Datasheet

ADV7189B
Rev. B | Page 57 of 104
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 a bit to 1 enables the decoder
block to retrieve Gemstar or closed caption-compatible data on
that particular line. Setting a bit to 0 prevents the decoder from
trying to retrieve data. See
241HTable 74 and 242HTable 75.
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
243HTable 74 and
244HTable 75.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 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 the value
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:
•
Insert all data straight into the data stream, even the reserved
values of 0x00 and 0xFF, if they occur. This can 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 (default), the data is split into half-bytes
and inserted.
When GDECAD is 1, the data is output straight in 8-bit format.
Table 74. NTSC Line Enable Bits and Corresponding Line
Numbering
Line[3:0]
Line Number
(ITU-R BT.470) Enable Bit Comment
0 10 GDECOL[0] Gemstar
1 11 GDECOL[1] Gemstar
2 12 GDECOL[2] Gemstar
3 13 GDECOL[3] Gemstar
4 14 GDECOL[4] Gemstar
5 15 GDECOL[5] Gemstar
6 16 GDECOL[6] Gemstar
7 17 GDECOL[7] Gemstar
8 18 GDECOL[8] Gemstar
9 19 GDECOL[9] Gemstar
10 20 GDECOL[10] Gemstar
11 21 GDECOL[11]
Gemstar or
closed caption
12 22 GDECOL[12] Gemstar
13 23 GDECOL[13] Gemstar
14 24 GDECOL[14] Gemstar
15 25 GDECOL[15] Gemstar
0 273 (10) GDECEL[0] Gemstar
1 274 (11) GDECEL[1] Gemstar
2 275 (12) GDECEL[2] Gemstar
3 276 (13) GDECEL[3] Gemstar
4 277 (14) GDECEL[4] Gemstar
5 278 (15) GDECEL[5] Gemstar
6 279 (16) GDECEL[6] Gemstar
7 280 (17) GDECEL[7] Gemstar
8 281 (18) GDECEL[8] Gemstar
9 282 (19) GDECEL[9] Gemstar
10 283 (20) GDECEL[10] Gemstar
11 284 (21) GDECEL[11]
Gemstar or
closed caption
12 285 (22) GDECEL[12] Gemstar
13 286 (23) GDECEL[13] Gemstar
14 287 (24) GDECEL[14] Gemstar
15 288 (25) GDECEL[15] Gemstar