avfilter: add chromakey_cuda filter

GSoC'22

libavfilter/vf_chromakey_cuda.cu:the CUDA kernel for the filter
libavfilter/vf_chromakey_cuda.c: the C side that calls the kernel and gets user input
libavfilter/allfilters.c: added the filter to it
libavfilter/Makefile: added the filter to it
cuda/cuda_runtime.h: added two math CUDA functions that are used in the filter

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

1 files changed, 43 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 603b0ff3f8..40f21fb34c 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -8599,6 +8599,7 @@ The command accepts the same syntax of the corresponding option.
 If the specified expression is not valid, it is kept at its current
 value.
 
+@anchor{chromakey}
 @section chromakey
 YUV colorspace color/chroma keying.
 
@@ -8651,6 +8652,48 @@ ffmpeg -f lavfi -i color=c=black:s=1280x720 -i video.mp4 -shortest -filter_compl
 @end example
 @end itemize
 
+@section chromakey_cuda
+CUDA accelerated YUV colorspace color/chroma keying.
+
+This filter works like normal chromakey filter but operates on CUDA frames.
+for more details and parameters see @ref{chromakey}.
+
+@subsection Examples
+
+@itemize
+@item
+Make all the green pixels in the input video transparent and use it as an overlay for another video:
+
+@example
+./ffmpeg \
+    -hwaccel cuda -hwaccel_output_format cuda -i input_green.mp4  \
+    -hwaccel cuda -hwaccel_output_format cuda -i base_video.mp4 \
+    -init_hw_device cuda \
+    -filter_complex \
+    " \
+        [0:v]chromakey_cuda=0x25302D:0.1:0.12:1[overlay_video]; \
+        [1:v]scale_cuda=format=yuv420p[base]; \
+        [base][overlay_video]overlay_cuda" \
+    -an -sn -c:v h264_nvenc -cq 20 output.mp4
+@end example
+
+@item
+Process two software sources, explicitly uploading the frames:
+
+@example
+./ffmpeg -init_hw_device cuda=cuda -filter_hw_device cuda \
+    -f lavfi -i color=size=800x600:color=white,format=yuv420p \
+    -f lavfi -i yuvtestsrc=size=200x200,format=yuv420p \
+    -filter_complex \
+    " \
+        [0]hwupload[under]; \
+        [1]hwupload,chromakey_cuda=green:0.1:0.12[over]; \
+        [under][over]overlay_cuda" \
+    -c:v hevc_nvenc -cq 18 -preset slow output.mp4
+@end example
+
+@end itemize
+
 @section chromanr
 Reduce chrominance noise.