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• dashenc : Use pts for MPD timeline timestamps

  17 novembre 2014, par Martin Storsjö

  dashenc : Use pts for MPD timeline timestamps
  This should be more correct. This also should give more sensible
  
  switching between video streams with different amount of b-frame
  
  delay.
  The current dash.js release (1.2.0) fails to start playback of
  
  such files from the start (if the start pts is > 0), but this has
  
  been fixed in the current git version of dash.js.
  Also enable the use of edit lists, so that streams in many cases
  
  start at pts=0.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavformat/dashenc.c

• avformat/dashdec : Ensure strings are zero-terminated

  2 mars 2021, par Andreas Rheinhardt

  avformat/dashdec : Ensure strings are zero-terminated
  strncpy only ensures that one does not write beyond the end of the
  
  destination buffer ; in case of truncation it does not zero-terminate
  
  the destination buffer. This makes using it the way it is now in the
  
  DASH demuxer dangerous. So use av_strlcpy instead.
  Also don't write anything if there is no id : The buffer has already been
  
  zeroed initially.
  The DASH testset from the Universität Klagenfurt contains samples with
  
  ids that are too long. E.g.
  
  http://ftp.itec.aau.at/datasets/DASHDataset2014/TearsOfSteel/1sec/TearsOfSteel_1s_simple_2014_05_09.mpd
  Reviewed-by : Steven Liu <lq@chinaffmpeg.org>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/dashdec.c

• Why are there multiple timescale specified in a MP4/AVC container file ?

  24 juin 2021, par Lexx32117

  I am currently parsing a MPEG-DASH stream initialization segment (generated by FFMPEG) and I noticed that the timescale is specified at multiple different places in my file :

  


  

  • In the movie header box (mvhd) : 1000

  


  • In the media header box of my video track (mdhd) : 15360

  


  • In the AVC Configuration box (avcC) more precisely in the VUI section of the sequence parameter set NAL unit : 60

  


  


  Why is it specified in so many different places ? Why do they have different values ? Is there a hierarchy in these value ? For example does 60 overrides 15360 and 15360 overrides 1000 ?

  


  Here's the command I used to generate the file I am looking at :

  


  ffmpeg -f v4l2 -pixel_format yuyv422 -vcodec rawvideo -framerate 30 -video_size 640x360 -i /dev/video0 \
        -f dash -remove_at_exit false -use_template true -use_timeline true -streaming true -window_size 5 -extra_window_size 5 -seg_duration 5 -vcodec libx264 -b:v 1M -maxrate 1M -bufsize 2M  -pix_fmt yuv420p -r 30 -s 640x360 -aspect 16:9 /var/www/html/media/live.mpd