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• ffmpeg sync parts of video or exclude intersection frames

  25 octobre 2014, par NadY

  I have two video files that make part of a bigger one, but both parts contain a portion that repeats itself.
  Eg. v1 : 00m-16m ; v2 : 10m-20m ; the part that repeats in both videos it’s 10m-16m

  Is there a way I could recreate the big video by automatically detect the intersection and exclude it from one of the videos ? Or can I find the time interval of the intersection ?

  Thanks !

• FFMPEG : Cut specific parts of a video, and merge them in a single file

  19 février 2017, par Jay D.

  I would like to cut out specific parts of a mp4 video, and merge back those parts to create a single video file. This is to make an animated preview of the video.

  More specifically :
  Cut out these parts of a video :

  • Part 1 : start time of the cut = 20% of total time ; end time of the
    cut = 20% of total time + 3seconds,
  • Part 2 : 40% of total time ; 40%nof total time + 3 seconds
  • Part 3 : 60% of total time ; 60% of total time + 3 seconds
  • Part 4 : 80% of total time ; 80% of total time + 3 seconds

  (The videos are more than 3 minutes long, so there should not be any overlap in the parts)

  Then merge those 4 parts in a new mp4 video file. How do you do that with FFMPEG ?

  Edit : so this is as far as I got for this question :

  I found answers to questions on "Superuser" and "Stackexchange" for these questions on FFMPEG :
   How to get video durations in seconds
   Cut part from video file with start/end positions
   Concatenate mp4 files

  So : Get total time of video :

  $ ffprobe -v error -show_entries format=duration \
  
    -of default=noprint_wrappers=1:nokey=1 -sexagesimal inputvideo.mp4

  With the -sexagesimal I should get the right time format to use after.

  Cut out part of video

  ffmpeg -ss [start] -i in.mp4 -t [duration] -c copy /path/videopart[number].mp4

  Right here I don’t know :
  How to do an operation on total time (20%, 40%... then 20% +3 seconds, 40% +3 seconds..)
  How to properly implement it in the code line

  Create a file videoparts.txt with the files names :

  $ cat videoparts.txt
  
  file '/path/videopart1.mp4'
  
  file '/path/videopart2.mp4'
  
  file '/path/videopart3.mp4'
  
  file '/path/videopart4.mp4'

  Then this should merge them in a single file :

  $ ffmpeg -f concat -i videoparts.txt -c copy outputvideo.mp4

• Resume transcoding a video with ffmpeg

  25 novembre 2014, par Jonathan.

  I have a node server that uses child-process to use ffmpeg to convert a video to mp4. However if the server crashes while transcoding, then I’d like to resume transcoding the file (similar to -C with curl).

  I figured I could just start transcoding the file from where it finished to a seperate file and then just concat the two. And while transcoding the file from where it finished works and the file that starts midway plays back fine, when I concat the two files with ffmpeg -i "concat:part1.mp4|part2.mp4" -c copy ouput.mp4 Only the first part will play, and when it gets to the second part it just stays on the last frame of the first part or goes black depending on the video player. (But playing part2.mp4 itself works fine)

  There isn’t any error during either conversion or the concat.