ADVANCE INFORMATION
VPC 323xD, VPC 324xD
2.3.9. Luminance Notch Filter
2.4. Component Interface Processor CIP
If a composite video signal is applied, the color infor-
mation is suppressed by a programmable notch filter.
The position of the filter center frequency depends on
the subcarrier frequency for PAL/NTSC. For SECAM,
the notch is directly controlled by the chroma carrier
frequency. This considerably reduces the cross-lumi-
nance. The frequency responses for all three systems
are shown in Fig. 2–9.
This block (see Fig. 2–10) contains all the necessary
circuitry dedicated to external analogue components
(YCrCb_cip) such as RGB or YCrCb signals from DVD
players, or other RGB sources with Fast Blank for real
time insertion on the main picture (YCrCb_main).
2.4.1. Component Analogue Front End
dB
10
VPC 32xxD provides two analogue RGB/YCrCb input
ports, one with Fast Blank capability and one without.
0
It is strongly recommended to use analogue 5 MHz
anti-alias low-pass filters on each input, including FB.
While all signals need to be capacitively coupled by
220 nF clamping capacitors, the Fast Blank input
requires DC coupling.
–10
–20
–30
The selected signal channel is further converted into a
digital form by 3 high quality ADCs running at
20.25 MHz with a resolution of 8 bits. The FB input is
digitized with a resolution of 6 bits.
–40
MHz
0
2
4
6
8
10
PAL/NTSC notch filter
Note: The VPC32xxD system synchronization always
occurs through the main CVBS/Y ADC input. In any
component mode, this input must therefore be handled
accordingly.
dB
10
0
–10
2.4.2. Matrix
–20
–30
–40
The RGB signals are converted to the YCrCb format by
a matrix operation:
MHz
0
2
4
6
8
10
Y = 0.299R + 0.587G + 0.114B
(R−Y)= 0.701R − 0.587G − 0.114B
(B−Y)=−0.299R − 0.587G + 0.886B
SECAM notch filter
Fig. 2–9: Frequency responses of the luma
notch filter for PAL, NTSC, SECAM
In case of YCrCb input the matrix is bypassed.
2.3.10. Skew Filtering
2.4.3. Component YCrCb Control
To guarantee optimum mixing results, various I2C pro-
grammable parameters are provided:
The system clock is free-running and not locked to the
TV line frequency. Therefore, the ADC sampling pat-
tern is not orthogonal. The decoded YCrCb signals are
converted to an orthogonal sampling raster by the
skew filters, which are part of the scaler block.
– 0 ≤ contrast ≤63/32
– −128 ≤ brightness ≤ 127
– 0 ≤ saturation Cr ≤ 63/32
– 0 ≤ saturation Cb ≤ 63/32
– −20 ≤ tint ≤ 20 degrees
The skew filters are controlled by a skew parameter
and allow the application of a group delay to the input
signals without introducing waveform or frequency
response distortion.
The amount of phase shift of this filter is controlled by
the horizontal PLL1. The accuracy of the filters is 1/32
clocks for luminance and 1/4 clocks for chroma. Thus
the 4:2:2 YCrCb data is in an orthogonal pixel format
even in the case of nonstandard input signals such as
VCR.
Micronas
13
MICRONAS [ MICRONAS ]
