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• Debugging an MP4 opened by VLC but not by ffplay

  15 mai 2017, par MaMazav

  I’m writing a code which creates MP4 files. To check it I’ve created an MP4 file.

  The file is played correctly by VLC and Firefox, but not by ffplay or by Chrome. I guess the file contains error which VLC can cope with but more aggressive MP4 reader cannot.

  I’ve thought about repairing the file and check what are the differences to fix my code. However I tried some programs to repair MP4 files, without success until now.

  Can someone reccommend another way to debug the problem, or a good tool to fix MP4 files ? The file is a fragmented MP4 contains both the init section (ftyp, moov boxes) and one fragment section (moof and empty sidx).

  Here is the video file :

  https://www.dropbox.com/s/rojxzvkfxfj31u8/400k00001-3_serialized.mp4?dl=0

  EDIT : It doesn’t work also in Firefox, when using Media Source Extensions like in this example :
  http://people.mozilla.org/ jyavenard/tests/mse_mp4/paper.html

  (don’t forget to enable MSE on Firefox, as explained here :
  http://www.linuxveda.com/2015/04/02/enable-mse-native-html5-support-firefox-linux/)

  EDIT2 : In chrome ://media-internals, I see the following error with the above example :
  Append : stream parsing failed. Data size=131072 append_window_start=0 append_window_end=inf

  (Change the URL to be the file and change the codec to be ’avc1.4d401f’ instead of ’avc1.64000d,mp4a.40.2’).

• avformat/dovi_isom : Implement Dolby Vision configuration parsing/writing

  1er janvier 2022, par quietvoid

  avformat/dovi_isom : Implement Dolby Vision configuration parsing/writing
  Both parse/write implementations are based on mov/movenc.
  This only adds support for the "Dolby Vision configuration box".
  
  Other configuration boxes, such as
  
  "Dolby Vision enhancement layer configuration box" are not supported.
  The new functions will be used to implement parsing/writing the DOVI config
  
  for Matroska, as well as to refactor both mov/movenc to use dovi_isom functions.
  Signed-off-by : quietvoid <tcChlisop0@gmail.com>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavformat/dovi_isom.c
  • [DH] libavformat/dovi_isom.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.