refactor: check ret before write fps + show filesize

src/app.py

@@ -27,11 +27,10 @@ def video_reader():
     while True:
         ret, frame = cap.read()
 
-        cv2.putText(frame, f"{measured_fps: .0f}", (frame.shape[1] - 70, 30), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 0), 2, cv2.LINE_AA)
-        ret, jpeg = cv2.imencode('.jpg', frame)
         if ret:
             with lock:
-                latest_frame = jpeg.tobytes()
+                cv2.putText(frame, f"{measured_fps: .0f}", (frame.shape[1] - 70, 30), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 0), 2, cv2.LINE_AA)
+                latest_frame = frame
         frame_count += 1
 
         # measure FPS
@@ -52,7 +51,10 @@ def video_reader():
 def generate():
     while True:
         with lock:
-            frame_bytes = latest_frame
+            encode_param = [int(cv2.IMWRITE_JPEG_QUALITY), 50]
+            ret, jpeg = cv2.imencode('.jpg', latest_frame, encode_param)
+            frame_bytes = jpeg.tobytes() if ret else None
+            print(f"frame filesize: {len(frame_bytes) / (1024 * 1024):.4f} MB")
         if frame_bytes is not None:
             yield (b'--frame\r\n'b'Content-Type: image/jpeg\r\n\r\n' + frame_bytes + b'\r\n')