[FFmpeg-user] lenscorrection and vignette filters

[Michael Koch]

Hi all,

I found a bug in the documentation of the lenscorrection filter:
https://www.ffmpeg.org/ffmpeg-all.html#lenscorrection

It's written there "0.5 means no correction" for the coefficients k1 and 
k2.
This can't be right, or the formula is wrong. It's obvious that the 
formula makes no correction if k1=k2=0.

For positive k1 and k2, r_tgt is always smaller than r_src. That means 
in the target image there are undefined pixels at the edges. Which color 
is used to fill these pixels? There should be a "fillcolor" parameter as 
in the rotate filter.

Other question:
Which formula is used for the vignette filter?

Thanks,
Michael