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• why is streaming to an flv server with ffmpeg only showing black/blank video for clients ?

  6 septembre 2012, par rogerdpack

  When I stream to an flv server, like flash media server, using ffmpeg, like

   ffmpeg -i input -vcodec libx264 rtmp://hostname/streamname

  it turns out black. Why is that ?

• Add 2 seconds of blank/black video with ffmpeg

  22 avril 2016, par user3076099

  Let’s say I have two videos I want play simultaneously. movieA.mp4 is 38.6 seconds duration, and movieB.mp4 is 31.14 seconds duration. Using ffmpeg is there an easy way to fill the end of movieB.mp4 with black silence so that it is exactly 38.6 seconds (matching movieA.mp4). There’s a very niche technical reason I want to do this, so don’t ask haha !!

  Also if possible, but less important, a way to remove this afterwards.

  Been searching for 2 days for any sort of easy way around this without luck !!!

  Thanks so much in advance !

• Concatenate multiple videos with a black screen loop 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.

  update :

  here is the console image :
  

  2nd update :

  a very long list of errors in red, of which a screenshot here :