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• mjpeg : Move code out of else branch

  29 juin 2013, par Luca Barbato

  mjpeg : Move code out of else branch
  Simplify the control flow and spare some vertical space.
  

  • [DH] libavcodec/mjpegdec.c

• How does Chrome decide how much video to buffer for HTML5 MP4 ?

  5 mars 2015, par user3466413

  I have an MP4 video that is variable bitrate, so the average bitrate doesn’t necessarily stay consistent throughout the entire file. Because my video is a capture of a computer screen, some parts of the video are very low bitrate because nothing is happening, and other parts are a much higher bitrate because there’s a lot of activity on the screen.

  How does Chrome decide how much video to buffer for progressive download HTTP(S) videos ? I’m running into a problem where Chrome tends to buffer too little, so playback stutters.

  If there’s no way of convincing Chrome to download a certain time of video (and I don’t want to just preload the entire thing), can I author the MP4 some special way to solve the problem ? I’m using FFmpeg and MP4Box. Maybe it’s up to the HTTP server ?

• How can I get the final size after transcripting a video to stream it with fluent-ffmpeg ?

  5 avril 2018, par G. Manukyan

  I am trying to stream a video using createReadStream and using pipe(res) in node.js and it works fine if the file doesn’t need transcoding (mp4, webm).

  With mkv files I am using fluent-ffmpeg to transcode it on the fly, but the problem is that I can’t go back and forward in the html video player.

  download = function(file, req, res) {   
  
  
  
      const range = req.headers.range
  
      const parts = range.replace(/bytes=/, "").split("-")
  
  
  
      const start = parseInt(parts[0], 10);
  
      const end = parts[1] ? parseInt(parts[1], 10) : file.length - 1
  
  
  
      res.setHeader('Content-Type', 'video/webm')
  
      res.setHeader('Accept-Ranges', 'bytes');
  
      res.setHeader('Content-Length', 1 + end - start);
  
      res.setHeader('Content-Range', `bytes ${start}-${end}/${file.length}`);
  
      res.statusCode = 206;
  
  
  
      var stream = file.createReadStream({start, end})
  
  
  
      ffmpeg(stream)
  
      .videoCodec('libvpx')
  
      .audioCodec('libvorbis')
  
      .videoBitrate('512k')
  
      .format('webm')
  
      .on('start', () => {
  
          console.log('transcoding...')
  
      })
  
      .on('error', (err, stdout, stderr) => {
  
          console.log(err.message, err, stderr);
  
      })
  
      .on('progress', function(progress) {
  
          console.log(progress);
  
      })
  
      .on('end', function(filenames) {
  
          console.log("Finished transcoding.");           
  
      })
  
      .pipe(res);
  
  
  
  }

  I think that comes from the fact that we don’t know in advance the size of the final transcoded file so the range we send in the headers is wrong and somehow make the video player "limited".

  What can be a workaround to this problem ?