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• ffmpeg vaapi - scale a video keeping the aspect ratio and padding with black lines

  26 décembre 2022, par Rusty Lemur

  I'm trying to use my Vega 11 GPU to perform hardware accelerated transcoding of some video files to a resolution of 1280x720. I would like to keep the original aspect ratio and add black bars to the borders as necessary. I can get the scaling to work with the following :

  


  ffmpeg -hwaccel vaapi -hwaccel_output_format vaapi -vaapi_device /dev/dri/renderD128 -i input.mp4 -codec:v h264_vaapi -vf scale_vaapi=w=1280:h=720,setsar=1:1 output.mp4


  


  But some of the image gets stretched with that, and the original aspect ratio is not preserved.

  


  On the Raspberry Pi I can get the effect I want with the following :

  


  ffmpeg -i input.mp4 -b:v 2M -vf scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:'(ow-iw)/2':'(oh-ih)/2',setsar=1 -vcodec h264_v4l2m2m -num_capture_buffers 128 output.mp4


  


  But when I try to use the force_original_aspect_ratio and pad options with the vaapi codec, I get the following error :

  


  ffmpeg -hwaccel vaapi -hwaccel_output_format vaapi -vaapi_device /dev/dri/renderD128 -i input.mp4 -codec:v h264_vaapi -vf scale_vaapi=w=1280:h=720,pad=1280:720:'(ow-iw)/2':'(oh-ih)/2',setsar=1:1 output.mp4

Impossible to convert between the formats supported by the filter 'Parsed_scale_vaapi_0' and the filter 'auto_scaler_0'
Error reinitializing filters!
Failed to inject frame into filter network: Function not implemented
Error while processing the decoded data for stream #0:0


  


  Is there another option I should use to get the padding and keep the original aspect ratio ?

  


• lavfi/fade : fix black level for non studio-level pixel formats

  29 mars 2012, par Stefano Sabatini

  lavfi/fade : fix black level for non studio-level pixel formats

• 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