Implement the "scan_stream" method that can read tags from any
input_stream object.  This requires a FLAC__IOCallbacks implementation
based on the input_stream API.

Merge common code.

Not using libFLAC++ because this library adds a lot of overhead due to
virtual method calls.  This new class library is zero-overhead.

This has been deprecated by the "embcue" playlist plugin.

Allow the function to be cancelled.

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

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/

Add GMutex, GCond attributes which will be used by callers to
conditionally wait on the stream.

Remove the (now-useless) plugin method buffer(), wait on GCond
instead.  Lock the input_stream before each method call.  Do the same
with the playlist plugins.

Fix clang warning.

Adds mixrampdb and mixrampdelay commands.  Reads MIXRAP_START and
MIXRAMP_END tags from FLAC files and overlaps instead of crossfading.

Invoke decoder_initialized() in the libFLAC metadata callback.  This
merges code from the FLAC and the OggFLAC decoder plugin into the
common library.

This feature has been moved to the "flac" playlist plugin.

Make this code is reusable.

Make it X_decoder_plugin.c.

Support deprecated MIME types such as "audio/x-ogg".  Support new
types such as "audio/flac".

Return FLAC__STREAM_DECODER_SEEK_STATUS_UNSUPPORTED if this input
stream does not support seeking.

Remove the audio_format attribute, add "frame_size" instead.  The
audio_format initialization and check is moved both to
flac_data_get_audio_format().

Use the sample rate stored in the stream_info struct instead of the
audio_format struct.

Don't update a float timestamp, this will make imprecisions add up
after a while.  We already have the number of the current frame, let's
just calculate the float timestamp from that for every decoder_data()
command.  For this, we need to add the attribute "first_frame", for
CUE sheet songs.

Removed the "bit_rate" attribute from the flac_data struct.  Pass the
number of bytes since the last call to flac_common_write(), and let
it calculate the bit rate.

We don't want to work with floating point values if possible.  Get the
integer number of frames from the FLAC__StreamMetadata_StreamInfo
object, and convert it into a float duration on demand.  This patch
adds a check if the STREAMINFO packet has been received yet.

Wrapper for FLAC__stream_decoder_process_until_end_of_metadata(),
decoder_initialized().

Convenience wrapper for FLAC__stream_decoder_new() and
FLAC__stream_decoder_set_metadata_respond().

Free the pointer right after its last use, i.e. after the
FLAC__stream_decoder_init_file() call.