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• How can I use ffmpeg to crop a part of a video by frames numbers including video and audio ?

  28 mars 2019, par Dubi Duboni

  I have a simple list :

  LReg.start = rise[i];
  
  LReg.end = fall[i];
  
  LR.Add(LReg);

  start and end are int’s in the end I have a List of the frames I want to extract from a video file. For example in index 0 of LR I have start 48 end 51
  In index 1 start 110 end 124

  So I want to loop over the List an save as a video file the part of a video file using ffmpeg according to the frame number start and end by jumping to this frames.
  Jump to frame 48 and create a video file out from frame 48 to 51 including 48 and 51. Then jump forward to the next group of frames 110 and 124 and so on.

  The problem is how to use ffmpeg to extract and save video files ?

• Webm video playing video & audio in Movies & TV app but will only play video in windows media player and html ?

  24 décembre 2019, par Kate LeVering

  I have created a webm video file with transparency with ffmpeg out of a series of png files. Then I add the audio track again in ffmpeg (I have tried both the opus and vorbis codecs). When I play it in the Movies & TV app it plays just fine (audio and video). In windows media player only the video plays. In html (inside a video tag) the video will play if it is set to ’muted’ but if it is not muted it doesn’t play.

  I am not sure what is going on. Does anyone have any insights. Do I need to run the audio from a seperate file ?

  Thanks, Kate

• Overlay video onto another video at multiple points in time

  22 décembre 2024, par kbcool

  I have a case where I want to have a background video and use a second video overlaying the first but at multiple points in time. The second video is shorter.

  



  So for example the main video is a minute long and the second video is 10 seconds. I want to overlay the second video once at 15seconds then again at 35 seconds and then again at 55 seconds (terminating when the main video does).

  



  I am able to get the second video to overlay successfully using overlay filter and between option but it only ever works for the first overlay. The second overlay seems to show the last or first frame of the video(??) but for the period I set in between. I am guessing it needs to be rewound and played somehow.

  



  Eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[out][1]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  I have also tried specifying the overlay as an input twice eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[out][2]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  The same thing happens.

  



  I'm sure the answer is simple and probably to do with how I'm using inputs but I'm not able to wrap my head around how to get the overlay video to play twice at different times on top of the original.

  



  I have also tried using the setpts filter to rewind the overlay but again the results are exactly the same.

  



  Eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[1]setpts=PTS-STARTPTS,[out]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  There are a lot of similar questions involving overlaying multiple videos but I can't find anything about reusing the same video at multiple points in time.