ADV7180
Table 92. NTSC Line Enable Bits and Corresponding
Line Numbering
GDECAD, Gemstar Decode Ancillary Data Format,
Address 0x4C [0]
Line Number
(ITU-R BT.470)
The decoded data from Gemstar-compatible transmissions or
closed caption-compatible transmission is inserted into the
horizontal blanking period of the respective line of video. A
potential problem can arise if the retrieved data bytes have a
value of 0x00 or 0xFF. In an ITU-R BT.656-compatible data
stream, these 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:
line[3:0]
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]
Comment
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
0
1
2
3
4
5
6
7
8
9
10
11
10
11
12
13
14
15
16
17
18
19
20
21
•
Insert all data straight into the data stream, even the
reserved values of 0x00 and 0xFF, if they occur. This may
violate 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.
Gemstar or
closed caption
0 (default)—The data is split into half-bytes and inserted.
12
13
14
15
0
1
2
3
4
5
6
7
8
9
10
11
22
23
24
25
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]
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
Gemstar
1—The data is output straight into the data stream in 8-bit format.
Table 93. PAL Line Enable Bits and Line Numbering
Line Number
line[3:0] (ITU-R BT.470)
273 (10)
274 (11)
275 (12)
276 (13)
277 (14)
278 (15)
279 (16)
280 (17)
281 (18)
282 (19)
283 (20)
284 (21)
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
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Closed caption
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Not valid
Closed caption
Not valid
12
13
14
15
0
1
2
3
4
5
6
7
8
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
321 (8)
322 (9)
323 (10)
324 (11)
325 (12)
326 (13)
327 (14)
328 (15)
329 (16)
330 (17)
331 (18)
332 (19)
333 (20)
334 (21)
335 (22)
336 (23)
Gemstar or
closed caption
12
13
14
15
285 (22)
286 (23)
287 (24)
288 (25)
GDECEL[12]
GDECEL[13]
GDECEL[14]
GDECEL[15]
Gemstar
Gemstar
Gemstar
Gemstar
9
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
10
11
GDECOL[15:0], Gemstar Decoding Odd Lines,
Address 0x4A [7:0], Address 0x4B [7:0]
The 16 bits of GDECOL[15:0] form a collection of 16 individual
line decode enable signals. See Table 92 and Table 93.
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 GDECOL[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. The user should only
enable Gemstar slicing on lines where VBI data is expected.
Rev. A | Page 70 of 112
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