QTGMC Vaporsynth settings

[Selur]

I know that video is TFF, but not sure if my HuffYUV video file’s header has set that value, this is why I try to set Input Order manually.

This way your are not changing the way Hybrid perceives the file you are changing the way QTGMC perceives the file.
Under:

• Base->Video->Scan Type
  
• Base->Show All Data
  
• Filtering->(De-)Interlace/Telecine->Deinterlace/Telecine Settings->Input scan type
  

Hybrid shows how the source is detected.
If you want to overwrite this value, i.e. since your source is badly flagged, your should use:
"Filtering->(De-)Interlace/Telecine->Deinterlace/Telecine Settings-Overwrite input scan type to" and set it to the value you want.

Looking in to Vapoursynth Script:

# 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=False) # new fps: 50

Does it mean that video will be interpreted not correctly, as BFF, since TTF=False?

This means that Hybrid assumed the source is TFF, but your configured QTGMC to assume the source is BFF.

Changing Input Order to “0” as it explained as BFF.

Looking in to Vapoursynth Script:
# 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) # new fps: 50

Looks like it is recognized as TFF instead of BFF?

Correct. This is a bug. -> Will fix.

Changing Input Order back to default “-1”.
Vapoursynth Script:
# 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) # new fps: 50

Looks like it reads file's header and sets TFF.

Correct, when using '-1' Hybrid sets the flag according to the detected input scan type.

Also how to change Sharpness value in QTGMC Deinterlacer, it is grayed out?

In QTGMC you need to set the preset to 'Custom' to change any of the options covered by presets.
If you set preset to 'Custom' you can select another preset that is the base of your values, but modify the values.
So if you want you settings to be based on 'Preset: Fast' you select:

• Preset: Custom (left upper corner)
  
• Preset: Fast (right side)
  
• enable Sharpness
  
• change the Sharpness value
  

Cu Selur

Ps.: send you a link to a dev version which should fix the TFF mixup.