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• OpenCV is able to read the stream but VLC not

  25 avril 2023, par Ahmet Çavdar

  I'm trying to stream my webcam frames to an UDP address. Here is my sender code.

  


  cmd = ['ffmpeg', '-y', '-f', 'rawvideo', '-pixel_format', 'bgr24', '-video_size', f'{width}x{height}', 
       '-i', '-', '-c:v', 'mpeg4','-preset', 'ultrafast', '-tune', 'zerolatency','-b:v', '1.5M',
       '-f', 'mpegts', f'udp://@{ip_address}:{port}']
p = subprocess.Popen(cmd, stdin=subprocess.PIPE)
camera = cv2.VideoCapture(0)
while True:
    ret, frame = camera.read()
    cv2.imshow("Sender",frame)
    if not ret:
        break
    p.stdin.write(frame.tobytes())
    p.stdin.flush()
    if cv2.waitKey(1) & 0xFF == ord('q'):
            break


  


  This Python code can make stream successfully. I can read the stream with this receiver code.

  


  q = queue.Queue()
def receive():
    cap = cv2.VideoCapture('udp://@xxx.x.xxx.xxx:5000')
    ret, frame = cap.read()
    q.put(frame)
    while ret:
        ret, frame = cap.read()
        q.put(frame)
def display():
    while True:
        if q.empty() != True:
            frame = q.get()
            cv2.imshow('Receiver', frame)
        k = cv2.waitKey(1) & 0xff
        if k == 27:  # press 'ESC' to quit
            break
tr = threading.Thread(target=receive, daemon=True)
td = threading.Thread(target=display)
tr.start()
td.start()
td.join()


  


  But I can not watch the stream from VLC. I'm going to Media->Open Network Stream->
udp ://@xxx.x.xxx.xxx:5000 to watch stream. After some seconds, the timer that located bottom left of VLC starts to increase but there are no frames in screen, just VLC icon.

  


  I checked firewall rules, opened all ports to UDP connections. I am using my IP address to send frames and watch them.
Also, I tried other video codecs like h264, hvec, mpeg4, rawvideo.
Additionally, I tried to watch stream by using Windows Media Player but it didn't work.

  


  What should I do to fix this issue ?

  


• Quickest and most reliable way to get clips of h.264 video from VLC saved uncompressed

  24 janvier 2020, par Stonecraft

  I am trying to set up a pipeline to record video clips while I watch movies (usually but not always in h.264) and prepare them for editing in Premier. I usually watch videos using VLC, and the "record" button is perfect. However, in order to edit the video, it needs to be in a format other than h.264.

  I’ve had variable luck with transcoding.. it seems that I have to use trial and error to find a codec I can convert to that doesn’t result in horrible artifacts. I’m thinking it would be best to decode the video and save in an uncompressed format, then edit, and then encode in the codec of my choice.

  Is there a way for ffmpeg/handbrake to decompress video and then save the uncompressed video instead of transcoding to a different codec ? Or better yet, to get VLC’s "record" button to save the decoded stream instead of the encoded video ?

• FFmpeg : How to convert vertical video with black sides, to video 16:9, with blurred background sides

  10 avril 2017, par Andrey

  

  How to make this by using FFmpeg ?

  Example without FFmpeg :
  Adobe After Effects
  Sony Vegas Pro