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Old 12th January 2021, 20:25   #21  |  Link
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What is QTGMC actually? NNEDI3 or EEDI3 or EEDI2 or something completely else?
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Old 12th January 2021, 20:56   #22  |  Link
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Originally Posted by richardpl View Post
What is QTGMC actually? NNEDI3 or EEDI3 or EEDI2 or something completely else?
QTGMC is a whole complex of filters (noise reduction, anti-aliasing and others).
The default is NNEDI3, but can choose another plugin.
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Old 13th January 2021, 18:22   #23  |  Link
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QTGM evolved from TempGaussMC, originally created by Didée. It is "a motion-compensated bob deinterlacer, based on temporal gaussian blurring".

It is a highly complex Avisynth script, using all sorts of plug-ins. Most notably but not limited to MVTools2 (motion compensation), MaskTools v2 (masking), NNEDI3 (interpolation) as well as RemoveGrain (denoising).

The core algorithm is this:
  • Bob the source clip. Temporally smooth the bob to remove shimmer then analyse its motion
  • More accurately interpolate the source clip (e.g. NNEDI3). Use the motion analysis from previous step to temporally smooth this interpolate with motion compensation. This removes shimmer whilst retaining detail. Resharpen the result to counteract any blurring
  • A final light temporal smooth to clean the result
Stages 0 & 1 use a binomial smooth (similar to a Gaussian) to remove deinterlacing shimmer. Stage 2 uses a simple linear smoothing.

NNEDI/2/3 and EEDI2/3 "only" are interpolators.

Simply put, they take an image with only half the lines (one field) and interpolate the missing lines. That alone would not make good deinterlacer, but it is an important "ingredient" for implementing stuff like QTGMC.

(Well, I think NEEDI3 alone would make a decent half-rate deinterlacer, but you do not want to use "pure" NEEDI3 for bobbing)
There was of course no way of knowing whether you were being watched at any given moment.
How often, or on what system, the Thought Police plugged in on any individual wire was guesswork.

Last edited by LoRd_MuldeR; 13th January 2021 at 18:45.
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Old 19th January 2021, 21:59   #24  |  Link
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BWDIF is "based on yadif with the use of w3fdif and cubic interpolation algorithms".
Could we replace w3fdif/cubic part for nnedi3 (or this filter described below) to have less jagged lines?
There is also very new deinterlacing filter in ffmpeg called estdif which is based on "Edge Slope+Tracing Deinterlacing Filter".
It seems to be some new approach and results are quite good, but can still produces jagged lines for static parts of image (this is where yadif is good). For actual combing removal it works very well- smooth diagonals and speed is not crazy bad.

Actually yadif could be bumped to yadifmod and then new interpolation filter. Could be best speed vs quality filter out there.

Last edited by kolak; 20th January 2021 at 01:11.
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