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• seeking in a file that ffmpeg is processing from a live stream

  8 mai 2024, par Ken Mandelberg

  I'm using ffmpeg to take input from a live stream and write an mkv file. The stream runs a few hours. I want to play the mkv file while this is in progress. I find that the players basically do "seeks" by playing through the file, which is ok for very short "seeks" but not for very long ones.

  


  When the ffmpeg ends it finalizes the mkv file, and seeks long or short work fine.

  


  What can I do to be able to have a more usable mkv while ffmpeg is in progress ? I suppose I could force ffmpeg to create a new mkv file every hour, with a name including an index. (Is there any automation for that ?), but I was hoping for some way to force periodic finalizations to the single file.

  


  This is on Linux.

  


• what is the recommended commands to transcode video for Mpeg dash.

  16 août 2015, par jobin

  I need to transcode videos and add them to Wowza server. I found some articles talk about this but there command not working, I fixed there command. but because it is not my area I feel there is better ffmpeg commands for this task.

  the articles that I uses are :

  • http://blog.streamroot.io/encode-multi-bitrate-videos-mpeg-dash-mse-based-media-players/
  • http://www.wowza.com/forums/content.php?192-Encoding-Suggestions-for-Video-on-Demand

  both of them have issues and they don’t use ’-force_key_frame" option.

  anyway my command is :

  ffmpeg -y -i %inputFile% -s 320x180 -y -strict experimental -acodec aac -ab 64k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -force_key_frames expr:gte(t,n_forced*2)  -b 270000 -threads 64 %outputFile%_400p.mp4
  
  ffmpeg -y -i %inputFile% -s 420x270 -y -strict experimental -acodec aac -ab 64k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -force_key_frames expr:gte(t,n_forced*2) -b 570000 -threads 64 %outputFile%_700p.mp4
  
  ffmpeg -y -i %inputFile% -s 720x406 -y -strict experimental -acodec aac -ab 128k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -force_key_frames expr:gte(t,n_forced*2) -b 1000000 -threads 64 %outputFile%_1100p.mp4
  
  ffmpeg -y -i %inputFile% -s 1024x576 -y -strict experimental -acodec aac -ab 128k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -force_key_frames expr:gte(t,n_forced*2) -b 1200000 -threads 64 %outputFile%_1300p.mp4
  
  ffmpeg -y -i %inputFile% -s 1080x608 -y -strict experimental -acodec aac -ab 128k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -force_key_frames expr:gte(t,n_forced*2) -b 1400000 -threads 64 %outputFile%_1500p.mp4

  is there any recommendation ?

• FFMPEG WAV file not spitting out correct audio length

  7 juin 2018, par Alexander Leon

  I am piping the audio out with the ’attachment’ header so that the result is immediately downloaded. With other formats, such as mp3, the duration on the downloaded file metadata is set correctly. With WAV tho, the duration reads 00:00, which makes it basically unusable by audio players like iTunes. Any help ?

  app.get('/', (req, res) => {
  
      res.contentType('audio/wav');
  
      res.attachment('somefile.wav');
  
      var pathToAudio = 'https://dl.dropbox.com/s/pc7qp4wrf46t9op/test-clip.webm?dl=0';
  
      ffmpeg(pathToAudio)
  
          // .output(stream, {end: true})
  
          .toFormat('wav')
  
          // setup event handlers
  
          .on('error', function(err) {
  
              console.log('an error happened: ' + err.message);
  
          })
  
          .pipe(res {end: true})
  
  });