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• Standardized "Skip Intro" in MP4 video files ?

  25 mai 2020, par Crissov

  Is there a standardized way to mark up specific parts of a MP4-contained video as skippable, e.g. trailers, recaps, intros/outros, opening/closing credits, in the metadata in the file itself ? If possible, I would like to set this with FFmpeg or MP4box.

  



  I know that the mvhd box in MOV files makes it possible to specify a single preview. 
I assume Netflix and the like use specially named or hinted chapters, either from file-internal metadata or from a central database, to provide this feature. 
I want to add this now to videos in my personal library, just in case Kodi, VLC or other players and media centers add support for this feature.

  



  Edit List Box elst

  



  As mentioned in the first comment, Edit Lists may be a solution. They are specified in section 8.6.6 of ISO/IEC 14496-12:2015 (ISOBMFF), which I partially cite below.

  



  moov > trak+ > edts ? > elst*

  



  


  [elst] contains an explicit time-line map. 
 Each entry defines part of the track time-line :
  
 by mapping part of the media time-line,
  
 or by indicating ‘empty’ time,
  
 or by defining a ‘dwell’, where a single time-point in the media is held for a period.

  
 


  

  • version is an integer that specifies the version of this box (0 or 1)

  


  • entry_count is an integer that gives the number of entries in the following table

  


  • segment_duration is an integer that specifies the duration of this edit segment in units of the timescale in the Movie Header Box

  


  • media_time is an integer containing the starting time within the media of this edit segment (in media time scale units, in composition time). If this field is set to –1, it is an empty edit. The last edit in a track shall never be an empty edit. Any difference between the duration in the Movie Header Box, and the track’s duration is expressed as an implicit empty edit at the end.

  


  • media_rate specifies the relative rate at which to play the media corresponding to this edit segment. If this value is 0, then the edit is specifying a ‘dwell’ : the media at media-time is presented for the segment-duration. Otherwise this field shall contain the value 1.

  


  


  


• Live streaming multiple bitrates with FFmpeg and node.js

  14 juillet 2014, par user2757842

  I am looking for an efficient way of transcoding a live stream and breaking it up into different bit rates, I have it working as of now but I have to state each time which video I would like to address as well as each different bit rate, example below :

  var spawn = require('child_process').spawn;
  
  
  
  /*
  
  var ffmpeg = spawn('C:\\Users\\Jay\\Documents\\FFMPEG\\bin\\ffmpeg.exe', [
  
      '-i',
  
      'rtmp://192.168.201.8/livepkgr/livestream2 live=1',
  
      '-movflags',
  
      'isml+frag_keyframe',
  
      '-f',
  
      'ismv',
  
      'http://192.168.201.237/LiveSmoothStreaming.isml/Streams(video2)'
  
  ]);
  
  */
  
  
  
  var ffmpeg = spawn('C:\\Users\\Jay\\Documents\\FFMPEG\\bin\\ffmpeg.exe', [
  
      '-i',
  
      'rtmp://192.168.201.8/livepkgr/livestream live=1',
  
      '-ac',
  
      '2',
  
      '-b:a',
  
      '64k',
  
      '-c:v',
  
      'libx264',
  
      '-b:v:0',
  
      '150k' /* first bit rate i want */ ,
  
      '-movflags',
  
      'isml+frag_keyframe',
  
      '-f',
  
      'ismv',
  
      'http://192.168.201.237/LiveSmoothStreaming2.isml/Streams(video1)',
  
      '-c:v',
  
      'libx264',
  
      '-b:v:0',
  
      '500k' /* second bit rate i want */ ,
  
      '-movflags',
  
      'isml+frag_keyframe',
  
      '-f',
  
      'ismv',
  
      'http://192.168.201.237/LiveSmoothStreaming2.isml/Streams(video3)'
  
  ]);

  As you can see, this is not a very efficient way of doing it as this is only for 2 bit rates, I have to give a video name (video1, video 3 etc) each time I want a new bit rate and then I have to give it it’s bit rate (150k, 500k etc). If I wanted anymore bitrates, the code lines would go on and on and it would quickly become messy.

  Has anyone worked within the world of Node.js and FFmpeg that could maybe point me in the direction of managing this more efficiently ? Or even link me to a page which would help me out ?

  Cheers

• Trying to read streaming video using OpenCVSharp4

  7 septembre 2022, par AlvinfromDiaspar

  I'm just not having any luck whatsoever with this.
I'm calling OpenCvSharp.VideoCapture("udp ://0.0.0.0:11111") to try to read a video stream.
This does not work, and the documentation seems like it doesnt support streaming.

  



  I've also tried (without success) trying to grab images using OpenCvSharp, but i've no idea how to do that. Documentation for it doesn't show any indication this is possible as well.

  



  The snippet for this is here :

  



  


          var vc = new OpenCvSharp.VideoCapture("udp://0.0.0.0:11111");

        if (!vc.IsOpened())
        {
            vc.Open("udp://0.0.0.0:11111");
        }

        while (true)
        {
            var matImage = new OpenCvSharp.Mat();
            if (vc.Read(matImage))
            {
                try
                {
                    var bmp = OpenCvSharp.Extensions.BitmapConverter.ToBitmap(matImage);
                    using (var ms = new MemoryStream())
                    {
                        var bmpImg = new BitmapImage();
                        bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
                        bmpImg.StreamSource = ms;
                        this.videoFrameImage.Background = new ImageBrush(bmpImg);
                        this.isReadingVideoStream = true;
                    }
                }
                catch
                {
                    // just swallow exception
                }
            }
        }


  


  



  Before trying OpenCvSharp (which seemed extremely promising), I tried using ffmpeg with mild/partial success. I was able to extra a frame from the real-time streaming video and save it to a file. Unfortunately, the behavior was not consistent. Sometimes it saves images, sometimes it doesn't. And when it does save images it's usually just a handful (even though the video is constantly being streamed).

  



  The command line for this is here :

  



  


  ffmpeg.exe -i udp ://0.0.0.0:11111 -ss 00:00:01 -vframes 1 -q:v 1 -y
 filename.jpg

  


  



  I may go back to trying again with ffmpeg as im getting absolutely nowhere with OpenCvSharp.
Wondering if anybody out there has been successfully implementing with either one of these (or another way) ?

  



  * Update *

  



  I found a set of Nuget packages which does indicate support for streaming video.
The nugets are :

  



  

  • OpenCvSharp4

  


  • OpenCvSharp4.Windows

  


  • OpenCvSharp4.runtime.win

  


  



  But now i am currently facing a run-time error :

  



  Method not found: 'Void OpenCvSharp.VideoCapture..ctor(System.String, OpenCvSharp.VideoCaptureAPIs)'.


  



  Incidentally, i just raised this issue :