H.261 Datasheet, PDF (8/31 Pages) List of Unclassifed Manufacturers – LINE TRANSMISSION OF NON-TELEPHONE SIGNALS

V id e o
in
CC
T
p
t
qz
Q
q
Q^{- 1}
T ^-1
T o vide o
m ultip lex
co de r
F
P
T T ra ns fo rm
Q Q ua n tizer
P P ictu re m e m or y with m o tio n com p en sa te d variab le de lay
F L o op f ilte r
C C C o d in g co nt ro l
p F la g fo r IN T R A /IN T E R
t
F la g fo r tr an sm itte d o r no t
q z Q ua n tizer in d ic atio n
q Q ua n tizing in de x f or t ra n sfo rm coe ff icie n ts
v M o tio n v ect or
f
S w itch in g o n/ off o f t he lo op f ilte r
FIGURE 3/H.261...[D03] = 16 CM
FIGURE 3/H.261
Source coder
v
f
T 150 24 41-9 0/d0 3
3.2.3 Loop filter
The prediction process may be modified by a two-dimensional spatial filter (FIL) which operates on pels within a predicted 8
by 8 block.
The filter is separable into one-dimensional horizontal and vertical functions. Both are non-recursive with coefficients of 1/4,
1/2, 1/4 except at block edges where one of the taps would fall outside the block. In such cases the 1-D filter is changed to
have coefficients of 0, 1, 0. Full arithmetic precision is retained with rounding to 8 bit integer values at the 2-D filter output.
Values whose fractional part is one half are rounded up.
Recommendation H.261 (03/93)
5