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• FFmpeg : Removing black outline on overlay after alphamerge

  9 novembre 2023, par trmd

  Similar question : FFmpeg transparent PNG black outline issue

  


  When using FFmpeg to create a GIF from an mp4, masking the video using alphamerge and a PNG-mask, and overlaying a circle outline, black lines occur on both the video and the circle in the final GIF.

  


  From this question, some suggestions are made to add alpha=premultiplied and format=rgb,format=yuv420p in the overlay-filter. This removes the black line (on the circle), but the masking from alphamerge no longer works.

  


  Filter used which generates black outlines :

  


  [0][1]alphamerge[merged];
[merged][2:v]overlay=
    format=auto:
    alpha=premultiplied[withCircleOverlay];
[withCircleOverlay]scale=${size}x${size}[scaled];
[scaled]split[s0][s1];
[s0]palettegen=reserve_transparent=on:transparency_color=ffffff[p];
[s1][p]paletteuse


  


  Filter used which removes outlines, but also cropping :

  


  [0][1]alphamerge[merged];
[merged][2:v]overlay=
    alpha=premultiplied:
    format=rgb,format=yuv420p[withCircleOverlay];
[withCircleOverlay]scale=${size}x${size}[scaled];
[scaled]split[s0][s1];
[s0]palettegen=reserve_transparent=on:transparency_color=ffffff[p];
[s1][p]paletteuse


  


  Command used :

  


  ffmpeg -i movie.mp4 -i mask.png -i circle.png -filter_complex <filter> output.gif&#xA;</filter>

  


  What I've tried :

  


  

  • Changing the format-parameter on overlay to a lot of different values.

  


  • Changing the order of the filters.

  


  • Playing around with running multiple ffmpeg-passes : First doing the merging, saving this to a file, and then adding the circle afterwards. I think this in principle should work if I tinker with it enough.

  


  


  Are there any ways to get around this issue ?

  


  Image with black outlines

  


  

  


  Image without outline, but also without alphamerge cropping

  


  

  


• How to round a square image and put it on video

  27 juillet 2022, par Erez git

  I've a video, videoPath.
I've a square image, squarePath.

  


  This code places the squarePath on the video at a desired position to output, outputVideo.

  


  final String[] cmd = new String[]{"-i", videoPath, "-i", squarePath, "-filter_complex", "[1:v][0:v]scale2ref=(300/300)*175:175[wm][base];[base][wm]overlay=(main_w-overlay_w)/2:(343)", "-pix_fmt", "yuv420p", "-c:a", "copy", "-y", outputVideo};

int res = FFmpeg.execute(cmd);


  


  I would like to round the squarePath in the same command. Is it possible ?

  


  This is the code to make it rounded as I found :

  


  ffmpeg -i avatar.png -i mask.png -filter_complex [0]scale=400:400[ava];[1]alphaextract[alfa];[ava][alfa]alphamerge output.png


  


  but I don't understand how to merge these two commands.

  


• flacdec : do not overwrite a channel layout set by the caller

  25 mai 2014, par Anton Khirnov

  flacdec : do not overwrite a channel layout set by the caller
  The channel layout mask for non-standard layouts is typically stored at
  
  the container level (as a vorbiscomment tag) for FLAC.
  

  • [DH] libavcodec/flac.c