Created attachment 530058 [details]
Relevant part of compiler output
Created attachment 532102 [details, diff]
Here is a patch fixing the build with >=media-video/ffmpeg-4.0.
It *should* also work with <media-video/ffmpeg-4.0, but I didn't check.
The first hunk of the patch is both wrong and unneeded:
The defines are not part of libavformat but libavcodec, AV_CODEC_FLAG_GLOBAL_HEADER was added in FFmpeg 2.8, AV_PKT_FLAG_KEY in FFmpeg 0.9.
(In reply to Andreas Sturmlechner from comment #4)
Should be fine in 3.4.1?
(In reply to Amy Liffey from comment #5)
> Should be fine in 3.4.1?
Correct! Built fine with 3.4.1-r4.