Re: No more Dylan SACDs?

don freeman <dfreem3@xxxxxxxxxxxxxx> wrote:

> Thanks, Francois, for straightening me out about this very confusing
> technology. Let me see if I've got it right now.
>
> DVD-A refers to DVD-Audio, which requires a special DVD-Audio player.

Actually DVD-A albums generally feature the same tracks in two or more
formats (some of them can be read on a regular DVD player) and it's
specified on a label on the back cover.

For instance, here's the one for "Little Criminals" by Randy Newman:

Playback on DVD-Audio players
- Advanced Resolution Multi-Channel Surround Sound (96 KHz/24-bit)
- Advanced Resolution Stereo (192 KHz/24-bit)

Playback on DVD-Video players
- Dolby Digital 5.1 Surround Sound
- DTS 5.1 Surround Sound
- L-PCM Stereo

A video can be viewed from both systems.

Advanced Resolution Stereo and L-PCM Stereo are the original mix.

The L-PCM stereo version must be 48 KHz/16-bit (maybe 24-bit) making it
sound close to what a CD allows with some better definition in the
middle and high range. Frequencies determine bandwidth, the bit number
the accuracy. CDs are in theory limited to a bandwidth of 20 KHz as it
was decided: they're encoded at 44.1 KHz. The number must be divided by
two to express bandwidth, then 10 % or so were substracted for security.

But, in the real world, high frequencies on CD are filtered as low as 12
or 13 KHz on most of the CD players to prevent music from sounding too
synthetic or metallic. That's why vinyls still sound better than CD in
some areas.
Then, having your music mastered on a DVD gives you a little more room
on the high range, so your DVD should reproduce frequencies up to 16 or
17 KHz.
Of course, the Advanced Resolution stereo gives your far more bandwidth
and accuracy and it's for DVD-A players only.

But these discs are sold (or, should I say, were sold) mostly to people
who dig surround music, so a new 5.1 mix was created. Regular DVD
players can't have surround without digital compression (ie loss of
musical information). Dolby Digital is very compressed, DTS is much less
(and more efficiently) compressed to the extent it's said to be nearly
lossless.

Dolby Digital is here for the people who have an home cinema amp without
DTS decoders or for people with only a TV set or a stereo system that
believe that Dolby is better than uncompressed PCM because the Dolby
name sounds cooler.
DTS sounds better anyway than Dolby Digital.
And, of course, the "Advanced Resolution Multi-Channel" mode for DVD-A
will sound much better than DTS.

In other situations, you don't have enough room to put all you want on
the disc, so you have a two-sided disc, as it's the case for the "Pet
Sounds" DVD.
One side can only be read by a DVD-A player and it features the original
album in surround (new and conservative mix: some loudspeakers from a
surround system are never used by it), stereo (1996 mix) and mono
(original mix), all advanced resolution.
The other side can be played by any player, it promises a Dolby Digital,
DTS, and "Advanced Resolution" mono and stereo. As a matter of fact
(I've just checked) these mono and stereo tracks are as advanced as the
ones on the other side, so the DVD-A side mostly allows people to hear
the surround mix in its uncompressed glory.

It's quite confusing, which may help you to understand why these formats
have never really taken off (besides the fact you must wait for a minute
and navigate on a TV screen to understand what track you're playing).
But il helps selling aspirin.




>
> DualDiscs are cds that have a DVD on the other side of them. These
> either come in regular DVD sound, better DVD sound, or in DVD-Audio, so
> you can carry the disc over to your DVD-Audio player. But are these
> DualDiscs really two discs glued together, or just a single disc, burned
> on both sides?

You can't really burn a "disc" on two sides. Remember that a regular CD
consists of an extremely thin metallic layer (generally aluminum) where
the informations are inscribed. It is caught between layers of plastic
resin to protect it.

One-sided DVDs are the same, except that you can have a double
(metallic) layer with a precise alignment to allow a player to read both
when requested from one side and stock more data on this side. That's
what's called "DVD-9" on your DVD package: double layer means up to 9 GB
of data (DVD-5 is one side, one layer and 5 GB)

When you make a DualDisc, you won't lose your time and your money trying
to inscribe data on the two sides of the metal layer. It's far cheaper
and more reliable to snap two metal layers between layers of resin, and
one metal layer will be read from one side (CD) and the other layer from
the other side (DVD).

That's like a double-sided DVD. They are basically two DVD-5, one on
each side, and it was logically called DVD-10. Actually, I don't think
it really matters to know if at some point in the factory the two sides
were separated or always united. The important thing is to realize
there's nothing in a DVD-10 or a DualDisc that couldn't be also produced
in a factory as two regular DVDs or a CD plus a DVD.

Anyway people seems to prefer not to turn a disc and have a label on one
side (which protects it from scratches) and the more expensive to
produce dual layer discs (DVD-9) have been more of a hit. Hybrid SACDs
like the Dylan reissues were also dual layer discs, one layer could only
be played with a SACD player while the other layer could be played from
the same side as a CD.

Factory costs for DualDiscs come cheaper than the SACD costs, which is
part of the explanation for the recent Sony Music switch. The problem is
that due to the fact that the resin layer must be as thick on each side
of a dual-sided disc (while on a CD or a one-sided DVD, the resin near
the label was much thinner), DualDiscs are a little bulkier than a
regular CD. DVD players are used with such discs but some CD players
will have trouble with the extra bulk.

--
François Kahn
.

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