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• Cut videos and stack them with hstack in ffmpeg at the same time

  18 juillet 2018, par ekuusi

  I have two videos that I want to stack with hstack. The videos are not perfectly in sync so I would like to cut a bit from the beginning of one of the videos to get them to sync perfectly. Everything works fine using two concurrent commands :

  ffmpeg -ss 00:00:18 -i video1.mp4 -ss 00:00:02.000 -c:v libx264 left.mp4 

  followed by

  ffmpeg -i left.mp4 -i right.mp4 -filter_complex hstack output.mp4

  I’m wondering however if it is possible to do the trimming at the same time as stacking so that ffmpeg doesn’t have to encode the cut video twice. This would save a lot of time for me as I will be doing this cutting & merging multiple times.

  I tried various ways to achieve this in one single command, but to no avail so I have to turn to the community. Thank you for helping !

• ffmpeg crop videos and combine them

  9 août 2018, par Ben Perry

  I need to combine 2 videos vertically or horizontally. But before this i need to crop one or two of the videos.

  Both video sizes need to be 720x640. I need to combine 2 video that has 720x1280 resolution. I first crop them to 720x640 (crop 320px from top and 320px from bottom), then combine vertically.

  I can combine same size videos with the command :

  ffmpeg -i 1.mp4 -i 2.mp4 -filter_complex
  "[0:v]scale=520 :-1[v0] ;[1:v]scale=520 :-1[v1] ;[v0][v1]vstack" -c:v
  libx264 -crf 23 -preset veryfast output.mp4

  This command is working but i need a crop operation for this command.

  Any idea ?

  Thanks

• Concatenate multiple videos with a black screen interval into one video

  21 mars 2016, par AHC

  I am using ffmpeg to join a bunch of videos together.
  I am using the classic join ffmpeg code :
  

  ffmpeg -f concat -i joinlist.txt -c copy joinedfile.mp4

  but the problem is that the videos are of different formats, encodings, but the same size : all 640x480. I want to join them all and put a black screen video with no sound every other video :

  video1 + black_screen_video + video2 + black_screen_video + video3 ...

  I generated a black screen video of 2 seconds duration using :

  ffmpeg -f lavfi -i color=c=black:s=640x480:d=2 black_screen_video.mp4

  so all of the videos are of the same size : 640x480, and 25 fps but different codecs. The videos have sound, except for the black screen video.
  I can’t do anything manual, because the number of videos are around several hundred. So it has got to be an automatic way to do all this.

  When I joined them together using the above code, the resulting video does not play correctly at all.

  I know that I have to re-encode them, but how to do this to all these videos at once, with one line of code ?

  Update :
  I am already using with success this code to join them together, but only three, if I have more than one hundred, it is time consuming to write down one by one :

  ffmpeg -i vid1.avi -i vid2.avi -i vid3.avi -filter_complex "[0:v:0] [0:a:0] [1:v:0] [1:a:0] [2:v:0] [2:a:0] concat=n=3:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" output.mp4

  but this is joining only the videos, not looping the black screen video. When I do with black screen, ffmpeg gives me stream matching errors.