GitLab

Highlights:

  - amrparse, aacparse, ac3parse, flacparse, mpegaudioparse, dcaparse audio parsers (moved from -bad)
  - muxers now mux based on running time
  - ISO MP4 muxers: mp4mux/3gppmux/qtmux/mj2mux (moved from -bad)
  - new matroskaparse element
  - new v4l2radio element
  - rtpsession: support RTCP Early Feedback (the AVPF profile)
  - orc 0.4.14 or newer recommended
  - many other fixes and improvements

"Low" etc. are quality settings here (e.g. for the internal resampler).
Some day when we use GLib's i18n functions we might want to use
NC_() and g_dpgettext2() here instead of the comments.

Fixes #555967.