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.
|
