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Published Articles - (Issue 43 of Widescreen Review)

	Back To Articles Main Page DVD-Audio - Boon Or Boondoggle? By Richard Hardesty New Incompatible Recording Formats The DVD-Audio disc and the Sony/Philips Super Audio CD (SACD) use new, incompatible recording formats. They are designed to deliver high-quality music to our homes in the new millennium. Each is touted as the twenty-first century replacement for the venerable compact disc. Both utilize 5-inch optical discs as a recording medium, but the way in which information is stored on these discs is quite different. (I wrote a reasonably comprehensive article covering the two new formats in Issue 29 of Widescreen Review, entitled "Hi-Fi '98 Show News.") Super Audio Compact Disc (SACD) The Super Audio Compact Disc (SACD) uses the Sony/Philips Direct Stream Digital (DSD) recording process, which is a 1-bit system with an extremely high sample rate (2.8MHz). DSD is closer to analog than other digital recording processes. DSD requires no conventional digital-to-analog conversion and eliminates the need for decimation filtering, which is used to make linear pulse code modulation (LPCM) recordings. SACD discs offer frequency response to nearly 100kHz, providing much broader bandwidth and more linear phase characteristics than what CD can offer, and SACD has far greater dynamic range than conventional CD, allowing the subtleties of music to be more naturally reproduced. Super Audio Compact Discs using DSD recording technology have been very favorably received by members of the high-end audio community including yours truly. See my articles on the Web at: www.widescreenreview.com/todaynews/audperf04.html and www.widescreenreview.com/todaynews/audperf07.html SACD was introduced as a two-channel system and all currently available discs are stereo only. Virtually all of the audiophile recording companies have embraced the format. The SACD can support multichannel recordings which may or may not become available in the future, based on consumer demand. Initially, SACD has been positioned by Sony and Marantz (a Philips company) as a high-end audiophile format to deliver high-quality stereo recordings with audio content only. Philips, however, showed a six-channel SACD player at CEDIA (Custom Electronic Design & Installation Association) EXPO in September and announced to the press that they plan to introduce it to the public later this year. Dual-layer SACD discs can provide backward compatibility with conventional CD players by incorporating a second layer that conforms to the "Red Book" CD standard, allowing the disc to play in any current CD or DVD player. Unfortunately, most of the currently available SACD discs are not dual-layer and, therefore, are not compatible with other optical disc players. DVD-Audio DVD-Audio discs use the linear pulse code modulation (LPCM) digital recording method, much like the current LPCM system used on conventional CDs but with optionally higher sample rates (up to 192kHz) and optionally greater dynamic range due to increased bit depth (up to 24-bit samples). For comparison, conventional CDs have a sample rate of 44.1kHz and a sample size of 16-bits, and the LPCM tracks on most DVD-Video discs are similar, with a slightly higher sample rate of 48kHz. (The DVD-Video disc standards allow for 96kHz/24-bit audio, but discs made with this level of audio resolution will have very limited video capacity.) DVD-Audio discs can start at these lower resolutions and go up from there if space permits. The more stuff that is included on the disc, the less space there will be for increased resolution on the audio tracks, however. The DVD-Audio standards can support a variety of two-channel and multichannel recording options with or without "lossless" compression, utilizing the Meridian Lossless Packing (MLP) system. Digital sample rates and sample sizes can be varied at the discretion of the content producer to either extend playing time, add additional audio channels or video content or to improve audio quality. Providing many channels of audio information or adding video content will require compression or reduction of audio resolution or both. (As an example, 96kHz/24-bit audio requires 2.3 megabits per second, per channel. Six channels would require 13.8Mbps, which is greater than the allowable maximum DVD-Audio data rate of 9.6Mbps.) DVD-Audio can also support very high-quality, uncompressed stereo recordings with up to 192kHz/24-bit resolution, but utilizing that high sample rate will leave little room for additional features like images or multichannel sound. Still pictures and a limited amount of full-motion video can be included on the discs if desired, but the limits of storage space (4.7GB for single-layer discs) and data transfer rate (9.6Mbps) require a quality-versus-quantity trade-off. DVD-Audio discs are meant to coexist with DVD-Video discs, not supplant the latter, which are still today's highest quality source for full-length movies and full-motion music videos. The DVD-Audio disc has been positioned as the higher-resolution source for surround sound music. The DVD-Audio format has been promoted as a medium that provides all things audio and some things video to all people, but there are some questions about whether that is true and there have been problems that have delayed the launch of this new format. DVD-Audio has been "just around the corner" for about two years now. (Working Group 4 of the DVD Forum chose MLP as the standard compression format for DVD-Audio in December 1998.) Manufacturers have used copy protection issues as the excuse for the delay in bringing the new format to market, and there is still debate about the sonic consequences of watermarking and encryption. The SACD format, on the other hand, has been embraced by high-end recording companies and audiophiles, and a good selection of recordings from a number of different companies are available for sale now. While the DVD-Audio format has been marketed aggressively, it has never been demonstrated to the public before the CEDIA EXPO in September of this year, even by the inventors of the MLP lossless compression scheme, Meridian. This has caused many people to speculate about whether the system is completely perfected and whether it can actually deliver the sound quality that the specifications suggest. DVD-Audio Arrives? The first DVD-Audio players are on the market now, but there is no software available at all as I write this in mid-September. The two manufacturers who sent products for review (Pioneer and Technics) each provided a single demo disc to demonstrate the DVD-Audio format. The Pioneer player wouldn't play the Panasonic/Technics demo disc. The Technics player played both discs, but added its own sonic signature to the sound, making evaluation of the format difficult. These