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• avcodec/hevc : fix duplicate/wrong nal unit check and difference to openhevc_upstream

  20 octobre 2013, par Mickaël Raulet

  avcodec/hevc : fix duplicate/wrong nal unit check and difference to openhevc_upstream
  NAL_BLA_W_RADL instead of NAL_BLA_N_LP
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/hevc.c

• ffmpeg AAC audio encoding with libfdk_aac : difference between -q:a and -vbr quality parameters ?

  16 juin 2020, par RocketNuts

  I want to encode an audio file to AAC, using libfdk_aac, and I'm wondering about the quality parameters. I want to use variable bitrate encoding, not constant bitrate.

  



  It seems I can specify the quality either with the -vbr N parameter (with N=1..5) like this :

  



  ffmpeg -i input.flac -acodec libfdk_aac -vbr 4 output.m4a


  



  Or using the -q:a N parameter (here N=0..9) like this :

  



  ffmpeg -i input.flac -acodec libfdk_aac -q:a 7 output.m4a


  



  How are these two related, is there a substantial difference ? Do specific -q:a values correspond to certain -vbr values, or is it a different encoding approach altogether ?

  


• What is the difference between these 2 videos ?

  8 octobre 2018, par 98mprice

  I am using fluent-ffmpeg to resize a video.

  I can’t figure out what’s happening though. I have 2 video files, one works but the other doesn’t. I’ve been scouring the mediainfo outputs of both files, checking for discrepancies but other than filesize, duration etc. there’s no difference (same codec, format, width/height, frame rate etc)

  Here’s a link to both files.

  I’ve been reading these video files into fluent-ffmpeg using an input stream, as so :

  await new Promise((resolve, reject) => {
  
      ffmpeg(file.stream)
  
        .output(path)
  
        .size('426x240')
  
        .on('start', function() {
  
            console.log('started');
  
        })
  
        .on('error', function(err) {
  
            console.log('An error occurred: ' + err.message);
  
        })
  
        .on('progress', function(progress) {
  
            console.log('... frames: ' + progress.frames);
  
        })
  
        .on('end', function() {
  
          console.log('Finished processing');
  
          resolve();
  
        })
  
        .run();
  
  });

  The working file prints :

  started
  
  ... frames: 86
  
  ... frames: 107
  
  Finished processing

  But the non-working file doesn’t seem to have any frames, and prints :

  started
  
  ... frames: 0
  
  Finished processing

  Any idea what could be wrong ?

  The ffmpeg command being executed :

  ffmpeg -i pipe:0 -y -filter:v scale=w=426:h=240 uploads/works.mp4