try space

app.py

@@ -61,7 +61,7 @@ async def Video(video_file: UploadFile = File(...),kind_back: str = Form(...), b
         #nparr = np.frombuffer(video_data, np.uint8)
         #video_path=cv2.imdecode(nparr, cv2.IMREAD_COLOR) #named this as just passed as it's path
 
-        video_path = f'/tmp/tmptmp.mp4'#{video_file.filename}
+        video_path = f'/tmp/tmptmp.avi'#{video_file.filename}
         with open(video_path, 'wb') as f:
             f.write(await video_file.read())
 

server.py

@@ -159,7 +159,7 @@ class SegmenterBackground():
         #number_frames= int(cv2.CAP_PROP_FRAME_COUNT)
         
         # Define the codec and create VideoWriter object to save the output video
-        fourcc = cv2.VideoWriter_fourcc(*'XVID')
+        fourcc = cv2.VideoWriter_fourcc(*'XVID')#avi ,mp4?? H264: This is the most widely used video compression standard for MP4 files.
         out = cv2.VideoWriter(output_path, fourcc, fps, (frame_width, frame_height))
         if isinstance(background_image, Image.Image):
             background_image = background_image.resize((640, 480))