[FFmpeg-user] ffmpeg noise command: How is noise level defined

[Armin Kappeler]

Hi Lou,

Thank you for the reply.
Maybe I have to clarify. My code works fine, I don't have a question about
an error message. It is information, that I need for my conference paper.

I am referring to the following part of the documentation in section 9.53:
*Set noise strength for specific pixel component or all pixel components in
case all_strength. Default value is 0. Allowed range is [0, 100].*
*
*
I added noise of different strength to my video with the following commands
(4 examples):
ffmpeg -i vid1.avi -vf noise=alls=0:allf=t -vcodec libx264 vid2.avi
ffmpeg -i vid1.avi -vf noise=alls=25:allf=t -vcodec libx264 vid2.avi
ffmpeg -i vid1.avi -vf noise=alls=50:allf=t -vcodec libx264 vid2.avi
ffmpeg -i vid1.avi -vf noise=alls=100:allf=t -vcodec libx264 vid2.avi

Here I choose 4 different noise levels (0,25,50,100).
My question is now, how much noise is added to the video in each case?
One possibility is e.g. this:
For gaussian noise, the noise level corresponds to the variance of the
gaussian noise (-> variance 0 = no noise)