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• avformat/aviobuf : Free white/black list in avio_context_free()

  12 août, par Andy Nguyen

  avformat/aviobuf : Free white/black list in avio_context_free()
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/aviobuf.c

• FFmpeg transparent PNG black outline issue

  5 février 2024, par kklmarvelmedia

  I'm encoding a video with a transparent PNG using ffmpeg. I noticed there's a slight black outline surrounding the image. Is there any way to remove it ?

  



  Output image :


  



  Transparent PNG sample :


  



  My ffmpeg command

  



  ffmpeg -hide_banner -y -ss 0.0 -t 8.5 -i C:\Users\Admin\Desktop\test_movies\6.mp4 -i C:\Users\Admin\Desktop\test_movies\text_and_emoji.png -filter_complex [0:v]setpts=PTS-STARTPTS,scale=640:640:force_original_aspect_ratio=decrease,pad=640:640:(ow-iw)/2:(oh-ih)/2:color=#18ffff[0v];[1:v]scale=556.24744:141.41884[1v];[0v][1v]overlay=(W-w)/2-(W/2-325.33328):(H-h)/2-(H/2-567.7075):enable='between(t,0.0,8.5)' -ac 2 -ar 44100 -vcodec libx264 -g 75 -r 20 -preset ultrafast -strict experimental C:\Users\Admin\Desktop\test_movies\test.mp4


  



  Last edit 1 :

  



  I tried using without [1:v]scale=556.24744:141.41884[1v], the output still have the slight outline

  



  Sample output :


  



  Sample code :

  



  ffmpeg -hide_banner -y -ss 0.0 -t 8.5 -i C:\Users\Admin\Desktop\test_movies\white.mp4 -i C:\Users\Admin\Desktop\test_movies\text_and_emoji.png -filter_complex [0:v]scale=640:640:force_original_aspect_ratio=decrease,pad=640:640:(ow-iw)/2:(oh-ih)/2:color=#18ffff[0v];[0v][1:v]overlay=(W-w)/2-(W/2-325.33328):(H-h)/2-(H/2-567.7075):enable='between(t,0.0,8.5)' -ac 2 -ar 44100 -vcodec libx264 -preset ultrafast -strict experimental C:\Users\Admin\Desktop\test_movies\test.mp4


  



  Last edit 2 :

  



  I tried another one with added alpha=premultiplied with latest ffmpeg version. It somehow removed the outline, but the quality of the picture reduced alot till it seems like it's pixelated. Plus. there's another unknown white layer at the back of the image.

  



  Output video


  



  Sample code :

  



  C:\Users\Admin\Downloads\ffmpeg-20180102-57d0c24-win64-static\bin\ffmpeg -y -ss 0.0 -t 8.5 -i C:\Users\Admin\Desktop\test_movies\white.mp4 -i C:\Users\Admin\Desktop\test_movies\text_and_emoji.png -filter_complex [0:v]scale=640:640:force_original_aspect_ratio=decrease,pad=640:640:(ow-iw)/2:(oh-ih)/2:color=#00ffff[0v];[1:v]scale=480:120[1v];[0v][1v]overlay=(W-w)/2-(W/2-325.33328):(H-h)/2-(H/2-567.7075):alpha=premultiplied:enable='between(t,0.0,8.5)' -ac 2 -ar 44100 -vcodec libx264 C:\Users\Admin\Desktop\test_movies\test.mp4


  



  Latest edit 3 :

  



  As suggested by @Mulvya, I combined his code with alpha=premultiplied and it seems alot better now, with very slight black outline (almost not visible)

  



  Output video :


  



  Sample code :

  



  C:\Users\Admin\Downloads\ffmpeg-20180102-57d0c24-win64-static\bin\ffmpeg -y -ss 0.0 -t 8.5 -i C:\Users\Admin\Desktop\test_movies\white.mp4 -i C:\Users\Admin\Desktop\test_movies\text_and_emoji.png -filter_complex [0:v]setpts=PTS-STARTPTS,scale=640:640:force_original_aspect_ratio=decrease,pad=640:640:(ow-iw)/2:(oh-ih)/2:color=#18ffff[0v];[1:v]premultiply=inplace=1,scale=480:120[1v];[0v][1v]overlay=(W-w)/2-(W/2-325.33328):(H-h)/2-(H/2-567.7075):alpha=premultiplied:enable='between(t,0.0,8.5)':format=rgb,format=yuv420p -ac 2 -ar 44100 -vcodec libx264 C:\Users\Admin\Desktop\test_movies\test.mp4


  


• Layer black & white video over background so black pixels are transparent in FFMPEG

  4 février 2018, par Dan Weaver

  I’m trying to blend a video containing black and white animated text over a static background image. I can successfully blend them but no matter what blend mode I use I can’t get the effect I want.

  I’m looking for an effect similar to Photoshop’s ’Add’ blend mode where the color values of each pixel are added together. This results in no change where the top layer (video) has black pixels, effectively making the black background appear transparent.

  This is what I’m trying to achieve :
  

  ffmpeg -i text.mp4 -loop 1 -i image.jpg \
-filter_complex 'blend=all_mode=addition' -t 1 result.mp4

  I tried all the modes of the blend filter but none of them produce this effect. I thought Addition would be the one to work but the resulting video has a pink tint. Maybe there is some mismatch between color channels ?

  How can I get the result I’m looking for ?