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• Create fragmented MP4 from MP3

  25 octobre 2020, par Stefan Falk

  I am trying to convert an MP3 file to a fragmented MP4 like this :

  


  ffmpeg -i input.mp3 -strict experimental -acodec aac -b:a 256k -f mp4 \
       -movflags faststart+frag_keyframe+empty_moov+separate_moof output.mp4 


  


  However, using Bento4 I can see that there is just one giant mdat object instead of a series of those :

  


  [ftyp] size=8+24
  major_brand = isom
  minor_version = 200
  compatible_brand = isom
  compatible_brand = iso2
  compatible_brand = iso6
  compatible_brand = mp41
[moov] size=8+701
  ...
[moof] size=8+62364
  ...
[mdat] size=8+5794679
[mfra] size=8+59
  [tfra] size=12+31, version=1
    track_ID = 1
    length_size_of_traf_num = 0
    length_size_of_trun_num = 0
    length_size_of_sample_num = 0
  [mfro] size=12+4
    mfra_size = 67


  


  I think what I want is this :

  


  

  


  (source)

  


  But I can't seem to be able to get this from ffmpeg.

  


  I found some other options here like

  


  $ ffmpeg -h muxer=ismv&#xA;...&#xA;-frag_duration     <int>   E.... Maximum fragment duration&#xA;-min_frag_duration <int>   E.... Minimum fragment duration&#xA;-frag_size         <int>   E.... Maximum fragment size&#xA;</int></int></int>

  


  but playing around with these didn't change the output.

  


  How can I create fragments of a specific sice e.g. 5 seconds each ?

  


• ffmpeg options that work with Chrome

  21 avril 2015, par James

  I am trying to find the magic options that make mp4 work in Chrome. I think my videos were working, but don’t seem to any more after Chrome updated.

  Chrome, Version 41.0.2272.101 (Windows)

  I tried some other machines and found some of the videos worked on older versions, and my Mac seems to still work on the latest Chrome.

  I am using the ffmpeg options to convert from png series,

  ffmpeg -framerate 10 -i dance%02d.png  -r 10 -pix_fmt yuv420p dance.mp4

  Some videos work, some don’t, some work some of the time, or stop half way through.

  I tried various other options like,

  ffmpeg -start_number 16 -framerate 10 -i dance%02d.png -r 10 -an -s hd720 \
  
  -vcodec libx264 -pix_fmt yuv420p -preset slow -profile:v baseline \
  
  -movflags faststart -y dance.mp4

  but this just seemed to make things worse.

  here is one of the videos,
  http://www.botlibre.com/media/a786625.mp4

  and another one,
  http://www.botlibre.com/media/a812450.mp4

  Firefox seems to work no problem, on any version, grey background though.
  IE works fine, white background.
  Safari works, grey background.

  Another thing, they videos used to have white background on older Chrome version, but now are grey, except on Mac still white.

  and one more thing. Webm format works, but anyone know the option to remove transparency ? I’m using,

  ffmpeg -i dance%02d.png  -r 10 -c:v libvpx -crf 10 -b:v 512k -c:a libvorbis dance.webm

  just want a solid white background.

• H264 encoder settings

  30 novembre 2011, par Chris Robinson

  I'm using xuggler to encode a series of images to an MP4 file. I use the following code to setup the IStreamCoder and specify the H264 codec :

  // only set if codec is H264
  
  Configuration.configure("/usr/local/xuggler/share/ffmpeg/libx264-hq.ffpreset",
  
              outStreamCoder);
  
  
  
  outStreamCoder.setNumPicturesInGroupOfPictures(12);
  
  outStreamCoder.setCodec(codec);
  
  outStreamCoder.setBitRate(videoSettings.getBitrate());
  
  outStreamCoder.setBitRateTolerance(videoSettings.getBitrateTolerance());
  
  outStreamCoder.setPixelType(IPixelFormat.Type.YUV420P);
  
  outStreamCoder.setHeight(videoSettings.getResolution().height);
  
  outStreamCoder.setWidth(videoSettings.getResolution().width);
  
  outStreamCoder.setFlag(IStreamCoder.Flags.FLAG_QSCALE, true);
  
  outStreamCoder.setGlobalQuality(0);
  
  fps = IRational.make((int) videoSettings.getFramerate(), 1);
  
  outStreamCoder.setFrameRate(fps);
  
  outStreamCoder.setTimeBase(IRational.make(fps.getDenominator(), fps.getNumerator()));

  which yields the following output :

  Codec: CODEC_ID_H264
  
  Resolution: 1280x720
  
  Bitrate: 25000
  
  Bitrate Tolerance: 1000
  
  Framerate: 25.0

  

  Now when I specify the MPEG4 codec, I get the following output :

  Codec: CODEC_ID_MPEG4
  
  Resolution: 1280x720
  
  Bitrate: 25000
  
  Bitrate Tolerance: 1000
  
  Framerate: 25.0

  

  As you can see, the only difference is the ICodec type (MPEG4 instead of H264) and the use of the preset (which is required by xuggler when using an H264 codec). Can anyone explain to me the huge difference in quality and tell me how to resolve the issue ?