adv7180 Analog Devices, Inc., adv7180 Datasheet - Page 55

• Manufacturer Part Number: adv7180
• Description: 10-bit, 4 X Oversampling Sdtv Video Decoder
• Manufacturer: Analog Devices, Inc.

Table 71. Ancillary Data in Byte Output Format
Byte
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
.
.
.
n − 3
n − 2
n − 1
1
Structure of VBI Words in Ancillary Data Stream
Each VBI data standard has been split into a clock-run-in
(CRI), a framing code (FC), and a number of data bytes (n).
The data packet in the ancillary stream includes only the FC
and data bytes. Table 72 shows the format of the VBI_WORD_x
in the ancillary data stream.
Table 72. Structure of VBI Data-Words in Ancillary Stream
Ancillary Data
Byte Number
VBI_WORD_1
VBI_WORD_2
VBI_WORD_3
VBI_WORD_4
…
VBI_WORD_N + 3
VDP Framing Code
The length of the actual framing code depends on the VBI data
standard. For uniformity, the length of the framing code
reported in the ancillary data stream is always 24 bits. For
standards with a smaller framing code length, the extra LSB bits
are set to 0. The valid length of the framing code can be
decoded from the VBI_DATA_STD bit available in ID0
(UDW 1). The framing code is always reported in the inverse-
transmission order.
Table 73 shows the framing code and its valid length for VBI
data standards supported by VDP.
This mode does not fully comply with ITU-R BT.1364.
B9
0
1
1
EP
EP
EP
EP
EP
EP
EP
.
.
.
1
1
B8
B8
0
1
1
EP
EP
EP
EP
EP
EP
EP
.
.
.
0
0
Byte Type
FC0
FC1
FC2
DB1
…
DBn
B7
0
1
1
0
0
padding[1:0]
0
Even_Field
0
.
.
.
0
0
Framing code [23:16]
Framing code [15:8]
1
…
Last (n
Description
Framing code [7:0]
st
data byte
VBI_WORD_1[7:0]
VBI_WORD_2[7:0]
VBI_WORD_3[7:0]
VBI_WORD_4[7:0]
VBI_WORD_5[7:0]
B6
0
1
1
0
.
.
.
0
0
th
) data byte
1
Checksum
I
B5
0
1
1
0
.
.
.
0
0
2
C_SDID7_2[5:0]
Line_number[9:5]
Line_number[4:0]
Rev. B | Page 55 of 112
I
2
C_DID6_2[4:0]
B4
0
1
1
0
.
.
.
0
0
VBI_DATA_STD[3:0]
DC[4:0]
B3
0
1
1
VDP_TTXT_TYPE[1:0]
.
.
.
0
0
Example
For teletext (B-WST), the framing code byte is 11100100
(0xE4), with bits shown in the order of transmission. For
VBI_WORD_1 = 0x27, VBI_WORD_2 = 0x00, and
VBI_WORD_3 = 0x00 translated into UDWs in the ancillary
data stream for nibble mode is as follows:
For byte mode:
UDW5 [5:2] = 0010
UDW6 [5:2] = 0111
UDW7 [5:2] = 0000 (undefined bits set to 0)
UDW8 [5:2] = 0000 (undefined bits set to 0)
UDW9 [5:2] = 0000 (undefined bits set to 0)
UDW10 [5:2] = 0000 (undefined bits set to 0)
UDW5 [9:2] = 0010_0111
UDW6 [9:2] = 0000_0000 (undefined bits set to 0)
UDW7 [9:2] = 0000_0000 (undefined bits set to 0)
B2
0
1
1
.
.
.
0
0
B1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
.
.
.
0
0
0
0
B0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
.
.
.
0
0
0
Description
Ancillary data preamble.
DID.
SDID.
Data count.
ID0 (User Data-Word 1).
ID1 (User Data-Word 2).
ID2 (User Data-Word 3).
ID3 (User Data-Word 4).
ID4 (User Data-Word 5).
ID5 (User Data-Word 6).
ID6 (User Data-Word 7).
ID7 (User Data-Word 8).
ID8 (User Data-Word 9).
Pad 0x200. These
padding words may be
present depending on
ancillary data type. User
data-word xx.
CS (checksum word).
ADV7180