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• use ffmpeg to add audio/video sequences from multiple other files in another file

  9 novembre 2015, par robert paré

  I have several mp4 files that contain video and audio content ("base" videos)

  I have a length value (recordingLength) in which the output video should be (let’s say 3600 seconds).

  What I’m trying, is first creating a blank file with the total length (recordingLength) of 3600 seconds. I do it like so :

  ffmpeg -f lavfi -i anullsrc -t 3600 -c:a libfdk_aac ./output.mp4

  Then let’s say I have 5 base videos each lasting a couple of minutes, I need to add each of them at a specific time in the blank file created above. I tried playing around with -itsoffset {seconds} -t {seconds} but I’m still really just playing around trying to get my head around all the options.

• How to stream to NestJS if the data is transmitted through a NATS broker ?

  13 août 2023, par О. Войтенко

  I have an rtsp to mpegts streamer (ffmpeg wrapped in Express for publishing) that streams by publish to a NATS Jetstream.

  


  const options =
     [
         "-rtsp_transport", "tcp",
         "-i", streamUrl,
         '-f', 'mpegts',
         '-pix_fmt', 'yuv420p',
         '-c:v', 'h264',
         '-b:v', '800k',
         '-r', '30',
         '-muxdelay', '0.4',
         '-movflags', 'frag_keyframe+empty_moov',
         '-'
     ];


  


  try {
         const natsConnection = await nats.connect({
             servers: 'ws://127.0.0.1:9222',
             preserveBuffers: true
         })

         conststream = spawn('ffmpeg', options);

         stream.stdout.on('data', (chunk) => {
             console log(chunk);
             natsConnection.publish('stream.1', chunk);
         });

         stream.stdout.on('error', (error) => {
             console.error('FFmpeg error:', error);
         });

         stream.stdout.on('close', (code) => {
             console.log('FFmpeg process closed with code:', code);
         });
     } catch (e) {
         console.error(e);
     }


  


  It's all about the NestJS application signing up for this when the visitor follows the route.
The controller method itself

  


  @get()
   async findOne(
     @Headers() headers,
     @Res() res,
   ) {
     const streamObservable = this.natsService.subscribeStreamEvents('1');

     // Set appropriate headers for video streaming
     res.setHeader('Content-Type', 'video/mp4');
     res.setHeader('Transfer-Encoding', 'chunked');

     res.status(200);

     // Write data chunks directly to the response
     const subscription = streamObservable.subscribe({
       next: (chunk) => {
         console.log('wwww', chunk);
         res.write(chunk);
       },
       error: (error) => {
         console.error('Error streaming video:', error);
       },
       complete: () => {
         res end();
       },
     });

     res.on('close', () => {
       subscription.unsubscribe();
     });
   }


  


  Well, and service service

  


  subscribeToCameraEvents(cameraId: string) {&#xA;     const subject = new Subject<any>();&#xA;&#xA;     this.natsConnection.subscribe(`stream.${cameraId}`, {&#xA;       callback: (err, msg: Msg) => {&#xA;         if (err) {&#xA;           subject.error(err);&#xA;           return;&#xA;         }&#xA;         // console.log(msg.data);&#xA;         subject.next(msg.data);&#xA;       },&#xA;     });&#xA;&#xA;     return subject.asObservable();&#xA;   }&#xA;</any>

  


  The data is consoled as a Buffer.

  


  trying to play the stream

  


  &#xA;&#xA;&#xA;     &#xA;&#xA;&#xA;<video controls="controls" width="640" height="480" style="background: black">&#xA;     <source src="http://localhost:3301/api/streams" type="video/mp4">&#xA;     Your browser does not support the video tag.&#xA;</source></video>&#xA;&#xA;&#xA;

  


  the route is true in the source.

  


  The problem is that through VLC and ffplay - localhost:3301/api/streams the stream is displayed, and everything works fine, without any additional settings.

  


  And here in html does not want.

  


  **What am I doing wrong ? **

  


  I will be glad to any comments and additional questions.

  


  I have tried canvas and jsmpeg (not working too), @Res(passthrough : true) - stream does not work in VLC, ffplay and html (without passthrough stream is working only in VLS and ffplay)

  


• avcodec/mpegvideo : flip motion vector visualization for backward motion vectors

  9 juillet 2014, par Michael Niedermayer

  avcodec/mpegvideo : flip motion vector visualization for backward motion vectors
  Also support changing arrow head/tail shape
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/mpegvideo.c