ADV7182ABCPZ datasheet(55/102 Pages) AD

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Data Sheet

ADV7182A

Rev. 0 | Page 55 of 102

Table 82. Ancillary Data in Byte Output Format1

Byte

Description

Ancillary data preamble

I2C_DID6_2[4:0]

DID

I2C_SDID7_2[5:0]

SDID

DC[4:0]

Data count

Padding[1:0]

VBI_DATA_STD[3:0]

ID0 (User Data-Word 1)

LINE_NUMBER[9:5]

ID1 (User Data-Word 2)

EVEN_FIELD

LINE_NUMBER[4:0]

ID2 (User Data-Word 3)

VDP_TTXT_TYPE[1:0]

ID3 (User Data-Word 4)

VBI_WORD_1[7:0]

ID4 (User Data-Word 5)

VBI_WORD_2[7:0]

ID5 (User Data-Word 6)

VBI_WORD_3[7:0]

ID6 (User Data-Word 7)

VBI_WORD_4[7:0]

ID7 (User Data-Word 8)

VBI_WORD_5[7:0]

ID8 (User Data-Word 9)

Pad 0x200; these

padding words may be

present, depending on

ancillary data type; user

data-word

n − 3

n − 2

n − 1

Checksum

CS (checksum word)

1 This mode does not fully comply with ITU-R BT.1364.

Structure of VBI Words in the Ancillary Data Stream

Each VBI data standard is 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 83 shows the format of VBI_WORD_x in the

ancillary data stream.

Table 83. Structure of VBI Data-Words in the Ancillary Stream

Ancillary Data Byte No.

Byte Type

Description

VBI_WORD_1

FC0

Framing Code[23:16]

VBI_WORD_2

FC1

Framing Code[15:8]

VBI_WORD_3

FC2

Framing Code[7:0]

VBI_WORD_4

DB1

First data byte

…

VBI_WORD_N + 3

DBn

Last (nth) data byte

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 bits available in ID0 (UDW 1). The framing

code is always reported in the inverse transmission order.

Table 84 shows the framing code and its valid length for VBI

data standards supported by VDP.

Example

For teletext (B-WST), the framing code byte is 11100100 (0xE4),

with bits shown in the order of transmission. VBI_WORD_1 =

0x27, VBI_WORD_2 = 0x00, and VBI_WORD_3 = 0x00

translated into UDWs in the ancillary data stream for nibble

mode are as follows:



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)

For byte mode,



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)

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