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• MP4 cut with ffmpeg doesn't play nicely in VLC but does in Browser

  21 février, par Alex

  I cut a video with ffmpeg :

  


  ffmpeg -ss 2 -to 10 -i src.mp4 -c copy out.mp4


  


  But the playback in VLC is choppy for the first few seconds. Strangely it does play in my browser fine.

  


  I saw this post :
https://superuser.com/questions/1167958/video-cut-with-missing-frames-in-ffmpeg?newreg=1502e1698e0344acb214aa8d7e6048bd where the suggestion is to use -avoid_negative_ts make_zero. That does fix the playback in VLC. I think that shifts the whole stream, and results in the video being longer than I want it to be.

  


  For my use case I need the video to be precisely the correct length and I can't incur the cost of a (full) re-encode. I think the addition of -avoid_negative_ts is effectively snapping the cut to the nearest keyframe.

  


  So I think the negative timestamps are upsetting VLC ? I can see they exist.

  


  $ ffprobe -v error -select_streams v:0  -of  default=noprint_wrappers=1 out.mp4 -show_entries packet=pts | head
pts=-30720
pts=-30464
pts=-30208
pts=-29952


  


  I also tried with a few other media players (Films & TV in Windows) and had similar issues. Is there a better way to handle this, in a way that will allow the output video to be played normally ?

  


  I saw the approach in this question : Cut a video in between key frames without re-encoding the full video using ffpmeg ?. But had issues with "Non-monotonous DTS" that also seemed to manifest in choppy playback.

  


• FFMPEG libx264 mp4 file does not play in firefox Windows

  2 mai 2020, par Behel

  Some of my ffmpeg converted videos in mp4 format, using libx264 encoder, aren't playable with Firefox browser on Windows.

  



  Here is my ffmpeg command : 
ffmpeg -i file_tmp.mp4 -c:v libx264 -profile:v baseline -level 3.0 -crf 15 -preset slow -pix_fmt yuv420p -c:a aac -movflags faststart -strict -2 -vf scale=1024:576 file.mp4

  



  The video can be played with every browsers on Mac, and works well with Webkit based browers on Windows.

  



  The problem not occur with every video converted, only a few, like this one for instance : https://attentionphilippelepara.pet/testcard/m6-29_04_2020-mire.mp4

  



  Here is what I see when i try to play this media, on Firefow Windows then on Chrome Windows.

  



  

  



  I really don't see where is the problem. Can someone could help me ?

  


• Revision 47380c3350 : Fix the bug which made VP8 denoiser not bit-exact between C code and SSE code.

  10 septembre 2014, par JackyChen

  Changed Paths :
   Modify /vp8/encoder/denoising.c

  
   Modify /vp9/encoder/vp9_denoiser.c

  
   Modify /vp9/encoder/vp9_denoiser.h

  
  
  Fix the bug which made VP8 denoiser not bit-exact between C code and SSE code.

  This issue is found when the denoising mode is set to kDenoiserOnYUVAggressive.
  Updated the C code to make it the same with SSE version.

  I also changed several lines in VP9 denoiser for the code style.

  Change-Id : I640d48cf946fe8c6a400e6e252107501d1e226d3