/left border of the output image.
+The expressions which specify the offsets where text will be drawn
+within the video frame. They are relative to the top/left border of the
+output image.
-The default value of @var{x} and @var{y} is 0.
+The default value of @var{x} and @var{y} is "0".
+
+See below for the list of accepted constants.
@item fontsize
The font size to be used for drawing text.
Default value is 4.
@end table
-For example the command:
+The parameters for @var{x} and @var{y} are expressions containing the
+following constants:
+
+@table @option
+@item w, h
+the input width and heigth
+
+@item tw, text_w
+the width of the rendered text
+
+@item th, text_h
+the height of the rendered text
+
+@item lh, line_h
+the height of each text line
+
+@item sar
+input sample aspect ratio
+
+@item dar
+input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
+
+@item hsub, vsub
+horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+
+@item max_glyph_w
+maximum glyph width, that is the maximum width for all the glyphs
+contained in the rendered text
+
+@item max_glyph_h
+maximum glyph height, that is the maximum height for all the glyphs
+contained in the rendered text, it is equivalent to @var{ascent} -
+@var{descent}.
+
+@item max_glyph_a, ascent
+
+the maximum distance from the baseline to the highest/upper grid
+coordinate used to place a glyph outline point, for all the rendered
+glyphs.
+It is a positive value, due to the grid's orientation with the Y axis
+upwards.
+
+@item max_glyph_d, descent
+the maximum distance from the baseline to the lowest grid coordinate
+used to place a glyph outline point, for all the rendered glyphs.
+This is a negative value, due to the grid's orientation, with the Y axis
+upwards.
+
+@item n
+the number of input frame, starting from 0
+
+@item t
+timestamp expressed in seconds, NAN if the input timestamp is unknown
+@end table
+
+Some examples follow.
+
+@itemize
+
+@item
+Draw "Test Text" with font FreeSerif, using the default values for the
+optional parameters.
+
@example
drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
@end example
-will draw "Test Text" with font FreeSerif, using the default values
-for the optional parameters.
+@item
+Draw 'Test Text' with font FreeSerif of size 24 at position x=100
+and y=50 (counting from the top-left corner of the screen), text is
+yellow with a red box around it. Both the text and the box have an
+opacity of 20%.
-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.
+@item
+Show the text at the center of the video frame:
+@example
+drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
+@end example
+
+@item
+Show a text line sliding from right to left in the last row of the video
+frame. The file @file{LONG_LINE} is assumed to contain a single line
+with no newlines.
+@example
+drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t
+@end example
+
+@item
+Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
+@example
+drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
+@end example
+
+@item
+Draw a single green letter "g", at the center of the input video.
+The glyph baseline is placed at half screen height.
+@example
+drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent
+@end example
+
+@end itemize
+
For more information about libfreetype, check:
@url{http://www.freetype.org/}.
The @var{lut} filter requires either YUV or RGB pixel formats in
input, and accepts the options:
@table @option
-@var{c0} (first pixel component)
-@var{c1} (second pixel component)
-@var{c2} (third pixel component)
-@var{c3} (fourth pixel component, corresponds to the alpha component)
+@item c0
+first pixel component
+@item c1
+second pixel component
+@item c2
+third pixel component
+@item c3
+fourth pixel component, corresponds to the alpha component
@end table
The exact component associated to each option depends on the format in
The @var{lutrgb} filter requires RGB pixel formats in input, and
accepts the options:
@table @option
-@var{r} (red component)
-@var{g} (green component)
-@var{b} (blue component)
-@var{a} (alpha component)
+@item r
+red component
+@item g
+green component
+@item b
+blue component
+@item a
+alpha component
@end table
The @var{lutyuv} filter requires YUV pixel formats in input, and
accepts the options:
@table @option
-@var{y} (Y/luminance component)
-@var{u} (U/Cb component)
-@var{v} (V/Cr component)
-@var{a} (alpha component)
+@item y
+Y/luminance component
+@item u
+U/Cb component
+@item v
+V/Cr component
+@item a
+alpha component
@end table
The expressions can contain the following constants and functions:
@table @option
-@item E, PI, PHI
-the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), PHI (golden ratio)
-
@item w, h
the input width and heigth
lutyuv="y=negval:u=negval:v=negval"
# negate luminance
-lutyuv=negval
+lutyuv=y=negval
# remove chroma components, turns the video into a graytone image
lutyuv="u=128:v=128"
expressions containing the following constants:
@table @option
-@item E, PI, PHI
-the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), phi (golden ratio)
-
@item in_w, in_h
-the input video width and heigth
+the input video width and height
@item iw, ih
same as @var{in_w} and @var{in_h}
@item out_w, out_h
-the output width and heigth, that is the size of the padded area as
+the output width and height, that is the size of the padded area as
specified by the @var{width} and @var{height} expressions
@item ow, oh
the following constants:
@table @option
-@item E, PI, PHI
-the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), phi (golden ratio)
-
@item in_w, in_h
-the input width and heigth
+the input width and height
@item iw, ih
same as @var{in_w} and @var{in_h}
@item out_w, out_h
-the output (cropped) width and heigth
+the output (cropped) width and height
@item ow, oh
same as @var{out_w} and @var{out_h}
@item dar
input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
+@item sar
+input sample aspect ratio
+
@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.
The expression can contain the following constants:
@table @option
-@item PI
-Greek PI
-
-@item PHI
-golden ratio
-
-@item E
-Euler number
-
@item n
the sequential number of the filtered frame, starting from 0
@item PTS
the presentation timestamp in input
-@item PI
-Greek PI
-
-@item PHI
-golden ratio
-
-@item E
-Euler number
-
@item N
the count of the input frame, starting from 0.
It is mainly useful for testing timebase configuration.
It accepts in input an arithmetic expression representing a rational.
-The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
+The expression can contain the constants "AVTB" (the
default timebase), and "intb" (the input timebase).
The default value for the input is "intb".
@item frame_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
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 constant
"AVTB" (the default timebase), and defaults to the value "AVTB".
@section frei0r_src
projects / ffmpeg / blobdiff