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• -ss in ffmpeg causes black frames

  26 avril 2016, par Demonedge

  I use ffmpeg to cut a video into clips. By this command :

  ffmpeg -ss 00:00:00 -i video.mp4 -to 00:01:00 -c copy cut.mp4

  Ffmpeg has to cut at key frames, thus when I concatenate each clip back to the entire video, there are some repeated frames at the beginning of each clip. Then I found this command :

  ffmpeg -i video.mp4 -ss 00:00:00 -to 00:01:00 -c copy cut.mp4

  By putting -i first solves the above problem, but it introduces some frozen frames when I concatenate my video clips back into the whole video. In fact, I saw it introduces some black frames at the beginning of each clip, so when I concatenate these clips back, there are frozen frames.

  So is there any way that I can cut my video into clips accurately without introducing black frames or frozen frames in ffmpeg ?

• PHP - How to get Shell errors echoed out to screen

  26 février 2013, par Ash

  I am in the process of using shell_exec() for the first time. I am trying to convert some video files on my server using the ffmpeg shell script.

  When I the below code in the browser, it returns NULL :

  var_dump(shell_exec("ffmpeg -i /var/www/html/sitedomain/httpdocs/tmp/ebev1177.mp4"));

  However when I run the equivalent code in my terminal :

  > ffmpeg -i /var/www/html/sitedomain/httpdocs/tmp/ebev1177.mp4

  I get back a whole load of useful information which ends in an error "At least one output file must be specified"

  Why is this info not being passed back to my PHP script so I can echo it out ?

• Use ffmpeg to pan right over an image and then pan left to the original location

  4 février 2024, par user1517922

  I'm using this command to pan to the right for 5 seconds on an image (like a 1080x1080 window moving across a larger image, 500px from the top) :

  


  ffmpeg -loop 1 -r 30 -i image.jpg -vf crop=w=1080:h=1080:x=n:y=500 -frames:v 150 -pix_fmt yuv420p -preset fast -crf 30 video.mp4

  


  I'd like to pan back to the left for 5 seconds to end up at the same spot.

  


  The desired affect is when the video is on loop the square window pans right for 5 seconds then back left for 5 seconds then repeats, smooth and without flicker.

  


  I suspect I need to use zoompan, but I haven't had success trying that.