Handbook for Sound Engineers

1136 Chapter 30

pause, a time count decreases ending with zero at the
end of the pause. The absolute time is set to zero at the
beginning of the program area and increases to the start
of the lead-out area. Time and absolute time are
expressed in minutes, seconds, and frames (75 frames
per second). Modes 2 and 3 are optional in the subcode.
The other six channels (R, S, T, U, V, and W,) which
account for about 20 megabytes of 8-bit storage, are

available for other data storage. In some discs, this

capacity is used to hold CD-Text, a feature that was

appended to the original Red Book specification. With

CD-Text, album title, song titles, artist names, and other

text information are coded prior to manufacture.

Compatible players can read and display CD Text infor-

mation and also search for particular album titles in a

changer. CD-Text supports color bitmaps and JPEG

Figure 30-3. CIRC encoding algorithm.

2 2 2 2 2 2 2 2 2 2 2 2

11

1

1

1 1 1 1 1 1 1 1 1 1 1

1

1

4D

5D

6D

7D

8D

9D

16D

17D

18D

19D

20D

21D

22D

23D

24D

25D

26D

27D

C1

encoder

C2

encoder

12

12

28

15D

14D

13D

12D

11D

10D

3D

2D

1D

W W W W W W W W W W W W W W W W W W W W W W W W

L R L R L R L R L R L R P P P P

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

W

Q

Q

Q

Q

2 symbols of 8 bits per word

Two symbol delay

Generation

of 4 parity

symbols

Delay lines of

unequal length

Generation

of 4 parity

symbols

1 symbol

delay

8 bit symbols

to modulator