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• how to put a red frame before each video programmatically, when concatenating videos using ffmpeg

  7 février 2023, par Maifee Ul Asad

  To merge files with ffmpeg I'm creating a text file like this :

  


  file 'a.mkv'
file 'b.mkv'
file 'c.mkv'


  


  Then I'm running this command to concat these videos :

  


  ffmpeg -f concat -i file.txt -c copy merged.mkv


  


  But the thing is, I want to put red frame for three seconds in the middle of each video.

  


  Now I can get these videos' frame dimensions and create a video and modify the text file like this :

  


  file 'red.mkv'
file 'a.mkv'
file 'red.mkv'
file 'b.mkv'
file 'red.mkv'
file 'c.mkv'


  


  But this is not a programmatical approach, so is there any way I can concat videos and put red frames for three seconds (before every video) ?

  


  I want to generate that red frame video, on run time.

  


• Wave Goodbye ; What About VP8/WebM ?

  7 août 2010, par Multimedia Mike — Multimedia PressWatch

  Some big news in the geek community this past week came in the form of Google’s announcement that it would no longer be caring about its vaunted Wave technology. I was mildly heartbroken by this since I had honestly wanted to try Google Wave. Then I remembered why I never got a chance to try it : they made it an exclusive club at the beginning. I really did try to glean some utility out of the concept by reading documentation and watching videos and I had some ideas about how I might apply it. Then again, I try to think of a use for nearly any technology that crosses my path.

  It still struck me as odd : Why would Google claim that no one was interested in their platform when they wouldn’t give anyone a chance to try it out ? A little digging reveals that Google did open it for general use back around May 18. That date sounds familiar... oh yeah, VP8 was open sourced right around the same time. Maybe that’s why I don’t remember hearing anything about Wave at the time.

  But now I’m wondering about VP8 and WebM. How long do you think it might be before Google loses interest in these initiatives as well and reassigns their engineering resources ? Fortunately, if they did do that, the technology would live on thanks to the efforts of FFmpeg developers. A multimedia format has a far more clear-cut use case than Google Wave.

• Combine multiple video and single audio stream into a single output

  15 janvier 2020, par Prashant Saraswat

  I am trying to record an online meeting.
  During the meeting I will receive continuous audio and intermittent video

  • A. Audio B. Video1 C. Video 2

  The Audio stream will span the length of the call. The video1 and video2 streams will be somewhere in the middle.

  Assuming I know the timestamps for all of these streams, how do I combine them in one video ?

  Consider the scenario where the audio stream starts at Tbegin and ends at Tend. The video1 stream starts at T1 and ends at T2. The video2 stream starts at T3 and ends at T4.

  We can assume that the audio stream is of type mp3 and the other streams are of type mp4