[HELP] Video stuttering after processing

[Bartoloni]

Strange: I see the 'stuttering' already in the source during playback.

not so hard like on final output, for what i can see... the original is shaky... but the final is worse

[Selur]

Then I do not see how this could be caused by Hybrid.
Check the preview, to me it looks like the source,..
You can also try a different deinterlacer,..

[Bartoloni]

With avysynth. is the same. ( small update )

[Selur]

Like I wrote, try a different deinterlacer.
For example, Yaifmod (mode: 0).

Cu Selur

[Takaji]

I've also been having this problem with QTGMC - but only when I enable Bob. (I'm also using bottom field first.) If I don't enable it, the outputted video movement scenes are smooth. I haven't enabled any other filter settings.

I tried using Yadifmod, mode 0, and there's also no stuttering.

So, I originally started using Hybrid since I heard that QTGMC handles deinterlacing best, but it seems there's perhaps an issue with it.

Can anyone else confirm? Here's a link to the video clip I'm testing with: https://mega.nz/file/mNkAHJ7R#TxoBE8DciH...S_d5YtvPl8

[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

[Takaji]

Your clip is not interlaced. It's encoded as progressive H.264. (someone messed up there during the digitalization)

First of all, thank you for the in-depth reply, especially with where to change settings. I'm a new user and it helps a lot!

That would be me messing up during the digitalisation... I'm attempting to capture some video from a 8mm digital video source, and I've followed another guide which uses OBS for capture. I've read a few forum posts elsewhere now which state that OBS can only record progressive video, despite the fact that I've disabled deinterlacing in the capture device's driver:



I will search for another way to use my capture device to record interlaced video and then revisit this thread to see if I still encounter the same issues.

@Selur assuming I can capture interlaced video, should the problems with duplicate frames and combing go away? Additionally, and slightly out of scope of this thread, is there a certain video format I should be capturing my video in for best results, assuming that I'll be doing additional filtering in Hybrid afterwards?

Thanks for sharing your example encode, it looks a lot better than mine!

[Selur]

Note: I have never used OBS. (not sure whether it is even recommended for this, better ask over at https://www.digitalfaq.com/forum/video-capture/ or https://forum.videohelp.com/forums/10-Capturing-and-VCR)

For the capturing, since your input is interlaced, you should compare:
a. Deinterlace (bob, preferred) in the drivers and encode progressively
b. Not deinterlace (weave, would be correct here) in the drivers, but deinterlace in OBS and encode progressively
c. Not deinterlace (weave, would be correct here) in the drivers, bot deinterlace in OBS and encode interlaced, then later deinterlace in Hybrid (or another tool). <= probably the best choice. (No clue how to tell OBS to save interlaced)

General note: you should capture to a lossless format. (No clue how to tell OBS to capture to a lossless format)

assuming I can capture interlaced video, should the problems with duplicate frames and combing go away?

Drop-outs / Duplicate frames might still occur, but QTGMC should be able to properly remove all the combing.

is there a certain video format I should be capturing my video in for best results, assuming that I'll be doing additional filtering in Hybrid afterwards?

Any lossless format that OBS supports should be fine.

Cu Selur

[Takaji]

Tried a new capture method using VirtualDub2, and used UtVideo YUV422 BT.601 VCM codec to get a lossless capture.

Sample here: https://mega.nz/file/uN0hHZYa#FOMeWPeXQO...dYNIQgkJgk

I then tried using QTGMC deinterlace with top field first (this despite Hybrid telling me it was bottom field first on analysis), and the result is a nice and smooth video.

[Selur]

Happy that worked out.

Cu Selur