For simplicity, the MPD core should not have to deal with packing.  It
is rarely used, and those plugins that need it should use the
pcm_export library instead.

Don't use audio_format.reverse_endian.

This format is unused since the DSDIFF decoder plugin now reverses the
bit order.

Allow to remove this complexity from the MPD core.

Move the responsibility for the conversion to the PCM library.  This
will allow passing the verbatim DSD samples to an output plugin.

Basic support for Direct Stream Digital.  No conversion yet, and no
decoder/output plugin support.

This might break older versions, I didn't test.

This was disabled when compiled with a new ffmpeg version.  Older
ffmpeg versions used it explicitly, while newer ones may pass it
through from the codec.

Prepare for big CUESHEET tags.

The new method pair() receives an arbitrary name/value pair.  Support
for this is being added to a few decoder plugins.

Remove clutter from wavpack_scan_file(), and use a (large) fixed
buffer for the tag item.

Fixes build regression.

Pass a callback table to scan_file() and scan_stream(), instead of
returning a tag object.

When gme_track_info() returns with success, then the gme_info_t
pointer must be set.

All supported ffmpeg/libav versions have this.

The only other libFLAC call (seek) does not produce fatal errors.

Call it in the function that also invokved
FLAC__stream_decoder_init_*().

https://www.xkcd.com/292/

The struct is smaller because it is sparse.  Its traversal is also
more efficient.

Implements support for libavcodec 0.9, which removes the compatibility
macros SAMPLE_FMT_*

Minor optimisation.

Use the tag_item_names table to look up the names of all MPD tags, and
remove the duplicate entries from ffmpeg_tag_maps.

Allow using this function without the ffmpeg_tag_map struct.

Eliminate some duplicate code.

Move the #ifdefs out of _copy_metadata().

No interest in this return value.

Require libavutil 51.5.0.

This function was added when the libavformat version was 53.2.0, but
the actual release 53.2.0 did not have it.