VPC3233D datasheet(15/78 Pages) MICRONAS

15 / 78 page

ADVANCE INFORMATION

VPC 323xD, VPC 324xD

Micronas

2.4.5. 4:4:4 to 4:2:2 Downsampling

After the mixer, the 4:4:4 YCrCb_mix data stream is

downsampled to the 4:2:2 format. For this sake, a

chroma lowpass filter is provided to eliminate high-fre-

quency components above 5-6 Mhz which may typi-

cally be present on inserted high resolution RGB/

YCrCb sources.

In case of main video processing (loopthrough) only, it

is recommended to bypass this filter by using the I2C

bit CIPCFBY.

2.4.6. Fast Blank and Signal Monitoring

The analogue Fast Blank state is monitored by means

of four I2C readable bits. These bits may be used by

the TV controller for SCART signal ident:

– FBHIGH: set by FB high, reset by register read at

FB low

– FBSTAT: FB status at register read

– FBRISE: set by FB rising edge, reset by register

read

– FBFALL: set by FB falling edge, reset by register

read

Fig. 2–11: Fast Blank Monitor

An additional monitoring bit is also provided for the

RGB/YCrCb signal; it indicates whether the ADCs

inputs are clipped or not. In case of clipping conditions

(1Vpp RGB input for example) the ADC range can be

extended by 3db by using the XAR bit.

– CLIPD: set by RGB/YCrCb input clip, reset by regis-

ter read

2.5. Horizontal Scaler

The 4:2:2 YCrCb signal from the mixer output is pro-

cessed by the horizontal scaler. It contains a lowpass-

filter, a prescaler, a scaling engine and a peaking filter.

The scaler block allows a linear or nonlinear horizontal

scaling of the input signal in the range of 1/32 to 4.

Nonlinear scaling, also called “panorama vision”, pro-

vides a geometrical distortion of the input picture. It is

used to fit a picture with 4:3 format on a 16:9 screen by

stretching the picture geometry at the borders. Also,

the inverse effect - called water glass - can be pro-

duced by the scaler. A summary of scaler modes is

given in Table 2–3.

2.5.1. Horizontal Lowpass-filter

The luma filter block applies anti-aliasing lowpass fil-

ters. The cutoff frequencies are selectable and have to

be adapted to the horizontal scaling ratio.

Table 2–2: CIP softmixer modes

I2C

CIP

mode

SELLIN

RGB

DLY

FBCLP

MODE

Force

YCrCb

main

00x

Force

RGB/

YCrCb

00x

Static

Mixer

001

Linear

000

FB non-

Linear

110

<27>FBLHIGH

<27>FBLFALL

<27>FBLRISE

<27>FBLSTAT

reading I2C

analog fast

blank input

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