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• How to change part of a MKV video with another MKV video without re-encode and without changing audio file of the primary MKV file [closed]

  10 octobre 2020, par MonsterMMORPG

  I have a lecture that I have recorded with using OBS studio and my microphone

  


  But I want to replace certain part of that video with another video without re-encoding or touching the audio

  


  The another video is also recorded with OBS studio with the same settings

  


  If encoding is necessary I accept that as well

  


  So what would be the appropriate ffmpeg command ?

  


  Here example file definitions and durations to give more clear example

  


  


  • a.mkv : 77 minutes long

    


  


  • b.mkv : same format and 2 minutes long

    


  


  • c.mkv : I want to replace 00.23.00 - 00.25.00 part of a.mkv with b.mkv without changing the audio file of a.mkv

    


  


  


  Is this possible without encoding or with re-encoding ?

  


  So can you provide an example code with some definitions

  


  How do we define starting position, the durations ? I found some examples on the Internet but they were not definitive enough

  


  Answer to this question : https://superuser.com/questions/1591877/how-to-change-part-of-a-mkv-video-with-another-mkv-video-without-re-encode-and-w

  


• avformat/aviobuf : discard part of the IO buffer in ffio_ensure_seekback if needed

  28 septembre 2020, par Marton Balint

  avformat/aviobuf : discard part of the IO buffer in ffio_ensure_seekback if needed
  Previously ffio_ensure_seekback never flushed the buffer, so successive
  
  ffio_ensure_seekback calls were all respected. This could eventually cause
  
  unlimited memory and CPU usage if a demuxer called ffio_ensure_seekback on all
  
  it's read data.
  Most demuxers however only rely on being able to seek back till the position of
  
  the last ffio_ensure_seekback call, therefore we change the semantics of
  
  ffio_ensure_seekback so that a new call can invalidate seek guarantees of the
  
  old. In order to support some level of "nested" ffio_ensure_seekback calls, we
  
  document that the function only invalidates the old window (and potentially
  
  discards the already read data from the IO buffer), if the newly requested
  
  window does not fit into the old one.
  This way we limit the memory usage for ffio_ensure_seekback calls requesting
  
  consecutive data windows.
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavformat/avio_internal.h
  • [DH] libavformat/aviobuf.c

• ffmpeg add watermark by output part count (watermark1.png for part 1, ...)

  12 octobre 2020, par Steapy

  I have currently following code (not optimized yet !) :

  


  converter.StartInfo.Arguments = @"-i video.mp4 -i watermark.png -filter_complex ""overlay = x = (main_w - overlay_w) / 2:y = (main_h - overlay_h) / 2"" output%03d.mp4";


  


  This renders all my parts with the same "watermark.png" file as a watermark. But now i want to do something like this :

  


  converter.StartInfo.Arguments = @"-i video.mp4 -i watermark%03d.png -filter_complex ""overlay = x = (main_w - overlay_w) / 2:y = (main_h - overlay_h) / 2"" output%03d.mp4";


  


  "output000.mp4" has "watermark000.png" as a watermark,
"output001.mp4" has "watermark001.png" as a watermark,
"output002.mp4" has "watermark002.png" as a watermark, ...

  


  I need it in only one line, as if i would type it in cmd and it should work in c# with UseShellExecute=false.

  


  Any idea ?