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• How to take perfect screenshots of UHD/HEVC vídeos ?

  5 août 2018, par kdantas

  Could someone give a tip to improve the quality of screenshots taken from .m2ts UHD HEVC files of seedbox running rtorrent/rutorrent, installed on Ubuntu Server Armhf 16.04 "Xenial Xerus" (32bits) OS ? Many screenshots are shown without any image definition. I don´t have problem with the screenshots of FHD videos or .mkv UHD videos. The Screenshot plugin use the ffmpeg software. I don´t know if is necessary any adjust in the lines codes of the plugins, or if exist a best way to take screenshots of UHD videos through the terminal SSH ?

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• 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.

• 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