VPC3230D datasheet(14/78 Pages) MICRONAS

14 / 78 page

VPC 323xD, VPC 324xD

ADVANCE INFORMATION

Micronas

Table 2–1 gives the picture settings achieving exact

level

matching

between

the

YCrCb_cip

and

YCrCb_main channel.

Note: R, G, B, Cr, Cb, = 0.7 Vpp, Y(+ sync) 1 Vpp

2.4.4. Softmixer

After an automatic delay matching, the component sig-

nals and the upsampled main video signal are gath-

ered onto a unique YCrCb channel by means of a ver-

satile 4:4:4 softmixer (see also Fig. 2–10).

The softmixer circuit consists of a Fast Blank (FB) pro-

cessing block supplying a mixing factor k (0...64) to a

high quality signal mixer achieving the output function:

YCrCb_mix=( k*YCrCb_main+ (64-k)*YCrCb_cip )/64

The softmixer supports several basic modes that are

selected via I2C bus (see Table 2–2).

2.4.4.1. Static Switch Mode

In its simplest and most common application the soft-

mixer is used as a static switch between YCrCb_main

and YCrCb_cip. This is for instance the adequate way

to handle a DVD component signal.

The factor k is clamped to 0 or 64, hence selecting

YCrCb_main or the component input YCrCb_cip. (see

Table 2–2)

2.4.4.2. Static Mixer Mode

The signal YCrCb_main and the component signal

YCrCb_cip may also be statically mixed. In this envi-

ronment, k is manually controlled via I2C registers

FBGAIN and FBOFFS according to the following

expression:

k = FBGAIN*(31

−FBOFFS) + 32

All the necessary limitation and rounding operation are

built-in to fit the range: 0

≤ k ≤ 64.

In the static mixer mode as well as in the previously

mentioned static switch mode (see Table 2–2), the

softmixer operates independently of the analogue Fast

Blank input.

2.4.4.3. Dynamic Mixer Mode

In the dynamic mixer mode, the mixer is controlled by

the Fast Blank signal. The VPC32xxD provides a linear

mixing coefficient

k=kl = FBGAIN*(FB

−FBOFFS) + 32

(FB is the digitized Fast Blank), and a non-linear mix-

ing coefficient knl=F(kl), which results from a further

non-linear processing of kl.

While the linear mixing coefficient is used to insert a

fullscreen video signal, the non-linear coefficient is

well-suited to insert Fast Blank related signals like text.

The non-linear mixing reduces disturbing effects like

over/undershoots at critical Fast Blank edges.

Fig. 2–10: Block diagram of the component mixer

Table 2–1: Standard picture settings

input

format

contrast

brightness

satCr

satCb

RGB

YCrCb

Y/C processing

mixer

Component

Processing

VIDEO

RGB/YCrCb

YCrCb_main

YCrCb_cip

YCrCb_mix

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