VPC3243D datasheet(17/78 Pages) MICRONAS

17 / 78 page

ADVANCE INFORMATION

VPC 323xD, VPC 324xD

Micronas

Fig. 2–13: Peaking characteristics

2.6. Vertical Scaler

For PIP operation, the vertical scaler compresses the

incoming 4:2:2 YCrCb active video signal in vertical

direction. It supports a vertical compression ratio of

1(= no compression), 2, 3, 4 and 6.

In case of a vertical compression of 2, 4 and 6, the fil-

ter performs the PAL compensation automatically and

the standard PAL delay line should be bypassed (see

2.3.8.).

2.7. Contrast and Brightness

The VPC32xxD provides a selectable contrast and

brightness adjustment for the luma samples. The con-

trol ranges are:

–0

≤contrast ≤63/32

–

−128 ≤ brightness ≤ 127

Note: for ITU-R luma output code levels (16 ... 240),

contrast has to be set to 48 and brightness has to be

set to 16!

2.8. Blackline Detector

In case of a letterbox format input video, e.g. Cinema-

scope, PAL+ etc., black areas at the upper and lower

part of the picture are visible. It is suitable to remove or

reduce these areas by a vertical zoom and/or shift

operation.

The VPC 32xx supports this feature by a letterbox

detector. The circuitry detects black video lines by

measuring the signal amplitude during active video.

For every field the number of black lines at the upper

and lower part of the picture are measured, compared

to the previous measurement and the minima are

stored in the I2C-register BLKLIN. To adjust the picture

amplitude, the external controller reads this register,

calculates the vertical scaling coefficient and transfers

the new settings, e.g. vertical sawtooth parameters,

horizontal scaling coefficient etc., to the VPC.

Letterbox signals containing logos on the left or right

side of the black areas are processed as black lines,

while subtitles, inserted in the black areas, are pro-

cessed as non-black lines. Therefore the subtitles are

visible on the screen. To suppress the subtitles, the

vertical zoom coefficient is calculated by selecting the

larger number of black lines only. Dark video scenes

with a low contrast level compared to the letterbox area

are indicated by the BLKPIC bit.

2.9. Control and Data Output Signals

The VPC 32xx supports two output modes: In

DIGIT3000 mode, the output interfaces run at the main

system clock, in line-locked mode, the VPC generates

an asynchronous line-locked clock that is used for the

output interfaces. The VPC delivers either a YCrCb

4:2:2 or a YCrCb 4:1:1 data stream, each with separate

sync information. In case of YCrCb 4:2:2 format, the

VPC32xxD also provides an interface with embedded

syncs according to ITU-R656.

2.9.1. Line-Locked Clock Generation

An on-chip rate multiplier is used to synthesize any

desired output clock frequency of 13.5/16/18 MHz. A

double clock frequency output is available to support

100 Hz systems. The synthesizer is controlled by the

embedded RISC controller, which also controls all

front-end loops (clamp, AGC, PLL1, etc.). This allows

the generation of a line-locked output clock regardless

of the system clock (20.25 MHz) which is used for

comb filter operation and color decoding. The control

of scaling and output clock frequency is kept indepen-

dent to allow aspect ratio conversion combined with

sample rate conversion. The line-locked clock circuity

generates control signals, e.g. horizontal/vertical sync,

active video output, it is also the interface from the

internal (20.25 MHz) clock to the external line-locked

clock system.

If a line-locked clock is not required, i.e. in the

DIGIT3000 mode, the system runs at the 20.25 MHz

main clock. The horizontal timing reference in this

mode is provided by the front-sync signal. In this case,

the line-locked clock block and all interfaces run from

the 20.25 MHz main clock. The synchronization sig-

nals from the line-locked clock block are still available,

but for every line the internal counters are reset with

the main-sync signal. A double clock signal is not avail-

able in DIGIT3000 mode.

-10

-5

MHz

VPC3243D Datasheet(PDF) 17 Page - Micronas

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