--- doc/indevs.texi | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/doc/indevs.texi b/doc/indevs.texi index 6951940a93..02d1cb3d86 100644 --- a/doc/indevs.texi +++ b/doc/indevs.texi @@ -462,6 +462,14 @@ Capture from CRTC ID 42 at 60fps, map the result to VAAPI, convert to NV12 and e ffmpeg -crtc_id 42 -framerate 60 -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,scale_vaapi=w=1920:h=1080:format=nv12' -c:v h264_vaapi output.mp4 @end example +@item +To capture only part of a plane the output can be cropped - this can be used to capture +a single window, as long as it has a known absolute position. For example, to capture +and encode the middle quarter of a 1920x1080 plane: +@example +ffmpeg -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,crop=960:540:480:270,scale_vaapi=format=nv12' -c:v h264_vaapi output.mp4 +@end example + @end itemize @section libndi_newtek -- 2.16.1
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