PRODUCT SPECIFICATION
TMC22x5yA
in Figure 10. The last step is to provide a complementary
The TMC22x5yA Comb Filter
Architecture
cross fade between the YCOMB signal and the output of the
complementary bandsplit filter, shown as SIMPLE in Figure
10. The FLAT signal is simply a delayed version of the input
to the comb filter, therefore the sum of Output1 and Output2
will always be equal to the FLAT video input.
The TMC22x5yA, when implementing a line based comb
filter, has a core architecture as shown in Figure 10. The con-
cept of the complementary bandsplit filter is also observed in
the complementary comb filter architecture. It is therefore
possible to adapt between the complementary comb filter
and bandsplit filter without throwing away any of the
original composite video frequency spectrum.
The TMC22x53A comb filter architecture has three taps.
These taps are three consecutive field lines in a line based
comb, three consecutive picture lines in a field based comb,
or lines that are one frame and one field line apart in the
frame based comb. In addition to these different inputs to the
comb filter, NTSC and PAL video signals comb over differ-
ent taps in different architectures, as described in the comb
filter introduction.
The first step in the complementary comb filter is to separate
the high frequency luminance from the chrominance signal.
This combed high frequency luma signal is shown as
YCOMB in Figure 10. The second step is to produce an array
of comb filter error signals that indicate the degree of confi-
dence that theYCOMB signal is just the high frequency luma
and not a combination of high frequency luma and chroma
smeared over the number of lines used in the comb filter. The
signal representing this degree of confidence is termed “K”
The total internal pipeline latency is 1H + 40 pixels for 3 line
comb filters, for all other comb filter and simple decoder
architectures the pipeline latency is 40 pixels.
XLUT
Output1
–
SIMPLE
Input
1H
Bandsplit
COMB
YCOMB
Output2
+
X
Filters
Filter
Simple +/- {k * Ycomb}
1H
K
XLUT
Figure 10. TMC22x5yA Line Based Comb Filter Architecture
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