audio Directory Reference

Directory dependency graph for audio:

Files
	audio_sink.h
	decoder.c
	Decoder facade: owns the FILE*, auto-detects the format, delegates to a backend.
	decoder.h
	Audio file decoder: turns an MP3 or WAV file into interleaved PCM frames.
	decoder_backend.h
	Internal contract between the decoder facade (decoder.c) and a format backend.
	decoder_mp3.c
	MP3 backend: libhelix (fixed-point) decoding one frame per decoder_read().
	decoder_wav.c
	WAV backend: PCM RIFF/WAVE, 16-bit or 24-bit, mono or stereo, up to 192 kHz.
	mp3_frame.c
	MPEG Layer III header + Xing/Info/VBRI parsing (see mp3_frame.h).
	mp3_frame.h
	Internal MPEG-1/2 Layer III header + VBR-tag (Xing/Info/VBRI) parsing.
	pipeline.c
	Audio pipeline task: producer->consumer loop from a PCM source to a selectable sink (wired DAC or Bluetooth).
	pipeline.h
	Audio pipeline: the real-time task that pulls PCM from a source and pushes it to an Audio sink interface.
	player.c
	Playback transport state machine over the playlist and pipeline.
	player.h
	Playback transport: the orchestrator that turns the playlist into sound.
	playlist.c
	playlist.h
	Play order and navigation over the Storage service index: what to play next.
	sink_bluetooth.c
	Bluetooth A2DP audio sink: bridge the push pipeline to the pull A2DP source.
	sink_bluetooth.h
	Bluetooth A2DP audio sink: stream PCM to a connected speaker.
	sink_i2s_dac.c
	sink_i2s_dac.h
	Wired output path control: PCM5242 analog mute (XSMT) and MAX97220 amp shutdown.
	track_meta.c
	Tags + format reader (see track_meta.h): MP3 ID3v2/ID3v1, WAV header, no playback.
	track_meta.h
	Read a track's tags and format without playing it.
	volume.c
	Volume service: pot -> active output (DAC byte or Bluetooth AVRCP), deadband write.
	volume.h
	Volume service: maps the pot to whichever output is active (DAC, Bluetooth, or none).