mpeg2 mkv to x264 mp4 always heavy artifacts

[Selur]

Here's a script I would use as a base:

# Imports
import os
import sys
import ctypes
# Loading Support Files
Dllref = ctypes.windll.LoadLibrary("I:/Hybrid/64bit/vsfilters/Support/libfftw3-3.dll")
Dllref = ctypes.windll.LoadLibrary("I:/Hybrid/64bit/vsfilters/Support/libfftw3f-3.dll")
import vapoursynth as vs
core = vs.get_core()
# Import scripts folder
scriptPath = 'I:/Hybrid/64bit/vsscripts'
sys.path.append(os.path.abspath(scriptPath))
# Loading Plugins
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/SharpenFilter/CAS/CAS.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/DebandFilter/Flash3kDeband/flash3kyuu_deband.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/SharpenFilter/AWarpSharp2/libawarpsharp2.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/TCanny.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/libtemporalmedian.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/vcmod.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/DCTFilter.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/DeblockFilter/Deblock/Deblock.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/GrainFilter/AddGrain/AddGrain.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/DenoiseFilter/NEO_FFT3DFilter/neo-fft3d.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/DenoiseFilter/DFTTest/DFTTest.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/EEDI3.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/ResizeFilter/nnedi3/NNEDI3CL.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/libmvtools.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/temporalsoften.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/scenechange.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/fmtconv.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/SourceFilter/LSmashSource/vslsmashsource.dll")
# Import scripts
import mvsfunc
import muvsfunc
import G41Fun
import lostfunc
import havsfunc
# source: 'C:\Users\Selur\Desktop\1.mkv'
# current color space: YUV420P8, bit depth: 8, resolution: 720x576, fps: 25, color matrix: 470bg, yuv luminance scale: limited, scanorder: top field first
# Loading C:\Users\Selur\Desktop\1.mkv using LWLibavSource
clip = core.lsmas.LWLibavSource(source="C:/Users/Selur/Desktop/1.mkv", format="YUV420P8", cache=0, fpsnum=25, prefer_hw=0)
# making sure input color matrix is set as 470bg
clip = core.resize.Point(clip, matrix_in_s="470bg",range_s="limited")
# making sure frame rate is set to 25
clip = core.std.AssumeFPS(clip=clip, fpsnum=25, fpsden=1)
# Setting color range to TV (limited) range.
clip = core.std.SetFrameProp(clip=clip, prop="_ColorRange", intval=1)
# setting field order to what QTGMC should assume (top field first)
clip = core.std.SetFrameProp(clip=clip, prop="_FieldBased", intval=2)
# Deinterlacing using QTGMC
clip = havsfunc.QTGMC(Input=clip, Preset="Fast", TFF=True, opencl=True) # new fps: 50
# make sure content is preceived as frame based
clip = core.std.SetFieldBased(clip, 0)
# adjusting frame count and rate with sRestore
clip = havsfunc.srestore(source=clip, frate=23.976, omode=6, speed=9, thresh=16, mode=2)
clip = clip = lostfunc.DeSpot(o=clip)
# applying deblocking using DeBlock QED
clip = clip = havsfunc.Deblock_QED(clip)
# denoising using mClean
clip = clip = G41Fun.mClean(clip=clip)
# contrast sharpening using CAS
clip = core.cas.CAS(clip=clip, sharpness=0.800)
# adjusting output color from: YUV420P16 to YUV420P8 for x264Model (i420@8)
clip = core.resize.Bicubic(clip=clip, format=vs.YUV420P8, range_s="limited")
# set output frame rate to 23.976fps
clip = core.std.AssumeFPS(clip=clip, fpsnum=24000, fpsden=1001)
# Output
clip.set_output()

I attached the filter settings.
Not sure whether the original was PAL or NTSC, so I used sRestore to go for NTSC instead of PAL.
Also note that there are probably way better filtering settings, but this is what I would start with.

Cu Selur