Notch filter / comb filter via shader

[Nesguy]

RetroTink-2X Pro (and 5X, etc) has a built in notch filter and comb filter, and an adaptive setting that switches between them.

Are there any existing shaders that do the same thing?

EDIT: We need something like this before the notch/comb filter shader is needed. Looks promising!

New CRT shader - Any interest?

I have been playing around with NTSC simulation. None of the existing NTSC shaders worked quite the way I wanted for crt-beans. I’ve created a new NTSC shader that: Converts to YIQ Low pass filters each component (at different bandwidths) and samples them Modulates the chroma onto the carrier frequency and then combines all three components Separates luma and chroma with a notch filter Demodulates the chroma components back to I and Q Low passes I and Q to remove the high frequency artifacts f…

[beans]

Adding a simple comb filter is straightforward. The tricky part is the adaptiveness—falling back to the notch filter when the comb filter would fail. I’ve been reading a couple of old patents, so that is on my radar. First I want to get the notch filter and luma trap working robustly, though, and I don’t have a lot of free time.

Some old consoles (like the Mega Drive/Genesis) won’t benefit from a comb filter because they don’t shift the chroma phase each line. In that case, a notch filter is about as good as you can get anyway. That’s assuming that we accurately simulate the phase behavior of each console, which might be the hardest part of this whole thing!

A couple of @DariusG’s shaders use a comb filter (although without adaptiveness, as far as I can tell). You can test those out.