signals fails to build with newest FFmpeg.

[jackjansen]

Updated the world today (to create a branch to prepare for the release of cwipc v8.0 and the API changes that will need), and builds fail.

It seems that ffmpeg has been updated (in vcpkg) to a newer version, and we had been using some methods that were deprecated and have now gone.

I think the problems are within signals. Here is the first error message:

[build] /Users/jack/src/VRTogether/lldash/signals/src/lib_media/common/libav.cpp:39:3: error: use of undeclared identifier 'avcodec_close'; did you mean 'avio_close'?
[build]    39 |   avcodec_close(p);

A quick google found this issue in some other repo that seems to be similar: joncampbell123/dosbox-x#5803

If you don't have time to look at this please assign back, then I'll have a look (but I'm hoping you will have a better idea than me:-)

[jackjansen]

I've backed out my update of vcpkg on my #104 branch, and that seems to work. So no hurry. Just something we need to do at some point.

[rbouqueau]

I agree we'll have to address this at some point in time, but we should control "when", don't we? :)

I checked and it seems it's only done for gpac here. Should we extend this to FFmpeg (and probably most other deps) as well ?

[cwidisgroup]

I have the feeling this is a different issue: signals use ffmpeg APIs that were apparently deprecated in ffmpeg v7, and they have now disappeared in ffmpeg v8.

[rbouqueau]

Ok but FFmpeg versions down to FFmpeg 5 is still officially supported. Do we need any FFmpeg 8 feature? If not, can't we just freeze FFmpeg on the v7 branch for now?

I know we'll need to update to a more recent FFmpeg. But I also hope that by that time someone from the community will drive such a change, not us-poor-maintainers :)