If you're talking about smoothing, if you can send 4k120 10/12 bit to your C2 (if memory serves the C2 has HDMI 2.1), what I'd do is set

120fps (of course... why else would I mention 4k120?)
Frames interpolation mode: 1m
SVP Shader: Complicated
Motion Vectors Precision: Half
Motion Vectors Grid: 6px. small 2
Decrease grid step: By two with global refinement
Search radius: small
Wide search: strongest
Width of top coarse level: I choose large, but I don't think I've noticed much of a change
Same with search radius... I don't know that I can tell it's doing anything. I suspect small search radius is best because there's a "small (fast)", but now I think I could be wrong about that, because Complicated > Average > Simple > Simple Lite > ... > ... > fastest (slow PCs)

I have some questions but don't want to commandeer or derail OP's thread, so I'm going to make another one

Both SSimDownscaler and KrigBilateral I get from here and are frequently updated.

https://gist.github.com/igv

Yep. That's where I got the last copy from too. It's configured for Catmull Rom. The ones I saw configured for Mitchell must have been local variations by other users.

https://gist.github.com/igv

ontop

glsl-shader="C:\Users\Username\AppData\Roaming\mpv\Shaders\SSimDownscaler.glsl"

FYI While I think SsimDownscaler by default was configured for Mitchell, some configs out there have it configured for Catmull Rom.

The order of the shaders if you want to use them is also important, last year with the original post at the top, the order was completely wrong.

But as @dawkinscm said you don't need to use shaders, also can remove the configs they suggested removing. I will do more testing in the coming weeks probably and try to remember to update in the future as well.

Not sure which TV you are using, or which monitor, but for target-peak=800 in the code below, I have 800 because that's the maximum NITS of brightness for the LG C2 42", C3 would be the same, G3 would be different because it uses MLA technology and can go higher. QD-OLED can go higher as well, depending on the product.

ontop
fullscreen=yes
d3d11-exclusive-fs=yes

volume=100
volume-max=100
video-sync=audio
hr-seek-framedrop=no

fbo-format=rgba16hf

vo=gpu-next
gpu-api=d3d11
hwdec=d3d11va
gpu-context=d3d11
drm-vrr-enabled=no
d3d11-sync-interval=1

target-peak=800
target-trc=pq
target-prim=bt.2020

tone-mapping=spline
tone-mapping-mode=luma
gamut-mapping-mode=perceptual
tone-mapping-param=bt.2390
tone-mapping-max-boost=2.0

dither=error-diffusion
error-diffusion=burkes
dither-depth=10
spirv-compiler=auto

target-contrast=inf
target-colorspace-hint=yes
hdr-compute-peak=yes

scale=ewa_lanczos
cscale=ewa_lanczos
dscale=ewa_lanczos
tscale=ewa_lanczos

osd-level=1
osd-bar-w=25
osd-color=0.5
osd-bar-align-x=0
osd-bar-align-y=-1

glsl-shader="C:\Users\Username\AppData\Roaming\mpv\Shaders\FSRCNNX_x2_8-0-4-1.glsl"

glsl-shader="C:\Users\Username\AppData\Roaming\mpv\Shaders\KrigBilateral.glsl"

glsl-shader="C:\Users\Username\AppData\Roaming\mpv\Shaders\SSimDownscaler.glsl"

Old post, my config has updated since then.

Agree with lots of what @dawkinscm said above too

@bombadilio DV has worked for a while I believe, but not with RIFE.

If you use RIFE, dolby vision will not work properly and you'll get issues. I'll try to remember to post my new configuration later, remind me tomorrow in case I forget @bombadilio

Yes, please post your new config when you get the chance. Thanks!

Agree with lots of what @dawkinscm said above too

@bombadilio DV has worked for a while I believe, but not with RIFE.

If you use RIFE, dolby vision will not work properly and you'll get issues. I'll try to remember to post my new configuration later, remind me tomorrow in case I forget @bombadilio

ontop
vo=gpu-next
fbo-format=rgba16hf

spirv-compiler=auto

dither-depth=auto

scale=ewa_lanczossharp
cscale=ewa_lanczossharp
dscale=ewa_lanczossharp
sigmoid-upscaling=yes

glsl-shader="C:\Users\YourUsernameHere\AppData\Roaming\mpv\Shaders\KrigBilateral.glsl"
glsl-shader="C:\Users\YourUsernameHere\AppData\Roaming\mpv\Shaders\FSRCNNX_x2_16-0-4-1.glsl"
glsl-shader="C:\Users\YourUsernameHere\AppData\Roaming\mpv\Shaders\SSimDownscaler.glsl"

I'm not going to comment on config for OLED. It's best you experiment for yourself. Here are some points to think about.
dither-depth=auto and spirv-compiler=auto is the default so not necessary
fbo-format is disabled in gpu-next so is not needed and won't work anyway.

KrigBilateral isn't really necessary and although I've never seen it myself it can apparently cause mistakes.
Is FSRCNNX_x2_16-0-4-1.glsl that much better than FSRCNNX_x2_8-0-4-1.glsl considering the extra processing power needed?
Do you need to use both FSRCNNX_x2_16-0-4-1.glsl and SSimDownscaler.glsl? That's a lot of processing and sharpening.
SSimDownscaler.glsl is configured by default for Mitchell but you are using ewa_lanczossharp. So that is not optimal.

You are sharpening in upscale, shader and downscale. Although FSRCNNX might not be doing anything because by default it only works when a x2 or greater upscale is needed. This might be why you can get away with running FSRCNNX_x2_16 and SSimDownscaler which are very GPU heavy.
Some shaders overwrite others so it's best to use append when you want multiple shaders to work at the same time.

Hope this helps a little.

Any luck with the latest update getting DV files to play? I am getting red tonemapping like an afterglow for about 1/4 - 1 second on each fast forward. Would love to know what your prime settings are. Only difference is I have a 4090.

Old Information here removed - Check my comments below for updated configs: