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• How to fix "corrupted" and/or out of sync MP4s with FFMPEG ? [closed]

  15 juillet 2022, par JoeDohn

  Some videos recorded by our users are corrupted and we have no idea why. They’re MP4s recorded from android, about 5% of videos sent by our users end up +/- unreadable.

  


  When trying to read them on firefox it says the file is corrupt, on chrome we get a black player and the video doesn’t start.

  


  The video can be read with VLC but the audio and video are out of sync. After a re-encoding the video are readable on browsers, but also out of sync : When we open the video, the audio start but the image is frozen for a few seconds, then when the image starts it’s obviously not in sync with the audio since it started too late.

  


  There is this error in the firefox console when trying to play the video :

  


  Media resource https://[……] could not be decoded. 2 […].mp4
Media resource https://[…] could not be decoded,
error: Error Code: NS_ERROR_DOM_MEDIA_DECODE_ERR (0x806e0004)
Details: mozilla::MediaResult mozilla::AppleATDecoder::DecodeSample(mozilla::MediaRawData *): 
Error decoding audio sample: 1650549857 @ 64000[…].mp4


  


  Does anybody have any idea on how to fix those videos ? I tried dozens of ffmpeg commands(with -async 1, trying to convert from VFR to CFR, changing the codec, the extension etc… I have no idea what to try next)

  


  Thanks

  


• Non monotonically increasing dts to muxer in stream

  16 juillet 2020, par Eduardo Preto

  I'm just trying to save same frames on video from a buffer, where I properly saved the Bitmap Frame, and the Time Stamp, of the frame.

  



  writer1 = new VideoFileWriter();
this.writer1.Width = this.videoSourceEndo.VideoResolution.FrameSize.Width;
this.writer1.Height = this.videoSourceEndo.VideoResolution.FrameSize.Height;
this.writer1.VideoCodec = VideoCodec.H264;
this.writer1.BitRate = (this.videoSourceEndo.VideoResolution.FrameSize.Height * this.videoSourceEndo.VideoResolution.FrameSize.Width * 30);

this.writer1.VideoOptions["preset"] = "superfast";
this.writer1.VideoOptions["tune"] = "zerolatency";

writer1.Open("test_HDMI.mp4");


  



  (...)

  



  writer1.WriteVideoFrame(endoFrameBuffer[endoFrameBuffer.Tail],endoFrameBuffer.getframetime(endoFrameBuffer.Tail));


  



  But on visual studio (not on the first frame) I'm getting this error :
Accord.Video.VideoException : 'Error while writing video frame. Error -22 : Invalid argument. See console output for more details.'

  



  And on console :
Application provided invalid, non monotonically increasing dts to muxer in stream 0 : 512 >= 512

  



  I don't know the reason for that because on debug all values seems right.
(Please let me know if you need more code)

  


• Extract image from video in Python using ffmpeg and subprocess

  13 juin 2021, par Mevon

  Me and a friend are currently working on a twitter bot which uploads images taken from randomly chosen video files.
  
We are using ffmpeg, with subprocess.call(), to get out.jpg from a video file,
  
which is working fine when the subtitles are hardcoded into the video.
  
We've also made it burn the subtitles into the out.jpg outside of python, but when trying it inside pyhton with subprocess.call() it won't work and it will say :

  


  Output /file/path/to/file.mkv same as Input #0 - exiting
FFmpeg cannot edit existing files in-place.


  


  This is the code for harcoded subtitles.

  


  subprocess.call(
        ['ffmpeg', '-y', '-ss', str(randomTime), '-i', filepath, '-vframes', '1', '-vf', 'scale=1920:1080', '-q:v', '1',
         '-qmin', '1', tmpfilename])


  


  And this the code for non hardcoded subtitles.

  


  subprocess.call(
        ['ffmpeg', '-y', '-ss', str(randomTime), '-copyts', '-i', filepath, '-vf', 'subtitles', filepath, '-vframes', '1', '-vf', 'scale=1920:1080',
         '-vf', '-q:v', '1', '-qmin', '1', '-frames:v', '1', tmpfilename])


  


  Also both me and my friend are not so sure if calling ffmpeg using subprocess.call() is the right way to do it in python.
  
Any kind of help is welcome and please ask me for more code or more details if needed.