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AUX:
--on
the A727 the four bits designated as AUX are
always
"zero', On other units they
~an
contain supplementary in-
formation
or be used for expanding the audio information
to 24 bits,
AUDIO SAMPLE
~ORD:
The
audio information is always transmitted as
linear
two's
complements
with
the
most
significant
bit
in
pOSition
27,
If fewer than 20 bits
are
required,
the
excess bits are set to "zero· _ On the A727 bits
8
through
11 are always "zero·,
VALIDITY FLAG:
ThE
VALIDITY ,LAG
is
normally "0".
When it is
set
to
"1"
this means that the entire SUBFRAME is invalid,
For
interpolation
of the
error correction and muting,
this
flag
is "'".
It
is
only 'zero" when all errors are
100X
correctable.
"Un-channel:
On the
"U"-cha~nel
(user channel) a 5ubcode block
com-
prising
up
to 1176 bits (12 • 98) is
transmitted with
each SU8fRAME.
A
5ubcode block starts with a synchronization word
con-
taining at Least 16 "zero" bits. The data bits (in the
CO
form~t
these are the 7 bits
Q,
R, 5,
T,
U,
V,
and
W)
are
always preceded by a start bit,
log.
"1".
The distance
between
twO
start bits may not be less than 8 bits and no
more than 16 bits, Excess bits are filled with "zero"_
"C"-channel:
On
the "CO-channel (channel status),
one bit of an up
to 192 bit long word is transmitted with each SUBFRAME.
The
first
bit of this word (bit 0) is in
the
SUS,RAME
with the SYNC PREAMSLE "S" (block start).
The
first four bits <bits 0 through 3) contain the
~on
trol information,
a copy of the four control bits of the
Q-channel,
aits 4 through 7 are not used and contain al-
ways
"zero".
Bit$ 8 through 15 contain the CO
category
cou~
Bit
8
is always "1" and all
r-~maining
bits
are
"zero" .
Bi ts 16 through 191 ar e not used at current
and
always •
~~r·o".
The
control information of the Q-channeL (bit
a
through
3) is defined
In
the CO standard
and
depends on the disc:
BH
:0
123
Description
o a
x
0
2-channe
l audio without preemphasis
o a
x
2-channel audiO with pree'Qhasis
lOX
X
Reser
ved for 4-channeL audio
o
1 X 0
Digital dato
°
1 X 0
Reserved
1 1 X X
Reserved
X X
°
X
Digital copy prohibited
X X 1 X
Digital copy permitt
ed
PARITY BIT:
A PARITY BrT is generated and transmitted for detecting
errors in the
transmi~5ion.
The PARITY
811
is Logic "0" when the
number
of
bits
transmitted as logic "1" (bits 4 through 30) is even,
A727
Example of 2-channel Compact Disc format
--
-
_.
I
M
Nr. SYN AUX
AUOIO SAMPLE
S
8
1
8
0000 0000 xxxx xxxx xxxx XXXX
2
1,1
0000 0000 xxxx xxxx xxxx xxxx
3
M
0000 0000 xxxx xxxx xxxx xxxx
4
I.'
