DVD Audio
DVD-Audio is a standard of sound recording designed to tap the full potential of DVD as a
pure music medium. While currently there is not a flood of
recordings in the format known as DVD-Audio (or DVD-A), the best examples take
the experience of listening at home to a new level of realism.
The achievement of DVD-Audio is extraordinary in two respects. First, the naturalism of DVD-A sound far exceeds the
inherent capacity of conventional CD. Where the CD can hold about 650 megabytes
of data, a DVD boosts that storage to 4.7 gigabytes. Add to that a digital
compression technique that results in zero loss of data in playback, and you
have a very fine print of the original sonic image.
But second and no less important, DVD-A is a multi-channel
format, which means it accomplishes convincingly the surround sound effects — the evocation of space and ambience — that the recording industry
and electronics manufacturers tried to capture 30 years ago with
quadraphonic sound from LP records.
Surround sound isn't merely a clever spin on
"stereo," but an expression of musical realism that recording
engineers have always aspired to.
It was the medium of the LP record, with its two groove walls
traced by a gliding stylus, that dictated the two channels of stereo as it first
appeared in the late 1950s.
While stereo LP vinyl records sounded better than previous formats and CD
eliminated the clicks and pops of a stylus riding over imperfections in the
record groove, DVD-A takes it up another notch. You might say a CD sounds
"really good" but with DVD-A surround sound, you will say
"WOW!".
DVD-A recordings can also include video
segments, still images, song titles, and even the words. DVD-Audio discs are
generally priced around $15 each. While only a DVD-Audio player (or universal
player) can read specific encoding, most DVD-A discs include a Dolby
Digital 5.1 track, playable on any DVD machine. Which means you can enjoy these
discs now, on your home theater system.
DVD Audio and DVD
Video are different formats.
DVD Audio discs: In
order to take advantage of higher-quality DVD audio discs, you
will need a DVD player with a 192kHz/24-bit digital-to-analog
converter (DAC). Many DVD players have only a
96kHz/24-bit digital-to-analog converter. So if you want to be
able to listen to DVD audio discs, be sure to look for a DVD
audio player with a 192kHz/24-bit digital-to-analog
converter.
DVD Audio recordings can provide far better sound quality
than CDs. The chart below lists the sampling rate and accuracy
for CD recordings and the maximum sampling rate and accuracy
for DVD recordings. CDs can hold 74 minutes of music. DVD
audio discs can hold 74 minutes of music at their highest
quality level, 192kHz/24-bit audio. By lowering either the
sampling rate or the accuracy, DVDs can be made to hold more
music. A DVD audio disc can store up to two hours of
6-channel, better than CD quality, 96kHz/24-bit music. Lower
the specifications further, and a DVD audio disc can hold
almost 7 hours of CD-quality audio.
| Specification |
CD Audio |
DVD Audio |
| Sampling Rate |
44.1 kHz |
192 kHz |
| Samples Per Second |
44,100 |
192,000 |
| Sampling Accuracy |
16-bit |
24-bit |
| Number of Possible Output
Levels |
65,536 |
16,777,216 |
In an audio CD or DVD, each bit represents a digital
command telling the DAC what voltage level to output. While an
ideal recording would follow the raw waveform exactly, digital
recordings sample the sound at different frequencies, and
therefore lose some of the data.
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.
You will need a
Universal DVD player or high-end DVD player/recorder to access the ultra-high-resolution performance of
SACDs and DVD-Audio discs. It appears that both formats will survive; there are already some
universal players that handle both SACDs and DVD-Audio discs.
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 formats.
DVD AUDIO - FAQ
| What is DVD Audio?
DVD Audio (or DVD-A) is a
music format that offers very
high quality audio, longer playing times and the possibility of additional
features not available on normal CDs.
DVD Audio uses a form of lossless
audio compression known as Meridian Lossless Packing (MLP). This means that none
of the audio information is discarded and allows for more data to be fitted onto
the DVD-A disc without loss of quality.
DVD Audio discs can therefore provide
Advanced Resolution Surround (multi-channel surround sound up to 6 channels) and
Advanced Resolution Stereo (2 channels) as well as the same track in Dolby 5.1.
