avfilter/vf_chromakey: Add chromakey video filter

Signed-off-by: Timo Rothenpieler <timo@rothenpieler.org>

1 files changed, 45 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 88f6093049..044876c7c7 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -3707,6 +3707,51 @@ boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chrom
 @end example
 @end itemize
 
+@section chromakey
+YUV colorspace color/chroma keying.
+
+The filter accepts the following options:
+
+@table @option
+@item color
+The color which will be replaced with transparency.
+
+@item similarity
+Similarity percentage with the key color.
+
+0.01 matches only the exact key color, while 1.0 matches everything.
+
+@item blend
+Blend percentage.
+
+0.0 makes pixels either fully transparent, or not transparent at all.
+
+Higher values result in semi-transparent pixels, with a higher transparency
+the more similar the pixels color is to the key color.
+
+@item yuv
+Signals that the color passed is already in YUV instead of RGB.
+
+Litteral colors like "green" or "red" don't make sense with this enabled anymore.
+This can be used to pass exact YUV values as hexadecimal numbers.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Make every green pixel in the input image transparent:
+@example
+ffmpeg -i input.png -vf chromakey=green out.png
+@end example
+
+@item
+Overlay a greenscreen-video on top of a static black background.
+@example
+ffmpeg -f lavfi -i color=c=black:s=1280x720 -i video.mp4 -shortest -filter_complex "[1:v]chromakey=0x70de77:0.1:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.mkv
+@end example
+@end itemize
+
 @section codecview
 
 Visualize information exported by some codecs.