[HELP] Video stuttering after processing

[Selur]

Your clip is not interlaced. It's encoded as progressive H.264. (someone messed up there during the digitalization)
Fieldmatching your clip shows that there are a few duplicate frames:
6&7
30&31
53&54
100&101
...
which do not follow a pattern. Also, there are still some combing artifacts left after the field matching.
=> this is not a bug in QTGMC, this is you feeding it non-interlaced content and expecting it to do something it is not designed to do.

To deal with the combing artifacts, what I would suggest is:

• use "Filtering->Vapoursynth->Frame->Misc->TFM" for the field machting.
  
• use "Filtering->Vapoursynth->Denoise->QTGMC" with "Input type" set to "3" for the removal of the residual combing.
  
• use "Filtering->Vapoursynth->Frame->Misc->FillDuplicates" to replace the duplicate with interpolated frames.
  A threshold of '0.005' seems to work for me correctly to identify the duplicates.
  You should move the "QTGMCFilter" filter before the "FillDuplicates" filter. ("Filtering->Vapoursynth->Misc->Filter Order/Queue")
  

Additionally, I would suggest:

• Cropping the source (left=6, right=8, top=0, bottom=6)
  
• maybe use "Filtering->Vapoursynth->Sharpen->aWarpSharp2" with 'Depth' set to '16' or similar, too shrink the black lines a bit.
  
• look into some color adjustments (maybe "Filtering->Vapoursynth->Color->AutoWhite" or some manual adjustments)
  

Here's an encode of the sample.
Didn't do any denoising, deblocking or similar, main idea was to show how to deal with the combing artifacts.


Cu Selur