Recording companies, audio-equipment manufacturers and component suppliers are bracing for a major shift in the formats that address needs for copy protection and higher-quality sound with 5.1 multichannel sound tracks, higher data precision and higher sampling rates. Some formats will compete for market acceptance, driven by ease of use, quality, cost and content availability.

The home-theater market has driven digital audio-compression standards. They evolved naturally from the cinema, with Dolby Digital and more recently DTS gaining wide acceptance for consumer products.

Dolby Digital is being broadly adopted for broadcast applications with satellite digital and HDTV. MPEG-2 stereo continues to have broad acceptance in older satellite- and cable-delivery systems, while a new version of MPEG-2, supporting multichannel, will be used in Europe for DVD and digital TV content.

The different decoding formats force manufacturers to deliver systems that support Dolby Digital, MPEG and DTS compression. Fortunately, software-programmable DSPs can make components cost-effective. The die size and cost of these decoders, like many DSP solutions, are driven by system-RAM requirements. By using a common memory resource for each decoder function, the incremental cost of supporting multiple decoders is modest compared with a single decoder ASIC solution.

Audio-compression formats for video have been set, but battles loom for high-quality audio-only content, which will more directly compete with CDs. While many proposals have been made, two major formats are emerging. Both add new copy-protection features and dramatically increase audio quality.

The DVD Working Group Four recently ratified an audio-only standard called Meridian Lossless Packing. Several companies expect to add this functionality to DVD video players as well as audio-only players.

Potentially competing with existing DVD-audio is Super Audio CD, a more-radical single-bit encoding format that plans a two-layer implementation, with the top layer remaining compatible with today's CD technology.

Products supporting DVD-audio and Super Audio CD will reach customers in 1999. These formats will deliver the pristine audio of multithousand-dollar home-theater systems to low-cost, mass-market products. But consumers, manufacturers, component suppliers and recording companies will all be affected by the potential confusion and final outcome of these new audio-standards battles.

The other format, the MPEG-2 Layer 3 and Advanced Audio Codec compression standard, is already being adopted for audio streaming on the Internet. Players can store about an hour of music on 64 Mbytes of flash, eliminating traditional magnetic or optical recording media, while providing CD-level sound quality.

As with all of the new audio formats, copy protection is a primary concern. In addition to supporting new audio-decoding standards, multimedia audio products are adopting more value-added post-decoding algorithms to further improve sound quality and reduce system cost. New products will provide sufficient Mips on a single core to eliminate additional processing engines. Next-generation solutions with up to 150 Mips will increase available post-decoder processing bandwidth to support a new class of 3-D virtualization, bass enhancement and speaker-equalization functions.

— Paul Bundschuh is digital audio applications manager for Motorola Inc.'S Consumer Systems Group.