first commit

app.py

@@ -0,0 +1,113 @@
+#!/usr/bin/env python3
+"""Doorbell JPEG proxy: prefetch from Frigate and serve a baseline 480px-wide JPEG."""
+
+from __future__ import annotations
+
+import hashlib
+import io
+import os
+import threading
+import time
+
+import requests
+from flask import Flask, request
+from PIL import Image
+
+FRIGATE_URL = os.environ.get(
+    "FRIGATE_URL", "http://10.0.1.197:5050/api/doorbell/latest.jpg?h=270"
+)
+TARGET_WIDTH = int(os.environ.get("TARGET_WIDTH", "480"))
+JPEG_QUALITY = int(os.environ.get("JPEG_QUALITY", "40"))
+FETCH_TIMEOUT = float(os.environ.get("FETCH_TIMEOUT", "5"))
+PREFETCH_HZ = float(os.environ.get("PREFETCH_HZ", "10"))
+
+app = Flask(__name__)
+
+_lock = threading.Lock()
+_jpeg = b""
+_etag = ""
+_width = 0
+_height = 0
+
+
+def _encode(frame: Image.Image) -> tuple[bytes, int, int]:
+    frame = frame.convert("RGB")
+    if frame.width != TARGET_WIDTH:
+        height = max(1, round(frame.height * TARGET_WIDTH / frame.width))
+        frame = frame.resize((TARGET_WIDTH, height), Image.BILINEAR)
+    buf = io.BytesIO()
+    frame.save(
+        buf,
+        format="JPEG",
+        quality=JPEG_QUALITY,
+        subsampling=2,
+        optimize=False,
+        progressive=False,
+    )
+    return buf.getvalue(), frame.width, frame.height
+
+
+def _prefetch_loop() -> None:
+    session = requests.Session()
+    interval = 1.0 / max(PREFETCH_HZ, 0.5)
+    while True:
+        started = time.monotonic()
+        try:
+            response = session.get(FRIGATE_URL, timeout=FETCH_TIMEOUT)
+            response.raise_for_status()
+            with Image.open(io.BytesIO(response.content)) as image:
+                encoded, width, height = _encode(image)
+            etag = '"' + hashlib.md5(encoded).hexdigest() + '"'
+            with _lock:
+                global _jpeg, _etag, _width, _height
+                _jpeg = encoded
+                _etag = etag
+                _width = width
+                _height = height
+        except Exception as exc:  # noqa: BLE001 — keep last good frame
+            print(f"prefetch failed: {exc}", flush=True)
+        delay = interval - (time.monotonic() - started)
+        if delay > 0:
+            time.sleep(delay)
+
+
+def _snapshot() -> tuple[bytes, str, int, int]:
+    with _lock:
+        return _jpeg, _etag, _width, _height
+
+
+@app.get("/")
+@app.get("/latest.jpg")
+def latest():
+    body, etag, width, height = _snapshot()
+    if not body:
+        return "Image not ready", 503, {"Content-Type": "text/plain"}
+
+    if request.headers.get("If-None-Match") == etag:
+        return ("", 304, {"ETag": etag, "Cache-Control": "no-cache"})
+
+    return (
+        body,
+        200,
+        {
+            "Content-Type": "image/jpeg",
+            "Content-Length": str(len(body)),
+            "ETag": etag,
+            "Last-Modified": time.strftime("%a, %d %b %Y %H:%M:%S GMT", time.gmtime()),
+            "Cache-Control": "no-cache",
+            "Accept-Ranges": "none",
+            "X-Image-Size": f"{width}x{height}",
+        },
+    )
+
+
+@app.get("/health")
+def health():
+    body, _, width, height = _snapshot()
+    status = 200 if body else 503
+    return {"ready": bool(body), "bytes": len(body), "size": f"{width}x{height}"}, status
+
+
+if __name__ == "__main__":
+    threading.Thread(target=_prefetch_loop, name="prefetch", daemon=True).start()
+    app.run(host="0.0.0.0", port=int(os.environ.get("PORT", "80")), threaded=True)