Trying to Create a Flickering Expression with Frequency Control for Slider

EDIT: I have since found a method that is very close to my desired result with an senoise node. I’ll be adding it to a video tutorial in the future.

Hello everyone.

I am attempting to create a video of a flickering light. I have two nodes, one of the footage, and a grey solid node set to white. Both are going into a merge node set on Color Dodge.

From here I can either adjust the solid node’s color slider or the merge node’s mix slider to change the intensity of the light source.

In the past I’ve used the Wiggle expression in After Effects for something similar but I can’t get a same result in Natron.

The issue is I need the slider value to be random but using a random expression has the slider jump around violently since it changes the value every single frame. This make the frequency of the flickering way too intense. I need to lower the frequency so the flickering is smoother.

I’ve tried using random(0,1,frame) with different division values like /3 and /10 and that does let me change how often the slider jumps around, however the transition between the jumps isn’t smooth at all, it looks like steps.

Like this:


But this is what I need it to look like.


The similar posts I found use the Shaker and Wiggle plugins but those only work on position and rotation. I did find THIS post with is basically the result I’m after but that uses a SeExpr node and I couldn’t make head or tails from the documentation. I’d like to have an expression I could apply to any slider.

Any help would be greatly appreciated.