Although much of this section contains fundamental information on basic audio technology, extensive information on new evolving digital audio formats and recording and reproduction systems has been added since the last edition.

As noted herein, DVD-Audio, for example, is based on the same DVD technology as DVD-Video discs and DVD-ROM computer discs. It has a theoretical sampling rate of 192 kHz with 24-bit processing and can store 4.7 gigabytes on a disc with a choice of two- or six-channel audio tracks or a mix of both. Super Audio CD (SACD) has the same storage capacity. It uses direct stream digital (DSD) with 2.8 MHz sampling in three possible disc types. The first two contain only DSD data (4.7 gigabytes of data on a single-layer disc and slightly less than 9 gigabytes on the dual layer disc). The third version, the SACD hybrid, combines a single 4.7 gigabyte layer with a conventional CD that can be played back on conventional CD players.

MPEG audio coding variations continue to evolve. For example:

• MPEG-1 is a low-bit-rate audio format.

• MPEG-2 extends MPEG-1 toward the audio needs of digital video broadcasting.

• MPEG-2 Advanced Audio Coding (AAC) is an enhanced multichannel coding system.

• MP3 is the popular name for MPEG-1 Layer III.

• MPEG-4 adds object-based representation, content-based interactivity, and scalability.

• MPEG-7 defines a universal...