pi features docs

pi/contents_server.py

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+"""
+Contents server — serves alarm audio and status images over WebSocket.
+
+Streams WAV PCM chunks and pushes 1-bit monochrome status images to the
+connected ESP32 dashboard client on port 8766.
+
+Protocol:
+  Status image:
+    1. Text frame:  {"type":"status_image","width":120,"height":120}
+    2. Binary frame: 1-bit monochrome bitmap
+
+  Alarm audio:
+    1. Text frame:  {"type":"alarm_start","sample_rate":N,"channels":N,"bits":N}
+    2. Binary frames: raw PCM chunks (4096 bytes each, paced at ~90% real-time)
+    3. Text frame:  {"type":"alarm_stop"}
+"""
+
+import asyncio
+import logging
+from random import randint
+
+import websockets
+
+from audio_handler import find_wav, read_wav, stream_alarm
+from image_handler import IMG_DIR, load_status_image, send_status_image
+
+logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(message)s")
+log = logging.getLogger("contents_server")
+
+PORT = 8766
+
+
+async def handler(ws):
+    """Handle a single WebSocket connection."""
+    remote = ws.remote_address
+    log.info("Client connected: %s:%d", remote[0], remote[1])
+
+    wav_path = find_wav()
+    pcm, sr, ch, bits = read_wav(wav_path)
+
+    # Load status images
+    img_idle = load_status_image(IMG_DIR / "idle.png")
+    img_alarm = load_status_image(IMG_DIR / "on_alarm.png")
+
+    try:
+        # Send idle image on connect
+        await send_status_image(ws, img_idle)
+
+        while True:
+            delay = randint(30, 60)
+            log.info("Next alarm in %ds", delay)
+            await asyncio.sleep(delay)
+
+            # Switch to alarm image before audio
+            await send_status_image(ws, img_alarm)
+            await stream_alarm(ws, pcm, sr, ch, bits)
+            # Switch back to idle after alarm
+            await send_status_image(ws, img_idle)
+    except websockets.exceptions.ConnectionClosed:
+        log.info("Client disconnected: %s:%d", remote[0], remote[1])
+
+
+async def main():
+    log.info("Contents server starting on port %d", PORT)
+    async with websockets.serve(handler, "0.0.0.0", PORT):
+        await asyncio.Future()  # run forever
+
+
+if __name__ == "__main__":
+    asyncio.run(main())