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

[Gyan]

On Thu, May 18, 2017 at 5:53 PM, <trash at skrilnetz.net> wrote:

> 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
>
>
Since your command produces exactly (or upto) 4 frames at an interval of
720 seconds, you can add    -t 2900 -skip_frame nokey    before  -i
$input_path. Only keyframes are passed to the filters, so that should hurry
things up. Also, there's no need to keep the command running after 4 frames
have been found.