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• ffmpeg - convert background to black ? [closed]

  22 juin 2022, par david furst

  the basic problem
  
convert all pixels in all frames of a source video to black if they have a white value below a certain threshold and output the results as a series of static images with no transparency.

  


  my solution so far
  
i am able to do this with a two-step process :

  


  

  1. convert pixels below the threshold to transparent using ffmpeg's colorkey filtre, outputting a series as PNG.

  


  2. use imagemagick to convert the PNG to JPEG.

  


  


  this approach is very slow. ideally i'd like to do everything in one go, within ffmpeg.

  


  the reason i haven't been able to do that so far is that the resulting transparency isn't discarded (as i'd hoped) when outputting to non-transparent formats like JPG, even if i try to 'discard' the alpha layer beforehand using combinations of split and lutrgb ; the resulting JPEGs still resemble the original images.

  


  my current filter chain :

  


  ffmpeg -hide_banner -y -i input.mp4 -f lavfi -i color=c=white \
    -filter_complex "[0:v]format=gray[src];
        [1][src]scale2ref[white][vid];
        [vid][white]blend=all_mode=multiply:shortest=1,colorkey=black:0.95" %05d.png


  


• ffmpeg to make black video with multiple audio and subtitles [closed]

  9 septembre 2024, par Tony M

  I want to use ffmpeg to make a video with only audio and subtitles in different languages. The video part can be a simple black background. I want to be able to switch between languages in video players like QuickTime.

  


  I've tried to get help from posts like this, but I couldn't figure out how to get it to work.

  


  To demonstrate that I've worked a long time on this, I'm showing what I've come up with below — but only steps (1) & (2) work. I can't get the subtitles step (3) to work.

  


  I've used ffmpeg for a long time, but never really understood it... I've only recently started to build my own commands, so the following probably looks awful to an expert :

  


  


  1. make a silent video using

     


     ffmpeg -loop 1 -i black.jpg -i silent.mp3 -acodec copy -shortest -vf scale=1000:136 silent.mov

     


  


  


  where m.jpg is a 500x68 black image and m.mp3 has 5 min of silence

  


  


  2. add 3 language (italian, french, german) using

     


     ffmpeg -i silent.mov -i ita.mp3 -i fre.mp3 -i ger.mp3 -map 0:v -map 1:a -map 2:a -map 3:a -metadata:s:a:0 language=ita -metadata:s:a:1 language=fre -metadata:s:a:2 language=ger ita-fre-ger.mov

     


  


  3. add subtitles using (doesn't work)

     


  


  


  ffmpeg -i ita-fre-ger.mov -i ita.srt -i fre.srt -i ger.srt -map 0 -map 1 -map 2 -map 3 -c copy -c:s mov_text -metadata:s:s:0 language=ita -metadata:s:s:1 language=fre -metadata:s:s:2 language=ger final.mov

  


• How to add a black bar on top and bottom of a video screen with a watermark on it ?

  3 mai 2017, par Neo Herakles

  I have this code to watermark my videos but I believe that the watermark may be distracting so I want to add black bars on top and on the bottom to place my watermark in, how could I do that ? Here’s my code for the watermarking of the video, I’m also appending an intro and outro to the presentation.

  for %%I in ("C:\Users\Administrator\Desktop\work\*.mp4") do ffmpeg.exe
  
  -y -i "%%I" -i white.png -i out1.ts -filter_complex "[1:v][0:v]scale2ref=iw/6:ih/18[logo][0v];[0v][logo]overlay=W-w-3:H-h-1,scale=hd720,setsar=1[vl];[2:v][2:a][vl][0:a][2:v][2:a]concat=n=3:v=1:a=1[v][a]"
  
  -map "[v]" -map "[a]" -r 20 -c:v libx264 -ar 48000 "C:\Users\Administrator\Desktop\Complete-videos\%%~nI.mp4"
  
  
  
  pause