ADV7181BBCPZ datasheet(55/96 Pages) AD

55 / 96 page

ADV7181B

Rev. 0 | Page 55 of 96

GDECEL[15:0] Gemstar Decoding Even Lines,

Address 0x48 [7:0]; Address 0x49 [7:0]

The 16 bits of the GDECEL[15:0] are interpreted as a collection

of 16 individual line decode enable signals. Each bit refers to a

line of video in an even field. Setting the bit enables the decoder

block trying to find Gemstar or closed caption-compatible data

on that particular line. Setting the bit to 0 prevents the decoder

from trying to retrieve data. See Table 72 and Table 73.

To retrieve closed caption data services on NTSC (Line 284),

GDECEL[11] must be set.

To retrieve closed caption data services on PAL (Line 335),

GDECEL[14] must be set.

The default value of GDECEL[15:0] is 0x0000. This setting

instructs the decoder not to attempt to decode Gemstar or

CCAP data from any line in the even field.

GDECOL[15:0] Gemstar Decoding Odd Lines, Address 0x4A

[7:0]; Address 0x4B [7:0]

The 16 bits of the GDECOL[15:0] form a collection of 16

individual line decode enable signals. See Table 72 and Table 73.

To retrieve closed caption data services on NTSC (Line 21),

GDECOL[11] must be set.

To retrieve closed caption data services on PAL (Line 22),

GDECOL[14] must be set.

The default value of GDEC0L[15:0] is 0x0000. This setting

instructs the decoder not to attempt to decode Gemstar or

CCAP data from any line in the odd field.

GDECAD Gemstar Decode Ancillary Data Format,

Address 0x4C [0]

The decoded data from Gemstar-compatible transmissions or

closed caption transmissions is inserted into the horizontal

blanking period of the respective line of video. A potential

problem may arise if the retrieved data bytes have the value

0x00 or 0xFF. In an ITU-R BT.656-compatible data stream,

those values are reserved and used only to form a fixed

preamble.

The GDECAD bit allows the data to be inserted into the

horizontal blanking period in two ways:

•

Insert all data straight into the data stream, even the reserved

values of 0x00 and 0xFF, if they occur. This may violate the

output data format specification ITU-R BT.1364.

•

Split all data into nibbles and insert the half-bytes over

double the number of cycles in a 4-bit format.

When GDECAD is 0, the data is split into half-bytes and

inserted (default).

When GDECAD is 1, the data is output straight in 8-bit format.

Table 72. NTSC Line Enable Bits and

Corresponding Line Numbering

line[3:0]

Line Number

(ITU-R BT.470)

Enable Bit

Comment

GDECOL[0]

Gemstar

GDECOL[1]

Gemstar

GDECOL[2]

Gemstar

GDECOL[3]

Gemstar

GDECOL[4]

Gemstar

GDECOL[5]

Gemstar

GDECOL[6]

Gemstar

GDECOL[7]

Gemstar

GDECOL[8]

Gemstar

GDECOL[9]

Gemstar

GDECOL[10]

Gemstar

GDECOL[11]

Gemstar or

closed caption

GDECOL[12]

Gemstar

GDECOL[13]

Gemstar

GDECOL[14]

Gemstar

GDECOL[15]

Gemstar

273 (10)

GDECEL[0]

Gemstar

274 (11)

GDECEL[1]

Gemstar

275 (12)

GDECEL[2]

Gemstar

276 (13)

GDECEL[3]

Gemstar

277 (14)

GDECEL[4]

Gemstar

278 (15)

GDECEL[5]

Gemstar

279 (16)

GDECEL[6]

Gemstar

280 (17)

GDECEL[7]

Gemstar

281 (18)

GDECEL[8]

Gemstar

282 (19)

GDECEL[9]

Gemstar

283 (20)

GDECEL[10]

Gemstar

284 (21)

GDECEL[11]

Gemstar or

closed caption

285 (22)

GDECEL[12]

Gemstar

286 (23)

GDECEL[13]

Gemstar

287 (24)

GDECEL[14]

Gemstar

288 (25)

GDECEL[15]

Gemstar

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