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• movenc : Allow writing a DASH sidx atom at the start of files

  21 octobre 2014, par Martin Storsjö

  movenc : Allow writing a DASH sidx atom at the start of files
  This is mapped to the faststart flag (which in this case
  
  perhaps should be called "shift and write index at the
  
  start of the file"), which for fragmented files will
  
  write a sidx index at the start.
  When segmenting DASH into files, there’s usually one sidx
  
  at the start of each segment (although it’s not clear to me
  
  whether that actually is necessary). When storing all of it
  
  in one file, the MPD doesn’t necessarily need to describe
  
  the individual segments, but the offsets of the fragments can be
  
  fetched from one large sidx atom at the start of the file. This
  
  allows creating files for the DASH ISO BMFF on-demand profile.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/movenc.c
  • [DH] libavformat/movenc.h

• MP4 moof fragment headers

  23 juillet 2019, par Ariana

  I have a MP4 parser software that get’s a fragmented .mp4 video, parses the MOOV and fragment headers and streams it. I have generated a .mp4 file myself using FFMPEG and MP4Box/bento4, but the software has problems processing it.

  ffmpeg -i input.mp4 -g 25 -c:v libx264 -c:a copy out1.mp4
  
  
  
  mp4fragment out1.mp4 --fragment-duration 1000 --track 'video' output.mp4

  Using the MP4 Explorer software, I noticed in my generated .mp4 file, for all moof.traf.trun, sample duration is set to 0, but in the Track Fragment Header box, it sets the default_sample_duration to 512. While in the another .mp4 file which works fine, there is no default_sample_duration field, but each individual sample has a duration of size 512. Looks like this might cause the problem. The right figure shows the working mp4, and the left one is my generated mp4.

  Is this an update in the newer versions of FFMPEG (or MP4Box or bento4) ? Is there any ways to force setting the sample duration in samples ?

  My .mp4 file

  The working .mp4 file

  

• lavf/matroskaenc : use mkv_check_tag_name consistently

  6 septembre 2016, par Rodger Combs

  lavf/matroskaenc : use mkv_check_tag_name consistently
  Previously, we used a different list of checks when deciding whether to
  
  write a set of tags at all than we did when deciding whether to write an
  
  individual tag in the set. This resulted in sometimes writing an empty
  
  tag master and seekhead. Now we use mkv_check_tag_name everywhere, so
  
  if a dictionary is entirely composed of tags we skip, we don’t write a
  
  tag master at all.
  This affected the test file, since "language" was on one list but not
  
  the other, so we were writing an empty tag master there. The test hash
  
  is updated to reflect that change.
  

  • [DH] libavformat/matroskaenc.c
  • [DH] tests/fate/matroska.mak