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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

  


  

  


• avcodec/opus : always use ambisonic layout for mapping family 2

  18 mars 2022, par James Almer

  avcodec/opus : always use ambisonic layout for mapping family 2
  No need to use a Custom layout when the non diegetic channels can be
  
  described as a standard mask.
  This fixes :
  45684/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LIBOPUS_fuzzer-5039410989629440
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/opus.c

• swresample/rematrix : handle 22.2 as a 9 channel layout

  6 août 2020, par Jan Ekström

  swresample/rematrix : handle 22.2 as a 9 channel layout
  This is as far as 22.2 follows the same channel order as
  
  WaveFormatExtensible's channel mask (and the AV_CH_* defines).
  After LFE2 the side channels would follow, but that offset of
  
  one stops us from utilizing them without further tweaks.
  This change was verified by using swresample to downmix to 5.1,
  
  and then feeding that to WASAPI.
  

  • [DH] libswresample/rematrix.c