BlockOverlap

Deblocking Filter

Plugin for Avisynth 2.5
Version 0.2 - 26 October, 2005
Copyright (C)2005 Alexander G. Balakhnin aka Fizick.
http://bag.hotmail.ru

Introduction

Great motion compensation plugin MVTools by Manao often produces local  blocking artifactes on compensated clip.

BlockOverlap plugin deblock it by using two input compensated clips with shifted block positions.

This plugin make blocks windowed overlapping (uniform or kernel non-uniform blending).

It uses high weight of central (kernel) parts of blocks of two frames, and lower weight of edges parts of blocks to form more smooth output frame.

The blending also greatly decreases the noise on compensated frame.

The deblocked and denoised output can improve the temporal motion compensated filtering of original clip.

Of course, the processing speed is halved due to two motion estimation and compensation.

This plugin may be also useful for other filters with block artifactes (Dust, FFT3Dfilter ?).

Function parameters

BlockOverlap(clip, clip "shifted", int "xblocksize", int "yblocksize", float "kernel")

first parameter - first input clip
shifted - second clip, its blocks must be shifted by half of block diagonal (no default)
xblocksize - horizontal block size (integer, default=8)
yblocksize - vertical block size (integer, default=8).
kernel - blending window form (float, from 0.0 (uniform) to 1.0 (cosine kernel), default =0.5).

Features and limitations

  1. Works only in YV12 and YUY2 color format.
  2. Directly works with progressive clips only. For interlaced sources,  you must use appropriate methods (SeparateFieds, SelectEven,SelectOdd, Bob, etc).
  3. Block sizes must be mod 2.
  4. Tested with Avisynth 2.5.6.
  5. Not assembler optimized, but quite fast (itself).
  6. Blending mode with kernel=0 is the same as  Avisynth command Overlay with opacity=0.5.  In this mode the filter can not remove all block artifactes, but it halve them, try use some additional deblock filter.
  7. Mode kernel=1.0 effectively smoothes blocks, but can produce some dot (circle) artefactes instead.

Sample script for overlapped motion compensation

loadplugin("BlockOverlap.dll")
loadplugin("MVTools.dll")

function MVOverlap(clip source, int "blksize", float "kernel", bool "isb", int "lambda", bool "chroma", int "delta", int "thSCD1") 
{
# Overlapped block motion compensation by shifted clips processing and windowed blending  
# Fizick, 2005
# Uses BlockOverlap plugin by Fizick 
# Uses MVTools plugin by Manao
# source clip must have YV12 format,
# all other parameters are optional
	blksize=default(blksize,8)
	kernel=default(kernel,0.5)
	isb = default(isb,false) # backward compensation?
	lambda=default(lambda,2000) # vector smooth
	chroma=default(chroma,false) # use chroma
	delta=default(delta,1) # frame step
	thSCD1=default(thSCD1,300) # scenechange threshold
	add = (blksize>=8) ? blksize : 8
	vec = source.MVAnalyse(blksize=blksize, isb = isb, lambda = lambda, chroma=chroma, delta=delta)
	comp = source.MVCompensate(vec,thSCD1=thscd1)
	shifted = source.addborders(blksize/2,blksize/2,add-blksize/2,add-blksize/2) # diagonal shift by half of block
	vecshifted = shifted.MVAnalyse(blksize=blksize, isb = isb, lambda = lambda, chroma=chroma, delta=delta)
	compshifted = shifted.MVCompensate(vecshifted, thSCD1=thscd1)
	compshiftedback = compshifted.crop(blksize/2,blksize/2,blksize/2-add,blksize/2-add) # remove shifting borders
	ov = BlockOverlap(comp,compshiftedback,xblksize=blksize, yblksize=blksize, kernel=kernel)
	return ov
}

avisource("video.avi")
src=ConvertToYV12(interlaced=false) # progressive clip example
blksize=8
MVOverlap(src, blksize, 0.5, false, 1000, true, 1, 500) #  forward overlapped motion compensation

Sample script for overlapped motion compensated strong denoising

loadplugin("BlockOverlap.dll")
loadplugin("MVTools.dll")

# use the same MVOverlap function as above  
# ... put it here 

loadplugin("degraimedian.dll") # if you use it
loadplugin("fft3dfilter.dll")  # if you use it

AviSource("video.avi")
src=ConvertToYV12(interlaced=false) # progressive clip example
fo = MVOverlap(src, blksize=8, kernel=0.5, isb=false) # forward overlapped motion compensation
bo = MVOverlap(src, blksize=8, kernel=0.5, isb=true) # backward overlapped motion compensation
Interleave(fo,src,bo)  # 3-length interleaved clip, every source has 2 motion compensated neigbours
  DegrainMedian(mode=0) # use any temporal 3-frames denoising filter (FluxSmoothT, Despot, etc)
  fft3dfilter(sigma=2.0) # or more filters
SelectEvery(3,1) # get filtered result

License

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 as published by
the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

Please consider to make some donation to be registered user.

Version changes:

Download BlockOverlap version 0.2

Return to main page