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• FFMPEG no audio in final output [migrated]

  16 juin 2015, par Maverick

  I have the following FFMPEG command working.

  ffmpeg -y -i slide.mp4 -f lavfi -i "color=c=black:s=1920x1080:r=25:d=1" -filter_complex "[0:v] setpts=PTS-STARTPTS [main]; \
  
   [1:v] trim=end=3,setpts=PTS-STARTPTS [pre]; \
  
   [1:v] trim=end=3,setpts=PTS-STARTPTS [post]; \
  
   [pre][main][post] concat=n=3:v=1:a=0 [out]" -map "[out]" output.mp4

  It appends black frames at the start and end of the video. However, the output file does not contain the audio from the input file.

  Any pointers to the problem will be highly appreciated.

• 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 ?

• lavu : remove comma at final enumeration items to fix pedantic warnings

  20 octobre 2016, par Michael Behrisch

  lavu : remove comma at final enumeration items to fix pedantic warnings
  

  • [DH] libavutil/log.h
  • [DH] libavutil/pixfmt.h