are the very first players to reach the market and these sample discs are obviously experimental. Evaluating the sonic potential of the new format under these conditions has been challenging, to say the least. In my reviews of the Pioneer and Technics DVD-Audio players, I have tried to relate my impressions of the sound of the players and the sound of the DVD-Audio format. These reviews are a preliminary evaluation made under hurried conditions with insufficient data about the recordings, but I've done the best that I could under the circumstances. The opinions expressed about sound quality are mine alone and may be useful as a listening guide, but you should listen for yourselves and make up your own minds about the validity of this new format and the quality of these new players. Here is some personal speculation about the long-term viability of the DVD-Audio format that contains important information that you should consider before rushing to the store to buy yet another DVD player. Do We Really Need Yet Another Format? Audiophiles can choose the SACD format, which provides the best possible fidelity for stereo music recordings and which is capable of providing surround sound content in the future. High resolution 96kHz/24-bit LPCM stereo recordings are also available now on DVD-Video standard discs. Videophiles and surround sound enthusiasts have the standard DVD-Video disc, which can provide discrete digital surround sound audio, encoded in Dolby® Digital or DTS® Digital Surround™, along with full-motion video content. Will an additional format that requires the purchase of a new DVD player and probably a new digital controller or receiver really provide any benefit to most people? Neither SACDs nor DVD-Audio discs will play in the disc player that you probably own now. (Technically, dual-layer SACDs are backward compatible but offer little sonic advantage from the CD layer and cost more. DVD-Audio discs can be made compatible with DVD-Video players by incorporating a Dolby Digital or DTS Digital Surround track in addition to the DVD-Audio track, but then all you've got is a DVD-Video disc with compromised video.) The new DVD-Audio players probably won't work with the digital controller or receiver you own now because very few models in the installed base of digital controllers and receivers have six-channel analog inputs. Are you ready to scrap the DVD player and digital controller you already own for a new format? SACD is a two channel medium, so SACD players can be used with any preamplifier or digital controller with stereo analog inputs, but you'll lose fidelity if your digital controller doesn't have analog pass-through capability because the DSD signal will be converted to PCM digital at low resolution (read my digital controller series in WSR for more information). DVD-Audio players, on the other hand, have six analog outputs, so multichannel DVD-Audio recordings can't be played back through most of today's digital controllers, preamplifiers or receivers which don't have six-channel analog inputs. SACD offers a huge demonstrable sonic benefit, however. Higher-Quality Stereo Audio SACD is the biggest single advance in audio quality that I've heard in the last forty years or so. DVD-Audio, on the other hand, has yet to demonstrate sound quality that is the equal of, let alone better than, the quality available from conventional CDs. (Meridian's first public demonstration of DVD-Audio at CEDIA Expo 2000 in September was consistent with my experience with the review samples. A cut they played from a decades-old Pink Floyd CD sounded much better.) If maximum sound quality is your major objective, SACD offers that in spades. A limited selection of DVD-Video discs with stereo audio material recorded at 96kHz/24-bit resolution are also available and they play on the DVD player you already have, but many players will downsample to 48kHz and many digital controllers can't accept a 96kHz signal. If you have a DVD player that outputs true 96kHz signals and a digital controller that can accept these signals, these discs offer a high-quality alternative for stereo music. The 96kHz/24-bit LPCM material on DVD-Video discs that I've heard sounds better than conventional CDs, but comes in a distant second-best compared to SACD in my opinion. The selection of recordings is extremely limited and the probability for a wider availability in the future is not good. Virtually all the audiophile recording labels, even those who originally supported 96kHz/24-bit LPCM, have switched to SACD. Surround Sound Audio If surround sound music is your primary objective, the need for a new format is really questionable. Surround sound music recordings are available now from DTS-encoded CDs and DVD-Video discs encoded in Dolby Digital or DTS Digital Surround. DVD-Video discs have full motion video so you can enjoy watching the performance as well as listening to it, and DTS-encoded CDs and DVDs provide excellent sound that is good enough for all but the most critical listeners, like me, who will probably choose stereo over surround sound for music anyway. All of these discs will play on the DVD player you already have and through the digital decoder you own now, which probably will not support the new DVD-Audio players which have six-channel analog outputs only. The Politics Of The Matter Sony and Philips developed the original compact disc technology and have been collecting royalties and license fees on CD discs and players for the past two decades. They want to continue this process by offering a new, improved version of the CD&emdash;the SACD. Other manufacturers are opposed to the continued domination of the music market by Sony/Philips and want a piece of the action for themselves. Matsushita (a maker of DVD transport mechanisms and an arch rival who will oppose anything Sony develops) and Dolby (who licenses MLP) are major forces in the industry. They may be able to convince manufacturers, content providers and the public of the need for yet another format that obsoletes their current DVD players and digital controllers, but they have yet to convince me. I'll have to hear something that sounds good enough to offer a genuine benefit to consumers that offsets the expense of a major system revision, and that hasn't happened yet. After reviewing the first SACD players from Sony and Pioneer, and the first DVD-Audio players from Pioneer and Technics, my vote goes to SACD for the highest possible fidelity for stereo music recordings, and to DTS-encoded DVD-Video discs and CDs for the best surround sound. This is a preliminary opinion based on auditions of just three new players and a very limited number of software selections, and you may disagree. If you decide that DVD-Audio really offers something better, be prepared to write some big checks to replace the components you're using now. Back To Articles Main Page