ADV7181BBCPZ datasheet(20/96 Pages) AD

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ADV7181B

Rev. 0 | Page 20 of 96

SYNC PROCESSING

The ADV7181B 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 videocassette recorders 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 that the ADV7181B outputs

720 active pixels per line.

The sync processing on the ADV7181B 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 have been corrupted by

noise, providing much improved performance for video

signals with stable time base but poor SNR.

VBI DATA RECOVERY

The ADV7181B 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 ADV7181B is also capable of automatically detecting the

incoming video standard with respect to

•

Color subcarrier frequency

•

Field rate

•

Line rate

The ADV7181B can configure itself to support PAL-BGHID,

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] register 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 provides more informa-

tion on the autodetection system.

Autodetection of SD Modes

In order to guide the autodetect system of the ADV7181B,

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 block can be read back via the status

registers. See the Global Status Registers section for more

information.

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

Table 17. VID_SEL Function

VID_SEL[3:0]

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

PAL 60.

0111

NTSC 4.43 (1).

1000

PAL BGHID.

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.

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