[FFmpeg-user] Documentation and feature request

[Michael Koch]

>> Feature request:
>> -- Decay filter, makes short flashes of light appear longer, with an
>> exponential decay curve. Like on an analog oscilloscope screen with long
>> persistence time. Could be used for videos of the night sky to make fast
>> meteors appear longer. Should work as follows:
>> For each pixel do:  Multiply the RGB values from the previous output
>> frame with a decay constant in the range [0..1], for example 0.95. Use
>> these RGB values for the next output frame. But if the RGB value from
>> the next input frame is brigher than this, then use the brighter value.
> Implemented as lagfun filter.
> See ffmpeg-devel mailing list.

Tested and working very good. Here is an example of a meteor in real 
time, left side without and right side with lagfun filter:
https://www.youtube.com/watch?v=Bc_lLGOHjjM

Michael