improvement: FPS counter + frame timing

src/app.py

@@ -7,31 +7,47 @@ app = Flask(__name__)
 
 latest_frame = None
 lock = threading.Lock()
+measured_fps = 0
 
 def video_reader():
-    global latest_frame
+    global latest_frame, lock, measured_fps
+
     cap = cv2.VideoCapture('videos/classroom.mp4')
     framerate = cap.get(cv2.CAP_PROP_FPS)
-    frame_duration = 1.0 / framerate if framerate > 0 else 1.0 / 30
-    
-    latest_frame_accessed_time = time.time()
+    frame_duration = 1 / framerate
 
+    # variables to measure FPS
+    frame_count = 0
+    last_time = time.time()
+    rolling_duration = 0.5
+
+    # variables to control framerate
+    next_frame_time = time.time()
+    
     while True:
-        start_time = time.time()
         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()
-        elapsed = time.time() - start_time
+        frame_count += 1
 
-        print(f"{1/(time.time() - latest_frame_accessed_time)} FPS")
-        latest_frame_accessed_time = time.time()
+        # measure FPS
+        now = time.time()
+        if now - last_time >= rolling_duration:
+            measured_fps = frame_count / (now - last_time)
+            frame_count = 0
+            last_time = now
 
-        sleep_time = frame_duration - elapsed
+        # control framerate
+        next_frame_time += frame_duration
+        sleep_time = next_frame_time - time.time()
         if sleep_time > 0:
             time.sleep(sleep_time)
+        else:
+            next_frame_time = time.time()
 
 def generate():
     while True: