colormatrix filter fails with hwaccel

[Mark Sanders]

Summary of the trouble:

When using the "colormatrix" filter with hwaccel enabled for GPU transcoding the process fails. The matrix translation is required when different color spaces are used (BT.709 for HD, BT.601 for SD, BT.2020 for UHD).

Here an example to reproduce:

ffmpeg -hwaccel qsv \
 -c:v h264_qsv \
 -i input.ts \
 -filter_complex "[i:256]deinterlace_qsv,scale_qsv=720:576,fps=25,colormatrix=bt709:bt601[out]" \
 -map [out] -map i:257
 -c:0 mpeg2_qsv -preset medium \
 -c:1 copy \
 -f mpegts output.ts

So, the "colormatrix" filter needs to be enhanced to support a GPU context.

Regards.

[Elon Musk]

Colormatrix is obsolete and broken. There is no need to use it at all.

[Mark Sanders]

OK. Thank you!