nnedi3 chroma upscaler (VS)

import kagefunc as kgf
import vapoursynth as vs
core = vs.core

def to444(clip, w=None, h=None, join=True):

    uv = [nnedi3x2(c) for c in kgf.split(clip)[1:]]

    if w in (None, clip.width) and h in (None, clip.height):
        uv = [core.fmtc.resample(c, sy=0.5, flt=0) for c in uv]
    else:
        uv = [core.resize.Spline36(c, w, h, src_top=0.5) for c in uv]

    return core.std.ShufflePlanes([clip] + uv, [0]*3, vs.YUV) if join else uv

def nnedi3x2(clip):
    if hasattr(core, 'znedi3'):
        return clip.std.Transpose().znedi3.nnedi3(1, 1, 0, 0, 4, 2).std.Transpose().znedi3.nnedi3(0, 1, 0, 0, 4, 2)
    else:
        return clip.std.Transpose().nnedi3.nnedi3(1, 1, 0, 0, 3, 1).std.Transpose().nnedi3.nnedi3(0, 1, 0, 0, 3, 1)