[FFmpeg-user] exponential decay, is it possible?

Gyan Doshi gyandoshi at gmail.com
Tue Aug 7 12:06:09 EEST 2018

On 07-08-2018 01:24 PM, Michael Koch wrote:
> That's correct, at the beginning there is only one image temp0000.jpg

ffmpeg's image sequence demuxer, when not reading from a pipe, will 
probe for sequence size at initialization, so if an image doesn't exist 
at that stage, it won't be considered.

 > Is it possible that one of the inputs is the previous output frame?

There's no general recursive mechanism. You can always manually chain 
the same filter, however, this will get unwieldy quick.

For your particular case, you can use the geq filter

     ffmpeg -loop 1 -i starting-image.jpg -vf 
"geq=lum='p(X,Y)*pow(0.9,N)':cb='p(X,Y)'" -vframes 10 -q:v 2 out%d.jpg

The input luma is multiplied with 0.9 raised to the input frame count; 
count starts from zero. Chroma channels remain as-is.


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