avfilter: add paletteuse filter

1 files changed, 50 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 7789bf0cac..191b52f52e 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -6909,6 +6909,7 @@ pad="2*iw:2*ih:ow-iw:oh-ih"
 @end example
 @end itemize
 
+@anchor{palettegen}
 @section palettegen
 
 Generate one palette for a whole video stream.
@@ -6954,6 +6955,55 @@ ffmpeg -i input.mkv -vf palettegen palette.png
 @end example
 @end itemize
 
+@section paletteuse
+
+Use a palette to downsample an input video stream.
+
+The filter takes two inputs: one video stream and a palette. The palette must
+be a 256 pixels image.
+
+It accepts the following options:
+
+@table @option
+@item dither
+Select dithering mode. Available algorithms are:
+@table @samp
+@item bayer
+Ordered 8x8 bayer dithering (deterministic)
+@item heckbert
+Dithering as defined by Paul Heckbert in 1982 (simple error diffusion).
+Note: this dithering is sometimes considered "wrong" and is included as a
+reference.
+@item floyd_steinberg
+Floyd and Steingberg dithering (error diffusion)
+@item sierra2
+Frankie Sierra dithering v2 (error diffusion)
+@item sierra2_4a
+Frankie Sierra dithering v2 "Lite" (error diffusion)
+@end table
+
+Default is @var{sierra2_4a}.
+
+@item bayer_scale
+When @var{bayer} dithering is selected, this option defines the scale of the
+pattern (how much the crosshatch pattern is visible). A low value means more
+visible pattern for less banding, and higher value means less visible pattern
+at the cost of more banding.
+
+The option must be an integer value in the range [0,5]. Default is @var{2}.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Use a palette (generated for example with @ref{palettegen}) to encode a GIF
+using @command{ffmpeg}:
+@example
+ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif
+@end example
+@end itemize
+
 @section perspective
 
 Correct perspective of video not recorded perpendicular to the screen.