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• ffmpeg audio/video sync problems when uploading to WhatsApp

  11 janvier 2021, par Luke Collins

  (Note : I have looked at related questions such as this one, but the solutions there didn't work for me since presumably their output files wouldn't play correctly in mpv, whereas mine do.)

  


  I want to send a scene from a film to my friend on WhatsApp. I run

  


  


  ffmpeg -i film.mp4 -ss 00:25:30 -t 00:03:00 -c: copy out.mp4

  


  


  to extract the clip, which produces the file out.mp4 which plays fine when I play it with mpv.

  


  If instead, I play the file in my browser (firefox), the first frame is static for a couple of seconds while audio plays, until the video starts and the video and audio are both in sync. (In other words, it seems the file has additional unnecessary audio information appended to the beginning of the file, which starts before my desired clip when played in firefox).

  


  Diagrammatically, I suspect the video contains the following information :

  


  

  


  and firefox plays it in this way :

  


  

  


  What's worse is that when I upload it to WhatsApp, it misaligns the audio with the video, instead playing it this way :

  


  

  


  How can I fix this so that the video has no additional video/audio information ?

  


  I appreciate any help with this.

  


• avcodec/vc1 : change to using v->block instead of s->block for P frames

  23 avril 2018, par Jerome Borsboom

  avcodec/vc1 : change to using v->block instead of s->block for P frames
  The new overlap smooting filter smoothes image pixels stored in v->block.
  
  Switch to v->block instead of s->block for storing decoded image pixels for P
  
  frames. Additionally, we must take incrementing *_blk_idx out of the
  
  vc1_put_signed_blocks_clamped function.
  Signed-off-by : Jerome Borsboom <jerome.borsboom@carpalis.nl>
  

  • [DH] libavcodec/vc1_block.c

• ffmpeg encoded video has video/audio sync delay when uploading to Facebook & WhatsApp

  13 décembre 2019, par royherma

      "fluent-ffmpeg": "^2.1.2",
  
      "ffmpeg": "^0.0.4",
  
      node : 8

  Code to reproduce

  let command = ffmpeg()
  
          .input(tempFilePath)
  
          .input(watermarkFilePath)
  
          .complexFilter([
  
              "[0:v][1:v]overlay=W-w-20:H-h-20"
  
          ])
  
          .videoBitrate(2500)
  
          .videoCodec('libx264')
  
          .audioCodec('aac')
  
          .format('mp4')
  
          .output(targetTempFilePath)

  When applying the ffmpeg encoding command on the attached video, it plays fine on a local device - the issue however is when uploading to Facebook/WhatsApp the audio/video becomes out of sync

  Any ideas on what i need to change in terms of the video/audio settings so that the audio + video are in sync, even when uploaded to the various social networks ?

  Here’s a link to the 3 video files (original, post ffmpeg, post whatsapp upload that includes delay) if you want to get a better idea !

  https://wetransfer.com/downloads/445dfaf0f323a73c56201b818dc0267b20191213052112/24e635

  Thank you and appreciate any help !!