Handbook for Sound Engineers

1150 Chapter 30

use the front L and R channels, front L, R and C chan-
nels, and the corner L, R, Ls, and Rs channels. The
sampling frequency and word length of CG1 is greater
than or equal to those of CG2. Generally, CG1 assign-
ments are for front channels, and CG2 assignments are
for rear channels. Channels can be assigned as groups of
mono to six channels, and different word lengths and
front and rear channels can use different sampling
frequencies. For example, to reduce storage require-
ments, front channels could be coded at 24/96 and the
rear channels coded at 16/48. The sampling frequencies
must be related by a simple integer such as
48/96/192 kHz or 44.1/88.2/176.4 kHz.
Audio content can vary considerably. For example, a
disc might use stereo LPCM audio for its selections.
Another disc might contain one selection coded as
multichannel LPCM and another coded as stereo
LPCM. Another disc might contain one selection coded
as stereo LPCM and another coded in an optional format
such as Dolby Digital; advantageously, Dolby Digital
tracks can be played in a DVD-Video player. Still
another disc may include a DVD-Audio selection of up
to six channels at 24/96 (possibly compressed with
MLP), a stereo LPCM selection, and a Dolby Digital 5.1
channel selection on the DVD-Video portion.

DVD-Audio can employ the SMART (System
Managed Audio Resource Technique) feature with
LPCM tracks. Using SMART, a player can mix down a
multichannel audio program to two channels for play-
back over a stereo system. The content provider
controls the down-mixing by selecting one of sixteen
coefficient tables. Each coefficient table defines level (0
to 60 dB), pan position, and phase; different tables can
be used for each track in an Audio Title Set. With
SMART, a separate stereo mix is not necessary on a
multichannel disc, not wasting disc space. Use of
SMART is optional on discs, but its support is manda-
tory in players.

The DVD-Audio format uses optional content
protection employing encryption and embedded water-

mark technology. The Content Protection for

Pre-Recorded Media (CPPM) encryption code is

stronger than that used in the DVD-Video format and

has the capability to revoke, expire, or recover encryp-

tion keys. An optional CPPM watermark identifies

content through unencrypted digital (and analog) links.

It is not used in high-speed encrypted links and instead

verifies copy status of unencrypted signals. The water-

mark is contained in the audio signal and is robust over

analog and data-compressed transmission links.

Audio Contents

Combination Channel Combination

Playback Time per Disc Side

8cm Disc

Single Layer Dual Layer Single Layer Dual Layer

2 channel only 48k/24-bit/2 ch 258 min 469 min 80 min 146 min

2 channel only 192k/24-bit/2 ch 64 min 117 min 20 min 36 min

2 channel only 192k/24-bi/2 ch 125 min 227 min 39 min 70 min

Multichannel Only 96k/24-bit/6 ch 86 min 156 min 27 min 48 min

2 ch and multichannel 96k/24-bit/2 ch +96k/24-bit/3 ch and 48k/24-bit/2 ch 76 min each 135 min each 23 min each 41 min each

Figure 30-16. Examples of playing times in DVD-Audio discs, not using MLP coding.

Channel Number

012 3 45

Mono/stereo

playback

1C

2L R

Left front,

Right front

weighted

3LfRf S

4LfRfLs Rs

5LfRfLFE

6 Lf Rf LFE S

7LfRfLFELs Rs

8LfRf C

9LfRf C S

10 Lf Rf C Ls Rs

11 Lf Rf C LFE

12 Lf Rf C LFE S

13 Lf Rf C LFE Ls Rs

Front

weighted

14 Lf Rf C S

15 Lf Rf C Ls Rs

16 Lf Rf C LFE

17 Lf Rf C LFE S

18 Lf Rf C LFE Ls Rs

Corner

weighted

19 Lf Rf Ls Rs LFE

20 Lf Rf Ls Rs C

21 Lf Rf Ls Rs C LFE

Channel

Group 1

Channel

Group 2

Figure 30-17. Channel assignments using CG1 and CG2.