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.
•
Data count byte, giving the number of user data-words that
follow.
•
•
User data section.
Entries within the packet are as follows:
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).
•
•
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).
•
Checksum byte.
Table 82 lists the values within a generic data packet that is
output by the ADV7180 in 8-bit format.
•
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.
DATA IDENTIFICATION
SECONDARY DATA IDENTIFICATION
DATA
COUNT
OPTIONAL PADDING CHECK
00
FF
FF
DID
SDID
USER DATA
BYTES
SUM
PREAMBLE FOR ANCILLARY DATA
USER DATA (4 OR 8 WORDS)
Figure 47. Gemstar and CCAP Embedded Data Packet (Generic)
Table 82. Generic Data Output Packet
Byte
D[9]
D[8]
D[7]
D[6]
D[5]
D[4]
D[3]
D[2]
D[1]
D[0]
0
Description
Fixed preamble
Fixed preamble
Fixed preamble
DID
0
0
0
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
2
1
1
1
1
1
3
0
1
0
1
0
4
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
CS[8]
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
CS[8]
EF
0
2X
0
0
SDID
line[3:0]
5
0
0
DC[1]
word1[7:4]
word1[3:0]
word2[7:4]
word2[3:0]
word3[7:4]
word3[3:0]
word4[7:4]
word4[3:0]
DC[0]
0
Data count (DC)
6
0
0
0
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
7
0
0
0
8
0
0
0
9
0
0
0
10
11
12
13
14
0
0
0
0
0
0
0
0
0
0
0
0
CS[7]
CS[6]
CS[5]
CS[4]
CS[3]
CS[2]
0
Table 83. Data Byte Allocation
Raw Information Bytes
Retrieved from the Video Line
User Data-Words
(Including Padding)
2×
1
1
0
0
GDECAD
Padding Bytes
DC[1:0]
10
01
01
01
4
4
2
2
0
1
0
1
8
4
4
4
0
0
0
2
Rev. A | Page 65 of 112
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