ADV7184 Datasheet, PDF (52/108 Pages) Analog Devices – Multiformat SDTV Video Decoder with Fast Switch Overlay Support

ADV7184
The ancillary data packet sequence is explained in Table 69 and
Table 70. The nibble output mode is the default mode of output
from the ancillary stream when ancillary stream output is
enabled. This format is in compliance with ITU-R BT.1364.
Some definitions of the abbreviations used in Table 69 and
Table 70 include:
• EP. Even parity for bits B8 to B2. This means that the parity
bit EP is set so that an even number of 1s are in bits in B8
to B2, including the parity bit, D8.
• CS. Checksum word. The CS word is used to increase
confidence of the integrity of the ancillary data packet
from the DID, SDID, and DC through user data-words
(UDWs). It consists of 10 bits: a 9-bit calculated value and
B9 as the inverse of B8. The checksum value B8 to B0 is
equal to the 9 LSBs of the sum of the 9 LSBs of the DID,
SDID, and DC and all UDWs in the packet. Prior to the
start of the checksum count cycle all checksum and carry
bits are pre-set to zero. Any carry resulting from the
checksum count cycle is ignored.
• EP. The MSB B9 is the inverse EP. This ensures that
restricted codes 0x00 and 0xFF do not occur.
• Line_number [9:0]. The line number of the line that
immediately precedes the ancillary data packet. The line
number is as per the numbering system in ITU-R BT.470.
The line number runs from 1 to 625 in a 625 line system
and from 1 to 263 in a 525 line system. Note the line
number on which the packet is output differs from the line
number on which the VBI data was sliced due to the
vertical delay through the comb filters.
• Data Count. The data count specifies the number of
UDWs in the ancillary stream for the standard. The total
number of user data-words = 4 × Data Count. Padding
words may be introduced to make the total number of
UDWs divisible by four.
Table 69. Ancillary Data in Nibble Output Format
Byte
B9 B8
B7
B6
B5
0
0
0
0
0
0
1
1
1
1
1
1
2
1
1
1
1
1
B4 B3
0
0
1
1
1
1
B2
B1
0
0
1
1
1
1
3
EP
EP
0
I2C_DID6_2[4:0]
0
4
EP
EP
I2C_SDID7_2[5:0]
0
5
EP
EP
0
DC[4:0]
0
6
EP
EP
padding[1:0]
VBI_DATA_STD[3:0]
0
7
EP
EP
0
Line_number[9:5]
0
8
EP
EP
Even_Field
Line_number[4:0]
0
9
EP
EP
0
0
0
0
VDP_TTXT_TYPE[1:0] 0
10
EP
EP
0
0
VBI_WORD_1[7:4]
0
11
EP
EP
0
0
VBI_WORD_1[3:0]
0
12
EP
EP
0
0
VBI_WORD_2[7:4]
0
13
EP
EP
0
0
VBI_WORD_2[3:0]
0
14
EP
EP
0
0
VBI_WORD_3[7:4]
0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
n-3
1
0
0
0
0
0
0
0
0
n-2
1
0
0
0
0
0
0
0
0
n-1
B8
Checksum
0
B0
Description
0
1
Ancillary data preamble
1
0
DID (data identification
word)
0
SDID (secondary data
identification word)
0
Data count
0
ID0 (user data-word 1)
0
ID1 (user data-word 2)
0
ID2 (user data-word 3)
0
ID3 (user data-word 4)
0
User data-word 5
0
User data-word 6
0
User data-word 7
0
User data-word 8
0
User data-word 9
.
[Pad 0x200. These
.
padding words may or
.
may not be present
depending on ancillary
0
data type.] User data-
0
word XX
0
CS (checksum word)
Rev. 0 | Page 52 of 108