0000 0000 xxxx XXXX XXXX xxxx
5
M
0000 0000 XXXX XXXX xxxx xxxx
6
w
0000 0000 xxxx xxxx xxxx xxxx
7
M
0000 0000 XXXX XXXX XXXX XXXX
8
w
0000 0000 XXXX XXXX XXXX XXXX
'1
'1
0000 0000 xxxx xxxx xxxx XXXX
10
vi
0000 0000 XXXX XXXX XXXX XXXX
11
M
0000 0000 XXXX xxxx XXXX XXXX
12
w
0000 0000 XXXX XXXX XXXX XXXx
-
,--
13
M
0000 0000 xxxx xxxx XXXX XXXX
14
w
0000 0000 XXXX XXXX XXXX xxxx
15
M 0000 0000 XXXX XXXX xxxx XXXX
16
W
:1000 0000 xxxx XXXX XXXX xxxx
17
M 0000 0000 XXXx XXXX XXXX XXXX
18
w
0000 0000 XXXX XXXX xxxx xxxx
19
M
0000
0000 xxxx
xxxx
XXXX XXXX
20
w 0000 0000 xxxx XXXX XXXX XXXX
21
M
0000
0000
xxxx xxxx xxxx XXXX
22
W
0000 0000 XXXX XXXX XXXX XXXX
23
M
0000 0000 XXXX XXXX xxxx XXXX
24
W
0000
0000
XXXX XXXX xxxx XXXX
- -
2S
M 0000
0000
xxxx xxxx xxxx XXXX
26
w
0000
0000
xxxx XXXX xxxx xxxx
27
M
0000
0000 XXXX xxxx xxxx XXXX
28
w 0000
0000
XXXX XXXX xxxx xxxx
29
,' 1
0000
0000
xxxx
xxxx
xxxx xxxx
30
w 0000 0000 XXXX XXXX XXXX XXXX
3-
M 0000
0000
xxxx
XXXX
xxxx xxxx
32
1.,'
0000
0000
XXXX xxxx XXXX xxxx
33
lot
0000
0000 xxxx xxxx XXXX xxxx
3£.
I.'
0000
0000 XXXX XXXX
XXXX
XXXX
3S
M
0000 0000 xxxx XXXX xxxx xxxx
36
I.'
0000 0000 XxXx XXXx XXXX xxxx
37
M 0000 0000 XXxX XXXX XXXX xxxx
38
1,1
0000
0000 xxxx XXXX xxxx XXXX
:w
M
0000
0000
xxxx XXXX xxxx xxxx
£.0
' "
0000 0000 xxxx XXXX xxxx xxxx
41
,..,
0000 0000 xxxx XXxX XXXX XXXX
£.2
~I
.
JOOO 0000 XXXX XXXX XXXX xxxx
43
M
0000 0000 XXXX XXXX XXXx xxxx
44
W
0000 0000 xxxx xxxx xxxx xxxx
4S
M
0000
0000 xxxx XXXX XXXX xxxx
46
W
0000 0000 XXXX XXXX XXXX xxxx
L.7
H
0000 0000 XXXx xxxx XXXX xxxx
48
w
0000 0000 XXXX XXXX xxxx XXXX
I
I
I
J
I
373
I
I
M 0000 0000 xxxx XXXX XXXX
I
XXXX
374
37
5
376
377
378
379
380
381
382
383
384
W 0000 0000
M 0000 0000
W 0000
0000
M 0000 0000
W 0000 0000
M 0000 0000
W 0000 0000
0000 0000
w
10000 0000
M
0000
0000
w
0000 0000
xxxx xxxx xxxx
xxxx XXXX XXXX
XXXX xxxx xxxx
XXXX xxxx XXXX
XXxx xxxx xx xx
XXXX XXXx XXXX
XXXX XXXX xxxx
XXXX XXXX XXXX
xxxx XXXX XXXX
xxxx xxxx xxxx
XXXX xxxx XXXx
xxxx
xxxx
XXXX
XXXX
xxxx
XXXX
XXXX
XXXX
xxxx
xxxx
XXXX
1
B
2
VI
3
M
4
W
S
M
0000 0000
XXXX
XXXX XXXX xxxx
0000 0000 xxxx XXXX xxxx xxxx
0000 0000
XXXX
XXXX XXXX XXXX
0000 0000 xxxx xxxx xxxx XXXX
0000 0000 XXXX XXXX xxxx xxxx
V
U
a
0
a
a
a
a
a
a
a
0
0
0
0
0
0
0
0
0
a
a
0
a
0
0
0
0
G
0
0
0
0
0
0
0
0
a
0
0
a
0
0
0
0
a
0
a
a
0
0
1
0
Q1
0
R1
a
S1
a
T1
a
U1
a
V1
0
W1
0
0
0
a
0
a
0
0
0
1
0 112
0
R2
a -,?
0 T2
a
u2
a
v2
a
1,12
a
0
a
0
0
0
0
0
I
a
1
a
Q30
0
R30
0
530
0
no
0
U50
a
v30
a
1<30
0
0
0
0
a
0
0
0
o
1
o
Q31
o
R31
o
S31
o ;
T31
C
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