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• Concatenating chunks of videos with different formats using FFmpeg

  11 avril 2014, par SCC

  I was exploring the functionalities of FFmpeg recently. I have two different videos with different formats (e.g. mov and mp4). I will first split these videos up into smaller chunks, and concatenate them back with a mix of chunks from these two videos. However the concatenated video wasn't able to show properly. I did some research and found that mp4 cannot be concatenated using the normal concatenation method since it contains extra headers and information. Therefore I first converted all the videos into mpg, split them up, concatenate an convert back to mp4. However, still no luck on that.

  Below are the commands I used :

  // convert input (1st video) to mpg
  
  ffmpeg -i input.mp4 input.mpg
  
  
  
  // convert to keyframe video
  
  ffmpeg -i input.mpg -strict -2 -g 20 keyframe_input.mpg
  
  
  
  // split keyframe_input into smaller chunks
  
  ffmpeg -i keyframe_input.mpg -acodec copy -f segment -segment_time 0.3 -segment_list  s.m3u8 -vcodec copy -reset_timestamps 1 -map 0 split_input-%d.mpg
  
  
  
  // convert input2 (2nd video) to mpg
  
  ffmpeg -i input2.mov input2.mpg
  
  
  
  // convert to keyframe video
  
  ffmpeg -i input2.mpg -strict -2 -g 20 keyframe_input2.mpg
  
  
  
  // split keyframe_input2 into smaller chunks
  
  ffmpeg -i keyframe_input2.mpg -acodec copy -f segment -segment_time 0.3 -segment_list  s.m3u8 -vcodec copy -reset_timestamps 1 -map 0 split_input2-%d.mpg
  
  
  
  // concatenate video according to the video files written in mylist.txt
  
  ffmpeg -f concat -i mylist.txt -c copy output.mpg

  When I tried to concatenate these chunks of videos, errors were thrown out saying buffer underflow, packet size too large.

  Any FFmpeg experts out there to give some advices ?

• vmd : decode videos with no LZ buffer size provided - they might not need it

  1er juin 2013, par Kostya Shishkov

  vmd : decode videos with no LZ buffer size provided - they might not need it
  The buffer is used for an additional pass of frame compression, so videos
  
  can be coded without ever using it (and some are coded so indeed, e.g. in
  
  Woodruff and the Schnibble of Azimuth game).
  

  • [DH] libavcodec/vmdav.c

• How to batch auto-generate videos according to audio length

  16 septembre 2020, par yociba

  I have hundreds of folders of Spanish short stories, with each folder having dozens of individual .MP3 files for each dialogue spoken. Along with the .MP3 files, lies in the folder, a JSON file of the format ["folder1-dialogue-1", "folder1-dialogue-2",...].

  


  I want to generate images, each containing the text values of the JSON file, like folder1-dialogue-1 and generate videos combining that image with its corresponding audio (folder1-dialogue-1.mp3), and then merge all the videos in the folder into one - folder1.mp4

  


  How do I go about doing this ?

  


  P.S I'm not straight up asking for code, but just advice as to how I go about doing this.