orklev2-coreaudio

name	orklev2-coreaudio
description	Answer questions about orkid's CoreAudio backend (macOS), AudioUnit graph, HAL input/output callbacks, AuContext, CoreAudioDevice, stereo fragment pools, and how CoreAudio drives the Singularity synth engine. Use when the user asks about CoreAudio, AudioUnit, or macOS audio output.
user-invocable	false

Orkid CoreAudio Backend Reference

When answering questions about the CoreAudio backend in orkid, consult the files below. All under ork.lev2/.

Key Files

Component	File
AudioDevice Base	inc/ork/lev2/aud/audiodevice.h
CoreAudioDevice	src/aud/coreaudio/CoreAudioDevice.h
CoreAudioDevice Impl	src/aud/coreaudio/CoreAudioDevice.cpp
AuContext (AudioUnit)	src/aud/coreaudio/au.h, au.cpp
I/O Callbacks	src/aud/coreaudio/au_io.cpp
Config Flags	inc/ork/lev2/config.h (ENABLE_CORE_AUDIO)
Factory	src/aud/audiodevice.cpp

Architecture

CoreAudioDevice
  └─ AuContext
       ├─ AUGraph (AudioUnit graph)
       │   ├─ _inputUnit (HAL input)
       │   └─ _outputUnit (HAL output)
       ├─ _inputProc() → LayerFragment → _inputQueue
       └─ _outputProc() ← StereoFragment ← _outputQueue
                              ↑
                    Singularity synth.compute()

CoreAudioDevice

• _the_synth — Singularity synth instance
• _aucontext — AudioUnit context managing the graph
• _inputDevList / _outputDevList — enumerated CoreAudio devices
• _actual_input_channels — resolved input channel count

Startup Flow

1. Get device info for input/output
2. Create Singularity synth instance
3. Create AuContext
4. _aucontext->Init() → build AudioUnit graph
5. _aucontext->Start() → begin audio processing

AuContext

Member	Description
_graph	AUGraph (AudioUnit processing graph)
_inputUnit / _outputUnit	HAL AudioUnits
_inputBuffer	AudioBufferList for input
_outputPool / _inputPool	Object pools for audio fragments
_outputQueue / _inputQueue	MpMcBoundedQueue (4096 entries)

Graph Configurations

• setupGraphForInputOnly() — input-only HAL unit
• setupGraphForOutputOnly() — output-only HAL unit
• setupGraphForIO() — bidirectional I/O

Callbacks (au_io.cpp)

Input Callback (_inputProc)

1. AudioUnitRender() — pull data from HAL
2. De-interleave into LayerFragment
3. Push to _inputQueue
4. Delivered as AudioInputChunk to consumer

Output Callback (_outputProc)

1. Timing synchronization with input device (sample timestamps)
2. Pop StereoFragment from _outputQueue
3. Interleave L/R channels into output buffer
4. Return buffer to pool

Configuration

• Sample Rate: 48000 Hz (hardcoded)
• Buffer Size: desired_framesize (default 1024, configurable via env)
• Format: Float32 (CoreAudio native)
• Channels: Stereo output, mono/stereo input

Connection to Singularity

The synth thread calls synth->compute(numframes, inputbuffer) which writes to synth->_obuf._leftBuffer / _obuf._rightBuffer. The output callback reads these into StereoFragment buffers queued for the HAL output.

How to Answer

1. For CoreAudioDevice: check CoreAudioDevice.h and .cpp
2. For AudioUnit graph: check au.h and au.cpp
3. For I/O callbacks: check au_io.cpp
4. For base AudioDevice interface: check audiodevice.h
5. For Singularity integration: consult orklev2-audio skill