[FFmpeg-user] Thumbnail tile slow on big video files

[trash at skrilnetz.net]

Hi,

I run the code below to produce a tile thumnail from video files. That  
seems to be very slow on big video files. Anything that I do wrong, or  
I could improve to speed up processing?

ffmpeg -ss 720 -i $input_path -f image2 -vframes 1 -aspect 4:3  
-filter:vf  
select='isnan(prev_selected_t)+gte(t-prev_selected_t\,720)',scale="'if(gt(a,4/3),128,-1)\':'if(gt(a,4/3),-1,96)\'",pad="w=128:h=97:x=(ow-iw)/2:y=(oh-ih)/2:color=black",tile=4x1 -y  
$output_filename

Thanks!
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