DVD Audio and SuperAudio CD Formats
presented by Jim Heckroth, Crystal Semiconductor
JPG photos of this meeting
Written by Gary Louie, AES PNW Secretary
October 20, 1999 at Jack Straw Studios
PNW Chair Aurika Hays opened the October meeting at Jack Straw Productions
studios in Seattle. All of the approximately 34 in attendance briefly
introduced themselves. She then introduced Jim Heckroth, Marketing Manager
for audio and automotive DSP products for Crystal Semiconductor, which deals
with both DVD Audio and SuperAudio CD components.
He began with some history. In December 1995, a DVD Audio working group was
formed, (after DVD Video was already established), to explore high quality
audio on a DVD disc. Record companies and allied organizations also formed
the International Steering Committee (ISC) to help decide DVD audio
standards. Sony/Philips developed a competing format, the SuperAudio CD. A
format war now needs to be decided in the marketplace.
On the DVD Audio side, there were basic requirements: it would be based on
DVD video disc physicals, have multichannel audio superior to current CD,
copyright/antipiracy controls, backward compatibility, allow limited
video/text display capabilities and conditional access, and have menus and
packaging (layers/sides) like DVD video. A 74 minute capacity like CD was
The format allows increased sampling rates/sample size for better fidelity.
It is based on linear PCM up to 24 bit 192 kHz sampling. Two audio formats
are noted: DVD Audio only and DVD A-V (with limited video capabilities).
Consumers will need new players for the new audio discs.
DVD audio data can be compressed with Meridian Lossless Packing (MLP)- no
bits are lost, not unlike compacting computer files, but decoded here in
real time. There are 21 data format combinations possible, using 16/20/24
bits and multiples of 44.1 and 48 kHz sampling rates, juggled up to a
maximum data rate. DVD Audio capacity at a normal CD stereo 16/44.1 rate
(compressed, single layer) would be 516 minutes versus a normal CD's
approximately 74 minutes. There is no region coding. A method exists for
in-player mixdown from multichannel to stereo with mixdown vectors. You
could also put 2 mix versions on the disc, but you would use more space on
the disc. The digital watermarking scheme puts a low data rate stream into
the audio stream, and may affect the audio.
At intermission, a drawing was held for prizes, two T-shirts provided by
Jim than continued with information on the Sony/Philips SuperAudio CD
(SACD). It was an offshoot of a Sony project to archive digital masters with
a very high quality method. Delta-Sigma converters use a 1 bit modulator at
a very high sampling rate instead of linear PCM, which they call Direct
Stream Digital. The disc is dual layer with one layer ordinary red book CD
audio and the other layer DSD, and the actual disc construction is similar
to the DVD video disc.
SuperAudio CD can watermark by creating a visible pattern on the disc by
modulating the pit sizes, as well as putting watermark and copy coding in
the data stream. The watermarking is claimed to not affect audio at all.
SACD also has a lossless data compression scheme.
The group discussed the 2 systems at length. Both systems have about the
same fidelity, on paper. There was some discussion of the audibility of
higher sampling rates, antialiasing filters, etc.
Jim noted that Crystal likes the 1 bit modulator with switched capacitor
filters because they are nicely linear, however, they can have some jitter
problems. Multi-bit converters have less jitter sensitivity, but also less
linearity (more THD).
No one knows if the SACD backward compatibility feature will work reliably,
or if it is important to consumers. Initial players will be aimed at early
adopter audiophiles and will be expensive - maybe $5K.
The question was posed: Why not always use MLP in DVD Audio if it works as
advertised? The answer is not clear. Some noted that studios will need
mastering tools. Jim said that Crystal is only making decoders now, and no
Marketing will likely determine the format winner.
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