June 16, 2003
SACD & DVD-Audio: Ultra-High-Resolution Music
Since the invention of recorded sound over a hundred years ago, many different consumer audio formats have come and gone — 78 RPM records, LPs, 8-tracks, etc. We're now living in the age of the audio CD, but technological advances in digital recording and playback as well as the emergence of multichannel audio have led to the development of two new digital music formats: SACD and DVD-Audio.
Both SACD and DVD-Audio offer higher resolution sound than standard CDs, and in many cases, provide multichannel surround sound music, as well. Though these new format discs look exactly like standard CDs (and DVDs), they require a special player to unleash the ultra-high-resolution performance. Plus, to enjoy multichannel music, you will need a receiver with 5.1-channel inputs and a home theater speaker setup.
Which new music format is superior? The argument still rages. This article does not attempt to weigh in on either side of the debate (both formats sound great), but rather to give an overview of these emerging high-resolution options.
The lowdown on Super Audio CDs
Sony and Philips, the companies that teamed up to create the original audio CD, have reunited to develop Super Audio CD technology. SACD uses a new process of sound recording and reproduction called Direct Stream Digital™ (DSD). DSD enables a much more direct signal path than the Pulse Code Modulation (PCM) format of original CD, which requires a number of interpolation and over-sampling filters during recording and playback. The result of DSD's simplified signal path, and of its ultra-high 2.82 MHz sampling rate, is a more faithful reproduction of the original source material and richer, warmer sound.
Although SACDs look the same as standard discs, they can hold much more digital information than regular CDs. All SACDs contain a studio-mixed, high-resolution stereo signal, and many also contain a high-resolution surround sound signal, which can carry up to six independent channels.
Many (but not all) SACD recordings are hybrid discs. They contain two distinct layers of musical information — a Super Audio layer and a standard PCM CD layer. These hybrid discs deliver high-resolution sound when played on SACD players, and they're backwards compatible for standard digital sound with regular CD players.
The lowdown on DVD-Audio discs
DVD-Audio uses completely different technology to achieve its ultra-high-resolution performance. Instead of abandoning the PCM audio technology, they've improved it. DVD-Audio discs take advantage of higher sampling rates — up to 192 kHz, compared to 44.1 kHz for standard CDs. Plus, DVD-Audio discs use the Meridian Lossless Packing (MLP) system that allows discs to hold up to seven times as much information as standard PCM CDs. The result is richer, more detailed sound.
Nearly all DVD-Audio discs are engineered for surround sound with up to six discrete channels of high-definition audio, though there are some ultra-high-resolution 2-channel recordings, too. Most DVD-Audio discs also contain a compressed Dolby® Digital version of the music for backwards compatibility with standard DVD players.
To experience everything DVD-Audio discs have to offer, it's best to use them with your television. (Since all DVD-Audio players also play DVD-Video discs, your component will probably be hooked up to your TV anyway.) DVD-Audio discs typically contain added video and graphics content. Though the onscreen features vary from disc to disc, you may be treated to brief video clips, interviews, lyrics, and slide shows. But don't expect extended concert footage or full-length videos for all the tracks — there's only so much room on the disc, and DVD-Audio is primarily a hi-fidelity audio format.
Looking to the future, compatible with the past
As stated above, you will need a special player to access the ultra-high-resolution performance of SACDs and DVD-Audio discs. Some in the industry predict a format war, where one system ends up the big winner, while the other disappears from the planet (remember VHS and Beta?). However, since both formats have now co-existed for a number of years, it appears more likely that both formats will continue to survive — there are currently quite a few universal players that handle both SACDs and DVD-Audio discs.
Fortunately, the many backwards-compatibility safeguards with both formats ensure that no matter what happens, the consumer will not be hung out to dry. All SACD and DVD-Audio players also play standard CDs and many play DVD-Video discs. Plus, the SACD and DVD-Audio discs themselves usually also carry a version of the album in CD format or Dolby Digital, so standard CD and DVD players can play them, too. As prices continue to drop with high-resolution players, there's virtually no risk involved in trying out one of these new formats.
