SAA4970T View Datasheet(PDF) - Philips Electronics
Part Name
Description
Manufacturer
SAA4970T Datasheet PDF : 32 Pages
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Philips Semiconductors
Economical video processing IC
(ECOBENDIC)
handbook, halfpage
TEST2 1
Pmirref 2
UO 3
VSSA 4
VO 5
VCC 6
YO 7
Vref 8
Iref 9
VrefH 10
R1 11
56 XtalI
55 XtalO
54 TEST1
53 CK1
52 VSS
51 CK2
50 UVIN0
49 UVIN1
48 UVIN2
47 UVIN3
46 YIN0
R2 12
45 YIN1
PIP 13
44 YIN2
CLMP 14
43 VSS
SAA4970T
IE 15
42 VDD
WE 16
41 YIN3
RE 17
40 YIN4
VD 18
HD 19
RESET 20
39 YIN5
38 YIN6
37 YIN7
BONE 21
36 AD0
HA 22
VA 23
ALE 24
35 AD1
34 AD2
33 AD3
IT1 25
32 AD4
IT2 26
31 AD5
WRN 27
30 AD6
RDN 28
29 AD7
MGE091
Preliminary specification
SAA4970T
FUNCTIONAL DESCRIPTION
ECO data path
The data path performs the DCTI, peaking, phase
compensation, framing and blanking functions plus colour
reformatting and variable delay of Y to UV at the input and
output of the data path.
DCTI
DCTI is implemented to get a dynamic interpolation of the
low bandwidth U and V signals. First a 2 : 1 linear
interpolation is done, to go from a 4 : 1 : 1 format to a
4 : 2 : 2 format. A second interpolation is done in which the
data path delay is varied on the basis of a function of the
second derivative of the U and V signal (or more precise:
d
dt
{
dU
dt
+
dV
dt
}
).
The
effect
at an edge is that
during the
first half the data path delay is higher than nominal and in
the second half it is lower than nominal. This will make the
edge much steeper. As this second interpolation is done
with the resolution equal to that of the Y samples and also
with a zero DCTI gain a 2 : 1 interpolation is performed, a
4 : 4 : 4 format is obtained.
The DCTI function can be controlled by setting the range
to ±12, ±8, ±6 or ±4 pixels (see Fig.3) or by adjusting the
gain to 0, 1⁄4, 1⁄2 or 1.
An artefact of this processing exists when two edges are
close together in the video. During the second half of the
first edge a delay is chosen that will collect video data
where the second edge is already active. The same is valid
for the second edge. The result of this processing on a
video pulse, which is looking like a hill, is that of a hill with
one or two bumps in it. To prevent this from happening, the
positions where the first derivatives in U and V change
sign, are marked and used to limit the range of the relative
delay. This function is called ‘over the hill protection’. It can
be turned on and off. Figures 5 and 6 show the effect of
the DCTI function with and without ‘over the hill protection’
when applied to a hill-shaped video pulse.
Fig.2 Pin configuration.
1996 Oct 25
6
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