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• qt-faststart - stco offset bug fix

  1er juin 2018, par erankor

  qt-faststart - stco offset bug fix
  when the last offsets in the stco atom are close to 4GB, the addition of
  
  the moov atom size can overflow, causing corruption near the end of the
  
  mp4 file.
  
  this patch upgrades all stco atoms to co64 when such an edge case is
  
  detected. in order to accomplish this, the implementation was changed to
  
  walk the atom tree, instead of searching for the strings 'stco'/'co64'.
  
  this was required since when an stco atom is changed to co64, its size
  
  changes, and the sizes of all containing atoms (moov, trak, etc.) have
  
  to be updated as well.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] tools/qt-faststart.c

• vf_scale_vaapi : Crop input surface to active region

  13 septembre 2016, par Mark Thompson

  vf_scale_vaapi : Crop input surface to active region
  If the input has been decoded from a stream which uses edge cropping
  
  then the whole surface need not be valid.  This defines an input
  
  region for the scaler so we only use the active area of the frame.
  

  • [DBH] libavfilter/vf_scale_vaapi.c

• MSE Does not show duration when MPEG-DASH segments are created with FFmpeg

  15 mars 2023, par WaveLink

  I am trying to create a system that streams DASH segments to the browser, where it gets decoded by Media Source Extensions. When using MP4Box, the init segment loads the duration into the player, but the version generated by FFmpeg does not.

  


  I believe this is due to some sort of header missing from the init segment generated by FFmpeg, but I have not been able to figure it out. Here is the command I use to generate the files :

  


  ffmpeg -i .\source.opus -c:a libopus -c:v none -seg_duration 1 -dash_segment_type mp4 -preset ultrafast -use_timeline 1 -use_template 1 -streaming 1 -init_seg_name "segment_init.mp4" -media_seg_name "segment_$Number$.m4s" -fflags +genpts -f dash ./out.mpd
When using MP4Box, this is the config I use :

  


  MP4Box -dash 1000 -rap -profile live -segment-name "segment_$Number" .\out.mp4
In both cases, the audio does play, and both of them contain similar headers, but the FFmpeg version just does not contain the media duration in the init segment, or at least the MSE implementation cannot read it.

  


  I tested this in Chrome, Firefox, and Edge, and all of them behave the same.

  


  Thanks for any help.