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• movenc : Allow writing timed ID3 metadata

  17 janvier 2024, par Martin Storsjö

  movenc : Allow writing timed ID3 metadata
  This is based on a spec at https://aomediacodec.github.io/id3-emsg/,
  
  further based on ISO/IEC 23009-1:2019.
  Within libavformat, timed ID3 metadata (already supported by the
  
  mpegts demuxer and muxer) is handled as a separate data AVStream
  
  with codec type AV_CODEC_ID_TIMED_ID3. However, it doesn't
  
  have a corresponding track in the mov file - instead, these events
  
  are written as separate toplevel 'emsg' boxes.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/movenc.c
  • [DH] libavformat/tests/movenc.c
  • [DH] tests/ref/fate/movenc

• avformat/movenc : Add loop parameter to animated AVIF

  12 janvier 2023, par Vignesh Venkatasubramanian

  avformat/movenc : Add loop parameter to animated AVIF
  The HEIF specification permits specifying the looping behavior of
  
  animated sequences by using the EditList (elst) box. The track
  
  duration will be set to the total duration of all the loops (or
  
  infinite) and the duration of a single loop will be set in the edit
  
  list box.
  The default behavior is to loop infinitely.
  Compliance verification :
  
  * This was added in libavif recently [1] and the files produced by
  
    ffmpeg after this change have EditList boxes similar to the ones
  
    produced by libavif (and avifdec is able to parse the loop count as
  
    intended).
  
  * ComplianceWarden is ok with the produced files.
  
  * Chrome is able to play back the produced files.
  [1] https://github.com/AOMediaCodec/libavif/commit/4d2776a3af53ae1aefdaed463b75ba12fd9cf8c2
  Signed-off-by : Vignesh Venkatasubramanian <vigneshv@google.com>
  
  Signed-off-by : Zhao Zhili <zhilizhao@tencent.com>
  

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

• Generate MPEG-DASH segments when requested [closed]

  16 septembre 2024, par John Smith

  Up front disclaimer : this question is almost identical to the one here : Generate single MPEG-Dash segment with ffmpeg but it seems that ffmpeg has updated over time and now the answer provided by Coumeu is no longer accurate.

  


  Using ffmpeg, I am attempting to "lazily create" the segments needed for MPEG DASH playback. I have a static manifest (MPD) which includes SegmentTemplates for 1 video and 1 audio stream.

  


  Only when the endpoints provided in the SegmentTemplate for init or media segments is hit it will generate this segment. In other words, nothing is processed up front.

  


  I am creating the init segment using the following movflags :

  


  +frag_keyframe+faststart+skip_trailer 


  


  I am creating the media segment using the following movflags

  


  +frag_keyframe+default_base_moof+delay_moov+skip_trailer+dash+global_sidx


  


  and the following additional commands any segment type :

  


  -map_metadata -1 -copyts -start_at_zero -map 0:${streamIndex}


  


  This results in playable video with the correct duration, but it seems to be switching fragments quite fast. On average one fragment per second. When I omit the delay_moov flag, the video also starts glitching, like it's stepping over I-Frames.

  


  My observations when I look at the boxes :

  


  

  • earliest_presentation_time (sidx box) is 0 for all segments

  


  • base_media_decode_time (moof->traf->tfdt box) is 0 for all segments

  


  


  I'm looking for either the correct command line to create segments on the fly, or hacky ways to get it done right if ffmpeg doesn't provide it out of the box. Even information about what to look for would be helpful, because my knowledge about mp4 and MPEG-DASH is running out.