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• Capturing snapshot works on one RTSP stream and fails on another

  29 mars 2012, par Saurabh Gandhi

  I am using the VLM feature (over telnet) of VLC to re-stream a live camera RTSP stream using VOD (video on demand). This provides me with two options of viewing the live stream :

  1. Original camera stream
  2. VOD stream generated using VLM

  Both these streams are working fine when viewed within VLC player. I would like to take a snapshot from both these streams whenever the user presses a key. So, I am using command-line vlc interface to grab a snapshot, the command for which is :

  • Snapshot from original camera stream (Case I)

  cvlc -V dummy --video-filter scene --scene-format jpeg --scene-prefix myscene --start-time=0 --stop-time=1 --scene-replace --scene-path /var/www/ <original camera="camera" stream="stream"> vlc://quit;
  
  </original>

  • Snapshot from VOD stream (Case II)

  cvlc -V dummy --video-filter scene --scene-format jpeg --scene-prefix myscene --start-time=0 --stop-time=1 --scene-replace --scene-path /var/www/ <vod stream="stream" generated="generated" using="using" vlm="vlm"> vlc://quit;
  
  </vod>

  Now, case I seems to work fine but case II does not work, in-spite of confirming that both the live streams are working fine. What could be the problem ?

  Here are the logs of VLC when case II is executed on command-line :

  saurabh@saurabh-Latitude-E5510:~/Desktop/html_trial$ cvlc -V dummy --video-filter scene --scene-format jpeg --scene-prefix myscene --start-time=0 --stop-time=1 --scene-replace --scene-path /var/www/ rtsp://10.17.1.150:5544/vid1 vlc://quit; 
  
  
  
  VLC media player 1.1.9 The Luggage (revision exported) 
  
  Blocked: call to unsetenv("DBUS_ACTIVATION_ADDRESS") 
  
  Blocked: call to unsetenv("DBUS_ACTIVATION_BUS_TYPE") 
  
  [0x97c684c] dummy interface: using the dummy interface module... 
  
  rc buffer underflow 
  
  rc buffer underflow 
  
  rc buffer underflow 
  
  rc buffer underflow 
  
  ^C[0x97be2ac] signals interface error: Caught Interrupt signal, exiting...

  Regards,

  Saurabh Gandhi

• Capturing snapshot using vlc

  28 mars 2012, par Saurabh Gandhi

  I am using the VLM feature (over telnet) of VLC to re-stream a live camera RTSP stream using VOD (video on demand). This provides me with two options of viewing the live stream :

  1. Original camera stream
  2. VOD stream generated using VLM

  Both these streams are working fine when viewed within VLC player. I would like to take a snapshot from both these streams whenever the user presses a key. So, I am using command-line vlc interface to grab a snapshot, the command for which is :

  • Snapshot from original camera stream (Case I)

  cvlc -V dummy --video-filter scene --scene-format jpeg --scene-prefix myscene --start-time=0 --stop-time=1 --scene-replace --scene-path /var/www/ <original camera="camera" stream="stream"> vlc://quit;
  
  </original>

  • Snapshot from VOD stream (Case II)

  cvlc -V dummy --video-filter scene --scene-format jpeg --scene-prefix myscene --start-time=0 --stop-time=1 --scene-replace --scene-path /var/www/ <vod stream="stream" generated="generated" using="using" vlm="vlm"> vlc://quit;
  
  </vod>

  Now, case I seems to work fine but case II does not work, in-spite of confirming that both the live streams are working fine. What could be the problem ?

  Here are the logs of VLC when case II is executed on command-line :

  saurabh@saurabh-Latitude-E5510:~/Desktop/html_trial$ cvlc -V dummy --video-filter scene --scene-format jpeg --scene-prefix myscene --start-time=0 --stop-time=1 --scene-replace --scene-path /var/www/ rtsp://10.17.1.150:5544/vid1 vlc://quit; 
  
  
  
  VLC media player 1.1.9 The Luggage (revision exported) 
  
  Blocked: call to unsetenv("DBUS_ACTIVATION_ADDRESS") 
  
  Blocked: call to unsetenv("DBUS_ACTIVATION_BUS_TYPE") 
  
  [0x97c684c] dummy interface: using the dummy interface module... 
  
  rc buffer underflow 
  
  rc buffer underflow 
  
  rc buffer underflow 
  
  rc buffer underflow 
  
  ^C[0x97be2ac] signals interface error: Caught Interrupt signal, exiting...

  Regards,

  Saurabh Gandhi

• Is it possible to use something other than a circular buffer when using ffmpeg to pass RTSP video to a WebRTC client ?

  3 novembre 2024, par Doctico

  I have a Node application that uses ffmpeg to receive the RTSP stream of an ip camera (h264), and then pass send it using node-webrtc to a remote client. However, in my current implementation, ffmpeg only outputs 8192 byte chunks, which must be buffered in order to create the full frame that my current node-webrtc flow expects. This circular buffer results in a 1-2 second delay when the client is viewing the video. Is there any way to pass the stream through node-webrtc as the chunks come in, or at least extract complete frames so that circular buffering is not necessary ?

  


  So far, I have tried this, which works but has a 1-2 second delay, and even higher delay with higher resolution cameras :

  


      async startStream() {

        const rtspUrl = 'rtsp://my-rtsp-url';

        const videoSource = new wrtc.nonstandard.RTCVideoSource();
        const videoTrack = videoSource.createTrack();

        const width = 640;
        const height = 480;
        const frameSize = width * height * 1.5; // YUV420p format

        //circular buffer:
        let frameBuffer = Buffer.alloc(0);
        const frameStream = new Writable({
            write: (chunk, encoding, callback) => {
                frameBuffer = Buffer.concat([frameBuffer, chunk]);

                while (frameBuffer.length >= frameSize) {
                    const frame = frameBuffer.slice(0, frameSize);
                    frameBuffer = frameBuffer.slice(frameSize);

                    videoSource.onFrame({
                        width: width,
                        height: height,
                        data: new Uint8ClampedArray(frame)
                    });
                }
                callback();
            }
        });

        const ffmpegProcess = ffmpeg(rtspUrl)
            .inputOptions([
                `-fflags nobuffer`,
                `-flags low_delay`,
                `-rtsp_transport tcp`,
                `-strict experimental`,
                `-analyzeduration 0`,
                `-threads 0`,
                `-hwaccel auto`
            ])
            .outputOptions([
                `-f rawvideo`,
                `-c:v rawvideo`,
                '-b:v', streamId === 1 ? '2000k' : '1000k',
                '-bf', '0',
                `-s ${width}x${height}`,
                `-pix_fmt yuv420p`,
                `-tune zerolatency`
            ])
            .on('start', (cmd) => console.log('FFmpeg started:', cmd))
            .on('error', error => {
                console.error('FFmpeg error:', error);
                this.stopStream();
            })
            .on('end', () => {
                console.log('FFmpeg stream ended');
                this.stopStream();
            })

        ffmpegProcess
            .pipe(frameStream);

        return videoTrack;
    }