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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 ?

  


• Gstreamer convert and display video v4l2 - tee problems in rust

  27 mars 2023, par d3im

  I have USB grabber v4l2 source and I want to tee stream to autovideosink and x264enc to file (now as fake black hole)

  


  When I disable one or another branch it works but together Pipeline goes :

  


  Pipeline state changed from Null to Ready
Pipeline state changed from Ready to Paused


  


  and stays there never switches to Playing

  


  gst-launch-1.0 with similar functionality works well.

  


      gst::Element::link_many(&[&pw_video, &v_caps, &vid_queuey, &vid_tee]).unwrap();
    gst::Element::link_many(&[&vid_queue1, &autovideoconvert, &vid_queuex, &autovideosink]).unwrap();
    gst::Element::link_many(&[&vid_queue2, &autovideoconvert_x264, &vid_queue3, &x264, &vid_queue4, &fake]).unwrap();

    let tee_display_pad = vid_tee.request_pad_simple("src_10").unwrap();
    let vid_queue1_pad = vid_queue1.static_pad("sink").unwrap();

    tee_display_pad.link(&vid_queue1_pad).unwrap();

    let tee_convert_pad = vid_tee.request_pad_simple("src_20").unwrap();
    let vid_queue2_pad = vid_queue2.static_pad("sink").unwrap();

    tee_convert_pad.link(&vid_queue2_pad).unwrap();


  


  How can I use tee in rust properly to have playable pipeline with two branches ?

  


  Update : I read some posts about increasing queue size, so I tried for this and then all queues :

  


      let vid_queue1 = gst::ElementFactory::make("queue")
        .name("queue1")
        .property("max-size-buffers", 5000 as u32)
        .property("max-size-bytes", 1048576000 as u32)
        .property("max-size-time", 60000000000 as u64)
        .build()
        .expect("queue1");


  


  but it didn't help so I tried set zero latency :

  


      let x264 = gst::ElementFactory::make("x264enc")
        .name("x264")
        .property_from_str("speed-preset", "ultrafast")
        .property_from_str("pass", "qual")
        .property_from_str("tune", "zerolatency")
        .property("quantizer", 0 as u32)
        .property("threads", 8 as u32)
        .build()
        .expect("!x264");


  


  and it works now. But comparable gst-launch-1.0 settings didn't had such option - only queues sizes increased.

  


  Is there any other option than setting zerolatency ?

  


• Parse dynamic mpd file with Media Source Extensions

  17 février 2023, par FrankC

  I just started learning about adaptive streaming, and currently I'm working on a project that needs showing a live video. In order to control some of the elements in mpd file, I determined to use MSE instead of dash.js. I refer to the code at the following URL :https://learn.microsoft.com/en-us/previous-versions/windows/internet-explorer/ie-developer/samples/dn551368(v=vs.85)
But I found out that there is no "Initialization" tag or "range" attribute in my mpd file. I don't find any relative attribute as well. By the way I'm use nginx-rtmp + ffmpeg to generate dash file.
So here is my dash file looks like

  


  &lt;?xml version="1.0"?>&#xA; &#xA;  <period start="PT0S">&#xA;    &#xA;      &#xA;        &#xA;          <segmenttimeline>&#xA;             <s t="0" d="10000"></s>&#xA;             <s t="10000" d="10000"></s>&#xA;             <s t="20000" d="5000"></s>&#xA;             <s t="25000" d="10000"></s>&#xA;          </segmenttimeline>&#xA;        &#xA;      &#xA;    &#xA;  </period>&#xA;&#xA;

  


  My question is :
1.Did I have any missing parameters in using ffmpeg or nginx-rtmp resulting in losting tag in mpd file ?
2.Or there is other way to setup "Initialization"/"range" attribute and let my program work ?
3.I also curious about why my mpd file doesn't have a baseURL element ?

  


  ※My mpd file works fine with dash.js, I can see the video properly

  


  THANKS A LOT