But in a move that took industry watchers by surprise, Sony also announced that it intends to implement DVD-Audio in its DVD products. SACD and DVD-Audio have been competing for dominance as the next-generation audio format ever since Sony and Philips proposed SACD in November 1997.

Meanwhile, hardware vendors are preparing players that are compatible with both SACD and DVD-Audio.

"SACD is for pure audio and has nothing to do with a format dispute," said Nobuyuki Idei, president of Sony.

The Super Audio CD employs Direct Stream Digital (DSD) as the fundamental recording technology. DSD uses a sampling rate of 2.8224 MHz to record a 1-bit signal directly, thereby eliminating the need for decimation filtering in the recording process and interpolation filtering in the playback process. Thus, according to Sony, the resultant digital signal very closely resembles the shape of the original analog waveform. Sony claims to have achieved a theoretical playback frequency range of up to 100 kHz and a dynamic range in excess of 120 dB across the audible range.

Built-in protection

To guard against unauthorized copying, SACD employs both invisible and visible watermarking on the disk, and content is encrypted before recording. The SACD players will have no digital output for the SACD signal.

Sony is positioning the player at the ultra-high end of the consumer-audio market. The player will debut in Japan at $4,170. Overseas shipments are expected to begin by the fall.

When the Sony/Philips group first proposed SACD, compatibility with existing CD players was considered as critical to the design as high-quality sound output. A brochure on technical proposals distributed by Sony in November 1997 stated that Super Audio would maintain "compatibility with existing CD players while taking advantage of an entirely new approach to audio recording and reproduction." The envisioned disk was to have two layers: a high-definition (HD) layer for the SACD signal and a CD-signal layer.

The subsequent spec supported three options: a single-layer HD disk, a dual-layer HD disk and a hybrid disk with one CD layer and one HD layer. But Shigeo Maruyama, president of Sony Music Entertainment (Japan) Inc., said he proposed that the hybrid option be dropped so that the spec would "just focus on high-quality sound."

"We are considering offering hybrid disks with the condition that their cost would not differ [from that of single-layer disks], but in reality, the cost becomes very high," Idei said.

Sony Music Entertainment (SME) will release 13 SACD software titles in coordination with the hardware launch. They are all HD single-layer disks with a two-channel SACD signal. SME said it plans to add software at a rate of 10 titles per month. Multichannel capability for SACD remains under development.

SME, a Sony subsidiary, admitted that it would be costly to carry SACD disks in addition to other formats, Maruyama said. Sony said that multiple record vendors support the SACD format, but since only 500 units a month will be produced, software suppliers will be limited to SME at the beginning.

Sony also acknowledged that it will implement DVD-Audio in Sony's DVD products. "In terms of technology, developing hardware that plays both formats is possible," said a spokesman for Victor Company of Japan Ltd. (JVC), which chaired the DVD-Audio format effort.

Whether or not such hardware will appear will depend on users' and software producers' demand, the JVC spokesman said. Some analysts say that several audio manufacturers already have been developing such hybrid players.

Sony, for its part, said it does not intend to confine SACD to super-high-end audio. "As the cost of SACD [decoding] circuitry is negligible once it is designed into a CD chip, we are going to implement SACD capability in all CD players, including low-end portables," said Yoshinori Yamamoto, senior vice president of Sony's Home A&V Products Co.

Supporters of DVD-Audio, including Matsushita, JVC and Pioneer, said they plan to field products starting this summer.