Feature request: Add AVS2 10-bit (davs2) decoder support

[yosh-wang]

Hello dear developer. Thank you for maintaining this excellent MPV build.

Could you consider adding decoding support for AVS2 (China's national video coding standard)? Especially with 10-bit color depth support.

Reason:

I have some CCTV 4K channel recording files, for example:

2026年中央广播电视总台春节联欢晚会.CCTV-4K.CMG.2026.Spring.Festival.Gala.20260216.2160p.50fps.UHDTV.AVS2.10bit.HLG.DD5.1-QHstudIo.ts

This file is encoded in AVS2 10bit HLG 4K 50fps. With the current version, playback shows a black screen and cannot play normally.

Benefits of adding this:

• Improves support for the AVS2 Chinese coding standard, making decoding functionality more complete
• Enables playback of Chinese 4K/8K ultra HD channel (e.g., CCTV) broadcast recordings
• Meets the needs of more Chinese users as well as international users who access Chinese ultra HD content

If you need a test sample, I can provide one.

Thank you!

[verygoodlee]

same answer as here mpv-player/mpv#17717 (comment) .

ffmpeg doesn't support decoding it, there‘s nothing can do on the mpv side.