id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
321	mismatch between HM and WD on ALF chroma coeff prediction	Tomohiro Ikai	wjhan	"There are inconsistency between HM and WD on ALF chroma prediction.

HM's prediction properly works assuming that ""sum of ALF coeff is equal to or near to 1.0"", so WD should follows HM with the following fixs.


(1) fix1
replace
cC[ i ] = 255 – sum – alf_coeff_chroma[ i ]		(8 468)
with
cC[ i ] = 256 – sum – alf_coeff_chroma[ i ]		(8 468)

(2) fix2
replace

sum = alf_coeff_chroma[ AlfCodedLengthChroma – 2 ] + sigma_j( alf_coeff_chroma[ j ] << 1 ) 	(8 469)
with j = 0..AlfCodedLengthChroma – 3

with

sum = sigma_j ( alf_coeff_chroma[ j ] << 1 ) 	(8 469)
with j = 0..AlfCodedLengthChroma – 2



The corresponding function is
TComAdaptiveLoopFilter::predictALFCoeffChroma
"	defect	closed	minor		Text	WD5 (G1103) d9	fixed		bbross wjhan jct-vc@…