ADV7181 AD [Analog Devices], ADV7181 Datasheet - Page 55

• Manufacturer Part Number: ADV7181
• Description: Multiformat SDTV Video Decoder
• Manufacturer: AD [Analog Devices]

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.
Rev. 0 | Page 55 of 96
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]
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Line Number
(ITU-R BT.470)
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
273 (10)
274 (11)
275 (12)
276 (13)
277 (14)
278 (15)
279 (16)
280 (17)
281 (18)
282 (19)
283 (20)
284 (21)
285 (22)
286 (23)
287 (24)
288 (25)
Enable Bit
GDECOL[0]
GDECOL[1]
GDECOL[2]
GDECOL[3]
GDECOL[4]
GDECOL[5]
GDECOL[6]
GDECOL[7]
GDECOL[8]
GDECOL[9]
GDECOL[10]
GDECOL[11]
GDECOL[12]
GDECOL[13]
GDECOL[14]
GDECOL[15]
GDECEL[0]
GDECEL[1]
GDECEL[2]
GDECEL[3]
GDECEL[4]
GDECEL[5]
GDECEL[6]
GDECEL[7]
GDECEL[8]
GDECEL[9]
GDECEL[10]
GDECEL[11]
GDECEL[12]
GDECEL[13]
GDECEL[14]
GDECEL[15]
Comment
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar or
closed caption
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar or
closed caption
Gemstar
Gemstar
Gemstar
Gemstar
ADV7181B