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ADV7180
Each data packet starts immediately after the EAV code of the
preceding line. Figure 47 and Table 82 show the overall
structure of the data packet.
Entries within the packet are as follows:
Fixed preamble sequence of 0x00, 0xFF, and 0xFF.
Data identification word (DID). The value for the DID
marking a Gemstar or CCAP data packet is 0x140 (10-bit
value).
Secondary data identification word (SDID), which contains
information about the video line from which data was
retrieved, whether the Gemstar transmission was of 1× or
2× format, and whether it was retrieved from an even or
odd field.
Rev. A | Page 65 of 112
Data count byte, giving the number of user data-words that
follow.
User data section.
Optional padding to ensure that the length of the user
data-word section of a packet is a multiple of 4 bytes
(requirement as set in ITU-R BT.1364).
Checksum byte.
Table 82 lists the values within a generic data packet that is
output by the ADV7180 in 8-bit format.
0
00
FF
FF
DID
SDID
DATA
COUNT
USER DATA
OPTIONAL PADDING
BYTES
CHECK
SUM
SECONDARY DATA IDENTIFICATION
PREAMBLE FOR ANCILLARY DATA
DATA IDENTIFICATION
USER DATA (4 OR 8 WORDS)
Figure 47. Gemstar and CCAP Embedded Data Packet (Generic)
Table 82. Generic Data Output Packet
Byte
D[9]
0
0
1
1
2
1
3
0
4
EP
5
EP
6
EP
7
EP
8
EP
9
EP
10
EP
11
EP
12
EP
13
EP
14
CS[8]
D[8]
0
1
1
1
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
CS[8]
D[7]
0
1
1
0
EF
0
0
0
0
0
0
0
0
0
CS[7]
D[6]
0
1
1
1
2X
0
0
0
0
0
0
0
0
0
CS[6]
D[5]
0
1
1
0
D[4]
0
1
1
0
D[3]
0
1
1
0
D[2]
0
1
1
0
D[1]
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
D[0]
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
Description
Fixed preamble
Fixed preamble
Fixed preamble
DID
SDID
Data count (DC)
User data-words
User data-words
User data-words
User data-words
User data-words
User data-words
User data-words
User data-words
Checksum
line[3:0]
0
0
DC[1]
DC[0]
word1[7:4]
word1[3:0]
word2[7:4]
word2[3:0]
word3[7:4]
word3[3:0]
word4[7:4]
word4[3:0]
CS[4]
CS[5]
CS[3]
CS[2]
Table 83. Data Byte Allocation
Raw Information Bytes
Retrieved from the Video Line
2×
1
4
1
4
0
2
0
2
User Data-Words
(Including Padding)
8
4
4
4
GDECAD
0
1
0
1
Padding Bytes
0
0
0
2
DC[1:0]
10
01
01
01