Function startSoxRecording

src/services/voice.ts:426–494

(
  onData: (chunk: Buffer) => void,
  onEnd: () => void,
  options?: { silenceDetection?: boolean },
)

}

function startSoxRecording(
  onData: (chunk: Buffer) => void,
  onEnd: () => void,
  options?: { silenceDetection?: boolean },
): boolean {
  const useSilenceDetection = options?.silenceDetection !== false

  // Record raw PCM: 16 kHz, 16-bit signed, mono, to stdout.
  // --buffer 1024 forces SoX to flush audio in small chunks instead of
  // accumulating data in its internal buffer. Without this, SoX may buffer
  // several seconds of audio before writing anything to stdout when piped,
  // causing zero data flow until the process exits.
  const args = [
    '-q', // quiet
    '--buffer',
    '1024',
    '-t',
    'raw',
    '-r',
    String(RECORDING_SAMPLE_RATE),
    '-e',
    'signed',
    '-b',
    '16',
    '-c',
    String(RECORDING_CHANNELS),
    '-', // stdout
  ]

  // Add silence detection filter (auto-stop on silence).
  // Omit for push-to-talk where the user manually controls start/stop.
  if (useSilenceDetection) {
    args.push(
      'silence', // start/stop on silence
      '1',
      '0.1',
      SILENCE_THRESHOLD,
      '1',
      SILENCE_DURATION_SECS,
      SILENCE_THRESHOLD,
    )
  }

  const child = spawn('rec', args, {
    stdio: ['pipe', 'pipe', 'pipe'],
  })

  activeRecorder = child

  child.stdout?.on('data', (chunk: Buffer) => {
    onData(chunk)
  })

  // Consume stderr to prevent backpressure
  child.stderr?.on('data', () => {})

  child.on('close', () => {
    activeRecorder = null