SACD layer

I'm a little confused as to how these work. I picked up DSOTM and wondered if the high-resolution stereo and a 5.1 surround version are on one layer. Is the stereo version just a down-sample of the surround, or are they separate altogether?


Amazon Album Description
The Super Audio CD (SACD) features two disc layers. One layer contains a standard version of the album that works on any CD player. The other layer includes high-resolution stereo and a 5.1 surround version of the recording that works on SACD-compatible DVD players and home theater systems. Both layers employ SACD's Direct Stream Digital (DSD) encoding process that samples the music 64 times faster than CD for unprecedented fidelity.

 

SACD tracks are all on one layer of a disc. The stereo and surround tracks are in separate sections of a single layer.

The cd layer is a separate layer. Amazon's listing seems to indicate that the cd layer of this particular disc was derived from the DSD master. I think that a lot of hybrid discs are probably mastered this way, though most discs' liner notes contain no information about how the cd layer was actually mastered.

As far as I know, there are no SACD's where the stereo program is just downmixed from the surround tracks. (I'm not even sure this is possible.) Some dvd-audio discs have been authored that way, though, even some that are labeled in a way that would make a consumer believe that a dedicated stereo program exists on the disc.

 

Thanks, that makes sense now. I always saw the blue-covered DSOFM. Didn't know it was SACD. Thought it was just another remaster. They had it for regular CD price (I guess) at Best Buy for $13.99. I grabbed it. I can never go wrong with this album, even though I've bought other reissues before

 

David, The SACD layer (stereo and 5.1) and the CD layer always have to be separate layers because they are each read by a different wavelength laser, you cannot mix them.

Also with respect to the 5.1 mixes remember that even though some older material was recorder on multi-track tape decks it was not recorded in a surround sound layout, they simply put different instruments and voices on different tracks and then mixed it down to stereo. This is why some of the 5.1 mixes of older material can have some very strange audio effects such as having the drums behind you when the singer is in front of you.

 

An interesting fact for all you nerds out there (me included!):


On the SACD layer, the Stereo SACD data is written from the inner edge outwards while multi-channel data (if there is any) is written from the outer edge inwards.

Check my posts in this thread to find out more about my findings.....

 

How is it possible that that the multi-channel data are written from the outer edge inward? The data are read during playback from the inner edge outward.

 

The SACD standard mandates that an SACD have a discrete stereo track.

 

Unless it is a mono only release. Many of my SACDs are simply mono hybrid, a mono mix on the redbook layer and the same mono mix on the SACD layer.

 

What makes you say that?

My findings indicate that the multiplexed Stereo (or in some cases 2-channel mono) pit track is read from the inner egde outward but that the multiplexed Multi-channel pit tracks is read from the outer edge inwards.

This finding is based on the spin speed during reading - did you read my posts in the other thread?

 

From your post on the other thread:

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The SACD format allows three variations in disc configuration.

(i) A single DSD layer
(ii) Two DSD layers (dual layer)
(iii) Hybrid disc (consisting of a single DSD layer and a single CD layer)

Out of curiosity, I assessed each of these types of disc and have some very interesting results!

Results:

(i) Carole King / Tapestry - Stereo only SACD

Disc spin speed decreases from beginning to end of DSD layer.


(ii) Thomas Schippers / Pictures At An Exhibition - dual DSD layer disc (Stereo DSD on one layer and Multi-ch DSD on the other)

Disc spin speed decreases from beginning to end of Stereo layer.

Disc spin speed increases from beginning to end of Multi-ch layer.


(iii) Pink Floyd / Dark Side Of The Moon - Hybrid disc

Disc spin speed decreases from beginning to end of CD layer.

Disc spin speed decreases from beginning to end of Stereo portion of DSD layer.

Disc spin speed decreases from beginning to end of Multi-ch portion of DSD layer.


These results seem to back up the following overview of the SACD format:

(i) If only one hi-res layer is used then the DSD data is written to "layer 1" from the inner edge outwards.

(ii) If two hi-res layers are present then the first portion of the DSD data is written to "layer 1" from inner edge outwards and the second portion of the DSD data is written to "layer 2" from the outer edge inwards.

