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• How to (visually) losslessly compress a video with GPU acceleration in ffmpeg ?

  4 juin 2022, par Tizian Heckmann

  I am trying to compress a video in ffmpeg with GPU acceleration, but the result always looks bad. This is what I have tried and none of this has worked for me :

  


  Preset 18 is called "best quality" when looking at ffmpeg -h encoder=hevc_nvenc
  
ffmpeg -i input.mp4 -c:v hevc_nvenc -preset 18 compressed.mp4

  


  Also :
  
ffmpeg -i input.mp4 -c:v h264_nvenc -preset 18 compressed.mp4

  


  Unfortunately, the preset lossless is deprecated. When trying
  
ffmpeg -i input.mp4 -c:v h264_nvenc -preset lossless compressed.mp4
  
the output file just grows enormous.

  


  Any help is appreciated.
  
Edit : Since my question is being received as inappropriate by the community, I would like to know why. This was my first question, any advice on how to word it better or tell me why it just does not fit here would be appreciated. Thank you.

  


• Merge commit ’0670acc4f1c4ceb16968818a654e07a3f550a8c9’

  12 mai 2015, par Michael Niedermayer

  Merge commit ’0670acc4f1c4ceb16968818a654e07a3f550a8c9’
  * commit ’0670acc4f1c4ceb16968818a654e07a3f550a8c9’ :
  
    dca_parser : Extend DTS core sync word and fix existing check
  Conflicts :
  
  	libavcodec/dca_parser.c
  See : e80b2b9c81716a5d9f559c04cfe69d76b04e4cd3
  
  Merged-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/dca_parser.c

• How to preserve transparency when using png to make video with ffmpeg

  27 septembre 2016, par Ryan James

  I have a series of png’s that have an alpha channel as a background. Each file is named like file_name.0001.png and so on, in subsequent order. I’d like to join these png’s into a video with ffmpeg and maintain the transparency.

  I’ve tried a couple of things but I suspect I’m running into a codec issue. When I run ffmpeg, the video is created but the background is black.

  If it makes a difference, I’m wanting to use the video in Microsoft Powerpoint. Thanks !

  Edit
  The suggested duplicate is very close to what I was looking for, thank you ! The only reason it’s not a complete solution is none of the options presented in the other thread work well with Microsoft Powerpoint. None of the codecs used in the suggested solution play well with Powerpoint. This is not the fault of ffmpeg, but of Powerpoint.

  Though ffmpeg doesn’t seem to be able to do what I need, I found that imagemagick did the trick. I was able to create a gif from the images and the alpha channel was preserved. I used the following :

  convert -dispose 3 -coalesce images.*.png gif_file_name.gif

  The -dispose 3 is critical as it tells imagemagick to clear the image prior to overlay, otherwise, you can see each image overlaid on each other (since they have the transparent background).