mpv-0.29.0 with libav-git - demux/demux_lavf.c:321:19: error: implicit declaration of function 'av_demuxer_iterate';

[Coacher]

mpv version and platform

mpv-0.29.0 on Gentoo amd64.
Libav-git @ f25117a4286505b38c12466ef04459471de3c1b0.

Reproduction steps

Try to build mpv.

Expected behavior

mpv builds fine.

Actual behavior

mpv fails to build with:

../demux/demux_lavf.c: In function 'list_formats':
../demux/demux_lavf.c:321:19: error: implicit declaration of function 'av_demuxer_iterate'; did you mean 'av_buffer_create'? [-Werror=implicit-function-declaration]
     while ((fmt = av_demuxer_iterate(&iter)))
                   ^~~~~~~~~~~~~~~~~~
                   av_buffer_create
../demux/demux_lavf.c:321:17: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
     while ((fmt = av_demuxer_iterate(&iter)))
                 ^
../demux/demux_lavf.c: In function 'handle_new_stream':
../demux/demux_lavf.c:716:31: error: 'AV_DISPOSITION_DEPENDENT' undeclared (first use in this function); did you mean 'AV_DISPOSITION_DEFAULT'?
         if (st->disposition & AV_DISPOSITION_DEPENDENT)
                               ^~~~~~~~~~~~~~~~~~~~~~~~
                               AV_DISPOSITION_DEFAULT
../demux/demux_lavf.c:716:31: note: each undeclared identifier is reported only once for each function it appears in
../demux/demux_lavf.c: In function 'demux_lavf_control':
../demux/demux_lavf.c:1152:9: error: implicit declaration of function 'avformat_flush'; did you mean 'avio_flush'? [-Werror=implicit-function-declaration]
         avformat_flush(priv->avfc);
         ^~~~~~~~~~~~~~
         avio_flush
cc1: some warnings being treated as errors

Full build.log: https://paste.pound-python.org/show/5exoTvbp6xcbsLf6kXQG/

Additional info:

mpv-0.28.2 builds fine with the same configuration against the same libav library.

[ghost]

Explained in the readme

[jeeb]

Yea, unfortunately it probably didn't get noted enough. Effectively since Libav is pretty much in hibernation (most if not all developers are actively working on more interesting projects such as rav1e), and it never received these new APIs added on the FFmpeg side the support for it was pretty much effectively dropped.