Update app.py

app.py

@@ -266,6 +266,8 @@ def video_frame_callback(frame: av.VideoFrame) -> av.VideoFrame:
         cv2.putText(img, 'OpenCV', (50, 50), cv2.FONT_HERSHEY_SIMPLEX, 2, (255, 255, 255), 1, cv2.LINE_AA)
 
         result_queue.put(hands)
+        
+    return av.VideoFrame.from_ndarray(img, format="bgr24")
 
 # def video_frame_callback(frame: av.VideoFrame) -> av.VideoFrame:
 #     global indexImg, output_text