doc: new a52 input formats, global config

alsa-project/alsa-plugins pull request #30 was opened from quequotion:

Document the new preconfiguration and libavcodec version-dependent input formats, fixes #29.

Note: I haven't documented specifically which version of libavcodec determines which input format.

I got pretty confused trying to pin the commits that switched from linear to planar, and 16bit to 32bit to specific versions of libavcodec.

If we need that documented, I need some help with that.

Let me know if I got anything wrong!

Request URL : https://github.com/alsa-project/alsa-plugins/pull/30 Patch URL : https://github.com/alsa-project/alsa-plugins/pull/30.patch Repository URL: https://github.com/alsa-project/alsa-plugins