ADV7183B datasheet(21/100 Pages) AD

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ADV7183B

Rev. B | Page 21 of 100

SYNC PROCESSING

The ADV7183B extracts syncs embedded in the video data

stream. There is currently no support for external HS/VS

inputs. The sync extraction has been optimized to support

imperfect video sources such as VCRs with head switches. The

actual algorithm used employs a coarse detection based on a

threshold crossing followed by a more detailed detection using

an adaptive interpolation algorithm. The raw sync information

is sent to a line-length measurement and prediction block. The

output of this is then used to drive the digital resampling

section to ensure the ADV7183B outputs 720 active pixels per

line.

The sync processing on the ADV7183B also includes the

following specialized postprocessing blocks that filter and

condition the raw sync information retrieved from the digitized

analog video.

•

Vsync Processor. This block provides extra filtering of the

detected Vsyncs to give improved vertical lock.

•

Hsync Processor. The Hsync processor is designed to filter

incoming Hsyncs that are corrupted by noise, providing

much improved performance for video signals with stable

time base but poor SNR.

VBI DATA RECOVERY

The ADV7183B can retrieve the following information from the

input video:

•

Wide-screen signaling (WSS)

•

Copy generation management system (CGMS)

•

Closed caption (CC)

•

Macrovision protection presence

•

EDTV data

•

Gemstar-compatible data slicing

The ADV7183B is also capable of automatically detecting the

incoming video standard with respect to

•

Color subcarrier frequency

•

Field rate

•

Line rate

The SPD can configure itself to support PAL-B/G/H/I/D,

PAL-M/N, PAL-combination N, NTSC-M, NTSC-J, SECAM

50 Hz/60 Hz, NTSC4.43, and PAL60.

GENERAL SETUP

Video Standard Selection

The VID_SEL[3:0] bits allows the user to force the digital core

into a specific video standard. Under normal circumstances,

this should not be necessary. The VID_SEL[3:0] bits default to

an autodetection mode that supports PAL, NTSC, SECAM, and

variants thereof. The following section describes the autodetec-

tion system.

Autodetection of SD Modes

To guide the autodetection system, individual enable bits are

provided for each of the supported video standards. Setting the

relevant bit to 0 inhibits the standard from being detected

automatically. Instead, the system picks the closest of the

remaining enabled standards. The results of the autodetection

can be read back via the status registers. See the

169H

Global Status

Registers section for more information.

VID_SEL[3:0] Address 0x00[7:4]

Table 18. VID_SEL Function

VID_SEL

Description

0000 (default)

Autodetect (PAL BGHID) <–> NTSC J

(no pedestal), SECAM

0001

Autodetect (PAL BGHID) <–> NTSC M

(pedestal), SECAM

0010

Autodetect (PAL N) (pedestal) <–> NTSC J

(no pedestal), SECAM

0011

Autodetect (PAL N) (pedestal) <–> NTSC M

(pedestal), SECAM

0100

NTSC-J (1)

0101

NTSC-M (1)

0110

PAL60

0111

NTSC-.43 (1)

1000

PAL-B/G/H/I/D

1001

PAL-N (= PAL BGHID (with pedestal))

1010

PAL-M (without pedestal)

1011

PAL-M

1100

PAL-Combination N

1101

PAL COMBINATION N (with pedestal)

1110

SECAM

1111

SECAM (with pedestal)

AD_SEC525_EN Enable Autodetection of SECAM 525

Line Video, Address 0x07[7]

Setting AD_SEC525_EN to 0 (default) disables the autodetection

of a 525-line system with a SECAM style, FM-modulated color

component.

Setting AD_SEC525_EN to 1 enables the detection.

ADV7183B Datasheet(PDF) 21 Page - Analog Devices

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