orklev2-portaudio

name	orklev2-portaudio
description	Answer questions about orkid's PortAudio backend (cross-platform), callback-based audio, device selection by short ID, int16 input / float output, CPU load tracking, and how PortAudio drives the Singularity synth. Use when the user asks about PortAudio or cross-platform audio.
user-invocable	false

Orkid PortAudio Backend Reference

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

Key Files

Component	File
AudioDevice Base	inc/ork/lev2/aud/audiodevice.h
AudioDevicePa	src/aud/portaudio/audiodevice_pa.h
Implementation	src/aud/portaudio/audiodevice_pa.cpp
Config Flags	inc/ork/lev2/config.h (ENABLE_PORTAUDIO)

Architecture

Single-callback model — PortAudio calls patestCallback() on its audio thread:

PortAudio Thread (patestCallback)
  ├─ Input: int16_t* → convert to float → AudioInputChunk → _input_handler
  ├─ synth->compute(numframes, inputbuffer)
  └─ Output: synth->_obuf._leftBuffer/_rightBuffer → interleave → float* output

AudioDevicePa

• _the_synth — Singularity synth instance
• PaImpl._stream — PortAudio stream handle
• PaImpl._input_override / _output_override — device index overrides
• PaImpl._actual_input_channels — resolved channel count

Callback (patestCallback)

Input Processing:

1. Check _input_handler callback
2. Convert int16 → float, handle stereo→mono mixing
3. Call handler with AudioInputChunk

Output Processing:

1. synth->compute(framesPerBuffer, inputbuffer)
2. Read synth->_obuf._leftBuffer / _rightBuffer
3. Interleave to float output buffer
4. Track CPU load: Pa_GetStreamCpuLoad()

Configuration

Parameter	Value
Input Format	int16_t (paInt16)
Output Format	float (paFloat32)
Sample Rate	From getSampleRate()
Frames/Buffer	128 (macOS), 256 (Linux)

Device Selection

• Resolves 4-char base36 short IDs to full device names
• Enumerates all PortAudio devices via Pa_GetDeviceCount()
• Matches by name and channel requirements
• Pa_OpenStream() with selected devices → Pa_StartStream()

Platform Notes

• macOS: Default backend when CoreAudio not selected; 128 frame buffer for lower latency
• Linux: Available alongside ALSA and PipeWire; 256 frame buffer

How to Answer

1. For PortAudio device: check audiodevice_pa.h and .cpp
2. For base interface: check audiodevice.h
3. For Singularity integration: consult orklev2-audio skill