5 operating modes, Table 6-62, Sav/eav sequence – AMD Geode LX [email protected] User Manual
Page 402: Table 6-63, Protection bit values
402
AMD Geode™ LX Processors Data Book
Video Processor
33234H
6.7.6.5
Operating Modes
BT.656 Mode
BT.656 is the basic standard that specifies the encoding of
the control lines into the data bus. In this mode the sepa-
rate control lines are encoded into the data bus as speci-
fied by Recommendation ITU-R BT.656.
Each line begins with a Start of Active Video (SAV) header,
and ends with an End of Active Video (EAV) header. Each
of these are four-byte sequences beginning with FF, 00,
00. The fourth byte of the header provides important infor-
mation about this line. The bit format of the SAV and EAV
headers is shown in Table 6-62.
The T bit is specified in BT.656 as a constant logic 1. The F
bit indicates Field - 1 for even (also called Field 2), 0 for
odd (Field 1). The V bit indicates Vertical Blanking. The H
bit indicates Horizontal Blanking. Bits P3 through P0 are
protection bits used to detect and correct single-bit errors.
The bits are defined as follows:
P3 = (V + H) + ~T
P2 = (F + H) + ~T
P1 = (F + V) + ~T
P0 = (F + V) + H
Using the above formulas, the bit values are listed in Table
6-63.
VIP 1.1 Compatible Mode
VIP 1.1 compatible mode builds on CBT.656 mode with the
following changes/additions:
— Video Flags T, F, and V can only be changed in the
EAV code. During vertical blanking there must be a
minimum of one SAV/EAV scan line in order to
convey the updated T, F, and V bits.
— Task bit is used to indicate VBI data within the video
stream (T = 0 for VBI Data, T = 1 for active video).
— P3-P0 are ignored.
Table 6-62. SAV/EAV Sequence
Parameter
D7
D6
D5
D4
D3
D2
D1
D0
Preamble
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Status Word
T
F
V
H
P3
P2
P1
P0
Table 6-63. Protection Bit Values
T
F
V
H
P3
P2
P1
P0
Hex
0
0
0
0
1
1
1
0
0E
0
0
0
1
0
0
1
1
13
0
0
1
0
0
1
0
1
25
0
0
1
1
1
0
0
0
38
0
1
0
0
1
0
0
1
49
0
1
0
1
0
1
0
0
54
0
1
1
0
0
0
1
0
62
0
1
1
1
1
1
1
1
7F
1
0
0
0
0
0
0
0
80
1
0
0
1
1
1
0
1
9D
1
0
1
0
1
0
1
1
AB
1
0
1
1
0
1
1
0
B6
1
1
0
0
0
1
1
1
C7
1
1
0
1
1
0
1
0
DA
1
1
1
0
1
1
0
0
EC
1
1
1
1
0
0
0
1
F1