[vlc-devel] Add new API to libvlc for persistent equalizer settings.

[Mark Lee]

Another patch for libvlc equalizer.

The significant changes in this patch as compared to previous patches on the same subject are:

1. remove the equalizer-enabled callback in the audio output core;
2. in libvlc_media_player_play re-enable the equalizer filter if needed.

The recent multitude of patches on this subject has been to address various issues with keeping the equalizer settings active when starting/stopping media, or playing new media.

The already existing video adjustment API (which is conceptually similar) does *not* preserve settings in those same use-cases. That approach would have made the equalizer implementation simpler, but much less useful IMHO.

If the approach in this patch is still wrong, then I really don't think I have anywhere else to go with it and I'll reluctantly admit defeat. :(

The test case in patch 2/2 is integrated with the existing "make check" process.