Some discs may include DTS 5.1 and LPCM Stereo sound.
DVD-A discs can also
carry video and limited interactivity; this may include things like song lyrics,
video clips, artist commentaries and photo galleries.
DVD-Audio is a format specifically designed
to provide the highest possible audio fidelity capable on DVD. The audio
fidelity of DVD-Audio far exceeds the quality of conventional CD's and audio
on DVD-Video.
DVD-Audio takes advantage of the large
storage capacity, speed and flexibility possible with DVD. DVD-Audio provides
for audio in stereo and in multi-channel surround in a wide range of
specifications. In addition to audio, a DVD-Audio disk can contain a limited
amount of video, which can be used to display text, such as lyrics or notes;
or stills such as a photo album. Up to 16 graphic stills can be associated
with each track and on-screen displays can be used for lyrics and disc
navigation. As an option, a DVD-Audio disc can also include audio tracks
recorded in the DVD-Video specification (Dolby Digital and DTS) for
compatibility with DVD-Video players.
A DVD disc is capable of recording video,
audio and data information of many different types and formats. An industry
group, named the DVD Forum has responsibility for establishing the industry
standards and formats for DVD. In 1996, The DVD Forum released the DVD-Video
format, which was designed to deliver video at a quality exceeding VHS tape
with surround sound and better than CD audio. Before defining a DVD format
optimized for audio, the DVD Forum sought the opinions of the music industry
and audio equipment manufactures. In January 1998, the DVD Forum’s Working
Group 4 released a draft DVD-Audio standard. In July 1998, the DVD Forum
released the preliminary 0.9 version. In March 1999, the DVD Forum released
the final version 1.0 of the DVD-Audio specification.
What do I need?
A DVD PLAYER – DVD-Audio discs will offer you outstanding
Dolby Digital multi-channel surround sound on any DVD-Video player connected to
a multi-channel surround sound playback system. However, in order to enjoy the
full Advanced Resolution audio quality offered by DVD-Audio, a DVD-Audio player
is required. In order to view the disc menu options and interactive features
offered on the DVD-Audio disc, you will need to use your TV.
You can enjoy
recorded music without the use of your TV, as the disc is designed to play just
like a CD.
What different types of DVD Audio disc are available?
There are four different kinds of DVD-A discs.
| |
CAPACITY (GB) |
LAYERS |
SIDES |
| DVD-5 |
4.7 |
1 |
1 |
| DVD-9 |
8.54 |
2 |
1 |
| DVD-10 |
9.4 |
1 |
2 |
| DVD-18 |
17.08 |
2 |
2 |
|
What is the difference between DVD Audio and CD?
DVD-A discs can hold up to seven times more data capacity than CDs. This extra space is used to fit higher quality audio. The sampling rate of
a DVD-A can be up to 192kHz, compared to 44.1kHz for CD, and the digital sound
can contain up to 24 bits of data (16 bits on CD). DVD Audio discs can also
offer multi-channel surround sound, which CDs cannot.
What is the difference between DVD Audio and DVD Video?
DVD Video is primarily a visual medium. The available space
on the discs is reserved mostly for video data, leaving less room for sound.
Because of this, DVD Video offers compressed stereo and multi-channel surround
sound.
DVD Audio is primarily an audio medium, where the majority of the disc
space is used to fit far superior sound. Therefore DVD-A discs can offer
Advanced Resolution Stereo and Multi-channel Surround, without requiring the
compression methods used on DVD Video to save space.
Can I play DVD Audio discs on a DVD Video player?
The vast majority of modern DVD Video players are Universal
players, which means that they support the DVD Audio format. Also, most DVD-A
discs contain a Dolby 5.1 surround sound track, allowing them to be played on an
ordinary DVD Video player. However, you may need a higher-end universal player in
order to enjoy the full capabilities of some DVD-A discs as they could be
encoded with a sampling rate which is higher than some DVD Video players can
handle.
Can I play CDs on a DVD Audio player?
Yes, CDs will play on a DVD Audio player as they do on most
DVD Video players.
What special features are available on DVD Audio?
