GOODSOUND!GoodSound! "Features" Archives

Published May 1, 2003

 

Choosing Between DVD-A, SACD, and CD

Format wars have been going on for quite a while now. Neanderthals waged the first fierce format war when proponents of igneous rocks lumbered out of their caves to battle it out with hair-covered fans of sedimentary rocks to see which chunks of stone were best suited for bangin' on foes and prey. Skip ahead a few years to the mighty battle between JVC's VHS and Sony's Betamax videotapes, in which the better format, Betamax (which provided higher-quality video), lost out to the superior marketing might of the maker of VHS.

The audio world has witnessed a few of these skirmishes, too. Some of the more memorable: 78s versus 45s (this took place in the 1940s), vinyl versus cassettes (1970s), and then cassettes and vinyl versus compact discs (1980s and '90s). The latest format war is between DVD-Audio (DVD-A) and the Super Audio Compact Disc (SACD), with the winner hoping to own the hearts and credit cards of audiophiles everywhere. We're going to look at the positives and negatives of each, as well as those of the venerable CD, in order to help you decide which format might best suit your needs. So before you toss your CD player in order to make room for a new DVD-A or SACD player, or one of the universal players that can handle both formats, please read on. We have a few surprises for you.

Setting the stage

No one gets more pleasure and profit out of watching format wars than record labels. When CDs defeated cassette tapes and vinyl in the late 1980s/early '90s and became the dominant format, label executives danced in glee. Execs knew that since Joe Citizen had been convinced of the superior technology of the little silver discs, he was going to run out and buy CD copies of his old vinyl album favorites, regardless of whether Joe's vinyl copy of Magical Mystery Tour was in pristine shape and sounded wonderful or not. Joe didn't want his next-door neighbor, Jane, bragging over the backyard fence about the "perfect sound" of her new CDs.

One of the things mostly ignored in the press in those giddy days was that some record labels just happened to be arms of the same corporations manufacturing audio hardware (prime example: Sony bought Columbia Records and its subsidiaries in 1988). These media conglomerates cleaned up when Jane and Joe bought their CD players and cleaned up again when the pair went out to replace their vinyl collections with compact discs (which just happened to be more expensive than the vinyl records had been).

To help you to decide on SACD, DVD-A, or even CD, we'll begin with descriptions of just how the new formats reproduce music. For the sake of space, we're going to make a few assumptions about CDs and you: that you know obvious things like what a CD is and what it's capable of, and less-obvious stuff, too, like how a CD stores digital information. We're going to go over some storage-technology similarities between DVDs and CDs below, but if you'd like more information, check out "How to Choose Between a CD Player and a DVD Player" originally published in October, 2002.

DVD-A: picture this

DVD-Audio is, quite simply, the audio version of the enormously popular DVD-Video. It employs the same technology -- with a focus on audio rather than video -- enabling listeners to enjoy multichannel sound as well as two-channel music if they're so inclined.

DVD-A is being pushed by folks at Warner Music (owned by AOL Time Warner), as well as hardware-makers such as Pioneer, Panasonic, Toshiba, and Meridian Audio (you'll notice this name again in a few seconds), among others.

DVD-A's high-density storage technology is an evolution of PCM (pulse code modulation), which is also the digital audio technology employed in CDs and CD players. PCM technology takes an analog signal (an electrical pulse varying in current or voltage, just as the sounds you hear are variations in air pressure) and feeds it into an analog-to-digital converter, which changes the analog signal into a digital code. The converter looks at (samples) the analog information at incredible rates: 44,100 times per second in ordinary CDs and up to 192,000 times per second in DVD-As. Each sample is then assigned a number; in the case of the typical CD, it's a series of 16 ones and zeroes. Each one or zero is known as a bit. The ordinary CD you buy is a slice of 16-bit/44.1kHz technology. DVD-A can have digital resolutions all the way up to 24-bit/192kHz for two-channel music and 24/96 for multichannel recordings. (Note: With DVD-A, not all channels have 24/96 resolution. This high resolution is typically reserved for the two most important channels going to the pair of main speakers, with the surrounds receiving lower-resolution 24/48, for example. This is done to save space on the disc, enabling more program material to be included.)

The higher the digital resolution, the better the sound you hear. Why is the sound better? Because there's more musical information presented to your ears by a DVD-A than a CD. Some sounds are more compressed on CDs, and can even be discarded when stored via this format. DVD-As feature a technology known as Meridian Lossless Packing (MLP), which is a more effective compression system that, as its name declares, loses no sound-information.

All of this means that there's more info for your ears and brain to process, so the listening experience presents a more accurate reproduction of the original performance of the music. (We'll soon get to whether or not this additional information is worth the price of a DVD-A player or one of the new DVD-A/SACD/CD hybrid players.)

This very same claim of delivering more precise and complete sound is also touted by the proponents of SACD, of course.

SACD: life is but a stream

Sony and Philips are the two behemoths pushing Super Audio Compact Disc and its Direct Stream Digital (DSD) technology -- the so-called "PCM killer." Sony and Philips have had some success in this format-war stuff because they teamed up to bring CDs to the world, or the world to CDs, however you care to look at it.

DSD is fundamentally different from PCM technology. The musical waveform sampled 44,100 times per second in a typical CD is sampled at a mind-wobbling 2.8 million times per second with SACD. Rather than breaking the binary code into bits of 16 or 24, SACD samples it as a continuous stream of information. Like DVD-A, SACD employs a lossless form of compression that squeezes an enormous amount of information onto a disc the size of a CD without discarding any information. (Some SACDs contain a layer of standard CD information, which can be read by a standard CD player's laser, as well as a layer comprised of the DSD information, which can only be accessed with the more precisely focused lasers available in SACD players.)

Also like DVD-A, SACD offers the expansion of the music-listening experience via multichannel music reproduction (six channels are available on SACDs). And again, like DVD-A, there's simply no doubt that the music recorded and mixed for SACD is of higher quality than you'll get from a typical CD on a typical CD player. There's simply more information -- a more complete digital picture of your music -- for you to hear and enjoy.

To be continued . . .

In our next installment of "Choosing Between DVD-A, SACD, and CD," we'll take a look at the pros and cons of each format. You'll find that both of the two new formats offer sometimes-compelling reasons to choose one over the other (or both, via a universal player, which will play SACDs, DVD-As, and CDs). There are also quite a few interesting points in favor of sticking with that ol' CD player you have that works just fine. So don't run to your favorite audio dealer just yet.

Stay tuned.


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