VPC3230D datasheet(16/78 Pages) MICRONAS

16 / 78 page

VPC 323xD, VPC 324xD

ADVANCE INFORMATION

Micronas

Fig. 2–12: YCrCb downsampling lowpass-filter

2.5.2. Horizontal Prescaler

To achieve a horizontal compression ratio between

1/4 and 1/32 (e. g. for double window or PIP operation)

a linear downsampler resamples the input signal by 1

(no presampling), 2, 4 and 8.

2.5.3. Horizontal Scaling Engine

The scaler contains a programmable decimation filter,

a 1-H FIFO memory, and a programmable interpola-

tion filter. The scaler input filter is also used for pixel

skew correction, see 2.3.10. The decimator/interpola-

tor structure allows optimal use of the FIFO memory. It

allows a linear or nonlinear horizontal scaling of the

input video signal in the range of 0.25 to 4. The con-

trolling of the scaler is done by the internal Fast Pro-

cessor.

2.5.4. Horizontal Peaking-filter

The horizontal scaler block offers an extra peaking fil-

ter for sharpness control. The center frequency of the

peaking filter automatically adopts to the horizontal

scaling ratio. Three center frequencies are selectable

(see Fig. 2–13: )

– center at sampling rate / 2

– center at sampling rate / 4

– center at sampling rate / 6

The filter gain is adjustable between 0 – +10 dB and a

coring filter suppresses small amplitudes to reduce

noise artifacts.

-50

-40

-30

-20

-10

MHz

-50

-40

-30

-20

-10

MHz

Table 2–3: Scaler modes

Mode

Scale

Factor

Description

Compression

4:3

→ 16:9

0.75

linear

4:3 source displayed on

a 16:9 tube,

with side panels

Panorama

4:3

→16:9

non-

linear

compr

4:3 source displayed on

a 16:9 tube,

Borders distorted

Zoom

4:3

→ 4:3

1.33

linear

Letterbox source (PAL+)

displayed on a 4:3 tube,

vertical overscan with

cropping of side panels

Water glass

16:9

→ 4:3

non-

linear

zoom

Letterbox source (PAL+)

displayed on a 4:3 tube,

vertical overscan, bor-

ders distorted, no crop-

ping

20.25

→

13.5 MHz

0.66

sample rate conversion

to line-locked clock

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