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• Mux segmented mpegts audio and video to single clip with error correction

  16 janvier 2023, par senyacap

  I have a recording as a collection of files in mpegts format, like

  


  audio: a-1.ts, a-2.ts, a-3.ts, a-4.ts 
video: v-1.ts, v-2.ts, v-3.ts


  


  I need to make a single video clip in mp4 or mkv format.

  


  However, there are two problems :

  


  


  1. audio and video segments have different duration each, number of audio segments is different from number of video segments. Total duration of audio and video matches. Hence I can not concat pairwise audio video segments using mpeg and merge them afterwards, I get sync issues increasing progressively

     


  


  2. few segments are corrupt or missing. So if I concat audio and video streams separately using ffmpeg I get streams of different lengths. When I merge these streams using ffmpeg I have correct a/v synchronization until time when first missing packet is encountered.

     


  


  


  It's OK if video freezes for a while or there is silence for a while as long as most of the video is in sync with audio.

  


  I've checked with tsduck and PCR seems to be present in all audio and video segments yet I could not find a way to merge streams using mpegTS PCR as sync reference. Please advise how can I achieve this.

  


• How to "filter" a file through command line before apache sends it to client ?

  1er septembre 2020, par Timothe Jahan

  I have large collection of video files which are available on our website.
For each video we have multiple quality and language, so in order to save space we store only 1 file, which contains all audio and video tracks.

  


  Our streaming server can handle these multitrack files in order to serve only the useful part to each user, but we also make them available for download through the apache web server.
Currently, when a user request a file (certain quality, certain language), we first create a temporary file with only his needs, and give him for download.
I would like to remove this intermediate step and extract on the fly.
Extraction can be done by ffmpeg, but I need to have apache "pipe" the file through ffmpeg before sending the bytes out. Do you have any way of doing this.

  


  example :

  


  


  Filename_multi.mp4 [SD,HD,fr,en,ru]
User request : Filename_HD_fr.mp4 [HD,fr]
Apache fetch the file Filename_multi.mp4 and pipe it through an ffmpeg command and send the bytes as > they are encoded, not waiting for the end.

  


  


  Note this is on linux, and the ffmpeg part is not a problem.

  


  Thx
Timothé

  


• How to detect added scenes in Director's Cut Edition of movie ?

  17 juillet 2019, par B Lolo

  I’ve got huge collection of .mkv files. In every movie folder there are two files : one original movie and one extended edition of that movie.

  Two files can be different for example one is 480p and the second 1080p.

  One can be 1 hour long, second one 40 minutes.

  In those extended edition files scenes are added randomly, so it could be 2 minutes in beginning, 5 minutes after first 10 minutes of the film and so on.

  Is there a way to use Python and ffmpeg to detect scenes from extended edition files that are absent in original movie file ?

  I can also work with only audio if that is easier to do.

  For now I got idea to use ffmpeg and scene detection, I can manually search for differences between files, but I would like some hints where to look changes.

  This is python code with ffmpy library :

  from ffmpy import FFmpeg
  
  
  
  plik = "C:/special.mkv"
  
  png = re.sub("\.mkv","_changes.png",plik)
  
  
  
  ff = FFmpeg(executable='C:/ffmpeg.exe', global_options ='-v error', inputs={plik : ''}, outputs={png : "-vf select='gt(scene\,0.4)',scale=320:-1,tile=10x80 -frames:v 1 -y"})
  
  result = ff.run(stdout=PIPE, stderr=PIPE)