Also introduce default output format and selected device format, should the
user want another format.
As part of this, change enum player_format in player.h to enum media_format in
misc.h so that it is akin to struct media_quality.
Modify json API to support this.
Should make it easier to add/remove parameters without changing all calls to the
functions throughout the code.
Also adds an interface through which to call make_mp4_header().
- Calculate size for both formats (+ move the return to transcode_encode_query)
- Let transcode_needed() decide what format to output
- Determine content-type from transcoding type
- Add transcode-dependent ability to override file metadata in rsp/daap
- Send file size matching format
ffmpeg 6 requires fixed size frames for the encoder, so this commit refactors
the mp3 streaming to do support that. Also uses outputs_quality_subscribe which
potentially has better performance (e.g. a 48000 sample rate source will only
be resampled once if both airplay and mp3 streaming want 44100), and makes it
easier to create fixed size frames.
Resolves#1601