DVD Audio discs can contain a lot more than just the audio
track. They may include video clip, photos, text (such as song lyrics or artists
bibliographies), DVD-Rom data and interactive menus.
What is the DVD-Audio Specification?
DVD-Audio allows for a wide variety of audio formats at varying levels of
specification. DVD-Audio supports the same multi-channel audio formats used with
DVD-Video. Therefore both DVD-Video and DVD-Audio can provide high definition
multi-channel audio recorded in the Dolby Digital and DTS audio formats.
However, the real advantage of the DVD-Audio specification over DVD-Video and CD is
in the significantly increased quality of the PCM audio format. PCM or
"Pulse-Coded-Modulation" is the audio format standard for CD’s and
available on many DVD-Video’s.
DVD-Audio supports a significantly higher quality of PCM audio than is
possible on CD or DVD-Video. Full multi-channel surround sound can be recorded
in high fidelity PCM creating a sound field with the ambience and fullness of a
live performance. DVD-Audio PCM can be recorded with a range of frequencies that
are more than four times that of a CD; giving instruments a liveliness and
expression that is not possible on a CD. DVD-Audio PCM also has a much greater
dynamic range that possible on a CD - making louds louder and quiets quieter.
The greater storage capacity of DVD’s allows for much more music to be
recorded than possible on CD's.
The DVD-Audio specification requires PCM audio while the Dolby Digital, DTS
and MPEG audio formats are optional.
For compatibility with DVD-Video players,
DVD-Audio discs can include audio encoded in Dolby Digital and DTS formats
that satisfy the DVD-Video specification.
However, DVD-Audio players automatically default to the highest level of DVD
specification. Therefore, a DVD-Audio player will only recognize the PCM
DVD-Audio tracks on a DVD-Audio disc and will NOT recognize Dolby Digital or
DTS audio tracks recorded at the DVD-Video specification. Although these Dolby
Digital and DTS tracks are playable on a DVD-Video player, they are invisible
to a DVD-Audio player. This applies even if the player supports the DVD-Video
specification.
The following table outlines the technical specifications for PCM on
DVD-Audio and standard CD’s.
|
Specification
|
DVD-Audio
|
CD
|
|
Audio Format
|
PCM
|
PCM
|
|
Disk Capacity
|
4.7Gb - Single layer
8.5Gb - Dual Layer
17Gb – Double Sided Dual Layer
|
650Mb
|
|
Channels
|
Up to 6
|
2 (stereo)
|
|
Frequency Response
|
0 - 96kHz (max)
|
5 - 20kHz
|
|
Dynamic Range
|
144db
|
96db
|
|
Sampling Rate - 2 channel
|
44.1, 88.2, 176.4KHz or
48, 96, 192KHz
|
44.1kHz
|
|
Sampling Rate - multichannel
|
44.1, 88.2KHz or
48, 96KHz
|
n/a
|
|
Sample Size (Quantization)
|
12, 16, 20, or 24 bits
|
16 bits
|
|
Maximum Data Rate
|
9.6 Mbps.
|
1.4Mbps
|
With PCM, the ability to accurately represent an analog signal in digital
form is mainly dependent upon the "Sample Size" and "Sampling
Rate". The combination of Sample Size and Rate are commonly represented as
two numbers such as 24/96 meaning a 24-bit sample size taken at a rate of 96,000
samples per second.
Sample Size or "Quantization" is the number of data bits used
to represent the analog audio signal each time it is sampled when being
converted from an analog signal to a digital form. A larger number of bits allow
the amplitude of the audio signal to be represented more accurately.
Sampling Rate or Sampling Frequency is the number of samples taken per
second when converting the analog signal to digital. A higher "sampling
rate" allows for higher frequencies to represented.
Data Rate is the number of bits-per-second that can be processed. A data
rate of 9.6Mbps is 9.6 million bits-per-second.
The greater the number of bits used for Sample Size and the greater the
number of Samples per second (Sample Rate) the more accurately the analog signal
can be represented in digital form. With a Sample Size of 24 bits and a Sample
Rate of 192KHz (24/192), DVD-Audio is capable of recording an audio signal with
a frequency range of 0 to 96KHz with a dynamic range of 144dB.
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