VPC3201C Просмотр технического описания (PDF) - Micronas

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VPC3201C

VPC3205C, VPC3215C Video Processor Family

Micronas 

PRELIMINARY DATA SHEET

VPC 3205C, VPC 3215C

2.6.9. Priority Bus Codec

The VPC data outputs are controlled by the priority bus

interface. This interface allows a maximum of 8 signal

sources to be connected on a common video YCrCb

bus. The 3-bit priority bus signal controls the arbitra-

tion and source switching of the video sources on a

pixel-by-pixel basis. The priority bus makes features

possible, such as

– real time digital PIP insertion

– Teletext/Mixed-mode picture insertion.

In general, each source has its own YCrCb bus

request. This bus request may either be software or

hardware controlled, i.e. a fast blank signal. Data colli-

sion on the bus is avoided by a bus arbiter that pro-

vides the individual bus grant in accordance to the

user defined source priority.

Each master sends a bus request using his individual

priority ID onto the bus and immediately reads back

the bus state. Only in case of a positive arbitration, e.g.

the master reads back his own priority ID, the bus is

granted to the master.

2.7. PAL+ Support

For PAL+, the VPC 321x provides basic helper prepro-

cessing:

– A/D conversion (shared with the existing ADCs)

– mixing with subcarrier frequency

– lowpass filter 2.5 MHz

– gain control by chroma ACC

– delay compensation to composite video path

– helper window (line# identification)

– output at the luma output port

Helper signals are processed like the main video luma

signals, i.e. they are subject to scaling, sample rate

conversion and orthogonalization if activated. The

adaptive comb filter processing is switched off for the

helper lines.

It is expected that further helper processing (e.g. non-

linear expansion, matched filter) is performed outside

the VPC.

2.7.1. Output Signals for PAL+/Color+ Support

For a PAL+/Color+ signal, the 625 line PAL image con-

tains a 16/9 core picture of 431 lines which is in stan-

dard PAL format. The upper and lower 72 lines contain

the PAL+ helper signal, and line 23 contains signalling

information for the PAL+ transmission.

For PAL+ mode, the Y signal of the core picture, which

is during lines 60–274 and 372–586, is replaced by the

orthogonal composite video input signal. In order to fit

the signal to the 8-bit port width, the ADC signal ampli-

tudes are used. During the helper window, which is in

lines 24–59, 275–310, 336–371, 587–622, the demodu-

lated helper is signal processed by the horizontal scaler

and the output circuitry. It is available at the luma output

port. The processing in the helper reference lines 23

and 623 is different for the wide screen signaling part

and the black reference and helper burst signals. The

code levels are given in detail in Table 2–4, the output

signal for the helper reference line is shown in Fig. 2–11.

Table 2–4: Output signal code levels for PAL/PAL+ signal

Output Signal

Standard YCrCb

(100% Chroma

Luma Outputs Y[7:0]

Output Format Black/Zero

Level

binary

16

CVBS, CrCb

binary

64

Demodulated

signed

0

Helper

Helper WSS

binary

68

Helper black level, offset binary

128

Ref. Burst

Amplitude

Chroma Outputs C[7:0]

Output Format Amplitude

224

149 (luma)

±109

offset binary

signed

offset binary

signed

–

128±112

±112

128±112

±112

–

149 (WSS:106) –

–

19 (128–109) –

–

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