pi features docs

pi/audio_handler.py

@@ -0,0 +1,64 @@
+"""Audio alarm functions — WAV loading and PCM streaming."""
+
+import asyncio
+import json
+import logging
+import wave
+from pathlib import Path
+
+log = logging.getLogger(__name__)
+
+CHUNK_SIZE = 4096
+AUDIO_DIR = Path(__file__).parent / "assets" / "alarm"
+
+
+def find_wav() -> Path:
+    """Find the first .wav file in the alarm assets directory."""
+    wavs = list(AUDIO_DIR.glob("*.wav"))
+    if not wavs:
+        raise FileNotFoundError(f"No .wav files found in {AUDIO_DIR}")
+    log.info("Using audio file: %s", wavs[0].name)
+    return wavs[0]
+
+
+def read_wav(path: Path) -> tuple[bytes, int, int, int]:
+    """Read WAV file and return (pcm_data, sample_rate, channels, bits_per_sample)."""
+    with wave.open(str(path), "rb") as wf:
+        sr = wf.getframerate()
+        ch = wf.getnchannels()
+        bits = wf.getsampwidth() * 8
+        pcm = wf.readframes(wf.getnframes())
+    log.info("WAV loaded: %dHz %dch %dbit, %.1fs, %d bytes",
+             sr, ch, bits, len(pcm) / (sr * ch * (bits // 8)), len(pcm))
+    return pcm, sr, ch, bits
+
+
+def chunk_bytes(data: bytes, size: int):
+    """Yield data in fixed-size chunks."""
+    for i in range(0, len(data), size):
+        yield data[i : i + size]
+
+
+async def stream_alarm(ws, pcm: bytes, sr: int, ch: int, bits: int):
+    """Stream one alarm cycle to the connected client."""
+    bytes_per_sec = sr * ch * (bits // 8)
+    chunk_duration = CHUNK_SIZE / bytes_per_sec
+    pace_delay = chunk_duration * 0.9  # 90% real-time to avoid underrun
+
+    total_chunks = (len(pcm) + CHUNK_SIZE - 1) // CHUNK_SIZE
+
+    start_msg = json.dumps({
+        "type": "alarm_start",
+        "sample_rate": sr,
+        "channels": ch,
+        "bits": bits,
+    })
+    await ws.send(start_msg)
+    log.info("Sent alarm_start (%d chunks, pace %.1fms)", total_chunks, pace_delay * 1000)
+
+    for i, chunk in enumerate(chunk_bytes(pcm, CHUNK_SIZE)):
+        await ws.send(chunk)
+        await asyncio.sleep(pace_delay)
+
+    await ws.send(json.dumps({"type": "alarm_stop"}))
+    log.info("Sent alarm_stop")