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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 ?

  


• FFMpeg video stopmotion

  22 juillet 2020, par Praveen Tamil

  I would like to create stop motion video from original video.
The logic is take frame at specified interval. 
And play the video with specified playback rate.

  



  For example,
  
The original video duration is 114.048 seconds.
  
The output video playback rate 5 times faster than source video.
  
Take each frame at the interval of 1 seconds. so the final video duration should be (22.81 = 114.048/1*0.2) seconds

  



  Below is the screenshot of demo

  



  For this I need ffmpeg code

  



  ffmpeg -r 1 -i D:\21-03-2018\15305154945b39d026a18da.mp4 D:\21-03-2018\output.mp4

  


• Why does my H.264 video have a green overlay after video filter is applied ?

  11 juin 2019, par d1che

  When executing the following code :

  



  ffmpeg -i input.mov -c:v libx264 -preset veryslow -pix_fmt yuv420p -filter_complex "drawtext=fontfile=font.ttf:fontcolor=white@1:fontsize=h/6:x=(w-text_w)/2:y=(h-text_h)/2:text='Henk de Vries'[watermark];[0][watermark]blend=all_mode=difference:all_opacity=1" output.mp4

  



  The output file has a green overlay. When using other blend modes, results vary with some modes displaying correct colors and others green and pink.

  



  I know that the input file has yuv420p colorspacing. I think the blend filter only supports rgba modes but I am not sure.

  



  How can I avoid the green overlay and get the original colors ? (e.i. what the original input video looks like)