(iii) If a hybrid disc is being made then the DSD data is written on "layer 1" from inner edge outwards and the CD data is written to the CD layer in accordance with the conventional redbook format specification (ie from inner edge outwards).


In the case of the discs used in this exercise it is would seem that on the dual layer hi-res disc, the stereo DSD data resides on "layer 1" while the Multi-ch DSD data resides on "layer 2".

In the case of the Hybrid disc, the stereo DSD data seems to be first on "layer 1" with the Multi-ch data following on the same layer.
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This seems to contradict what you are saying now? Unless you limit the statement to dual layer (not hybrid) SACDs?

 

Most mono CDs are "2-track mono", i.e. same content on both tracks. There have been some true mono CDs made, though (different mono content in each channel - a cacophony if you play them at the same time).

 

Apologies for being unclear. Luke is correct - my statement refers to the dual layer SACD (ie 2 hi-res layers).

Maybe I should read my own posts more carefully

 

None in my collection, so I can't give catalog numbers. But some classical reissue labels (e.g. Supraphon and Rodolphe) once did this, for playing times up to 160 minutes per CD. The practice fell out of favor (if it was ever in favor).

 

I always wondered why the redbook format didn't incorporate a flag for mono content telling the player to send on channel to both outputs, allowing the user to select which mono track to listen to.


Of course - it would rely on mastering engineers knowing how to master in mono without using a mis-aligned stereo playback headstack which as we know isn't always the case .

 

How many dual layer SACD's are there where both layers contain DSD encoded audio? I don't think I have any in my collection, but perhaps I'm mistaken.

 

This is impossible. For the data to be read from the outer edge inwards the disc would have to spin in the opposite direction!

 

My Pioneer DV-656A does this! In the CD playback menu you can choose stereo/right/left and when choosing left or right, it sends that one channel to both outputs (I've tried it and it works).

 

No. The spiral is written the opposite way.

This "spin direction" talk reminds me of a time when I naively tried to read a double-sided floppy disk using a double-sided drive. Should work, right? It didn't...because the double-sided disk was written on a single sided drive, by flipping the disk. Hence the tracks on the second side were going in the "wrong" direction. If somebody were to make a double-sided DVD player/writer, they would have the same problem.

 

I'll take your word for it. That being said, does anybody have a link to the SACD standard that explains double DSD layered discs? I didn't know they existed.

 

Not if the spiral is written in the opposite sense (as Luke has also pointed out). Here's what I wrote in the other thread:

------------------------------------------------
Take a DVD-Video disc. Suppose you have a dual layer disc containing a continuous program such as a film - the layer transition normally occurs around the
60 minute mark. We can assume that the reason for the transition is that we are close to the end of one side of the disc. At the transition, the data following on
from that on the 1st layer is read from the 2nd layer. From my experience with DVD-video discs I would say that the 2nd layer is written in the opposite
manner to the 1st layer. That is to say, if the 1st layer is read from the inner edge to the outer edge, then the 2nd layer is read from the outer edge to the inner
edge (this does not necessitate the disc to be spun in the opposite direction if the spiral track on the 2nd layer is configured in the opposite sense to that on the
1st layer). In this way, an (almost ) seamless transition is possible as the laser can pick up the new layer very close to where the previous layer ended.

One of the pieces of evidence that seems to back this idea up is that you are able to fast forward or rewind across the transition point without the laser sled
having to suddenly jump all the way across the disc each time the transition point is crossed. My player has a sealed drive unit so it is not possible for me to
verify this visually, but going on the sounds emanating from the player, this seems to be the way the discs are encoded.

On a closer examination of the spin speed (using my ears!) during playback of a DVD-Video disc, I now believe that the 1st layer is indeed written, as we both
might have expected, from the inner edge to the outer edge (OK, so I goofed in my earlier post ). However, the 2nd layer is, I believe, written from the
outer edge to the inner edge thus enabling the smooth transition between layers as described above.

If this is indeed the case, it means that the DVD format allows (if not requires) the 2nd hi-res layer to be written from the outer edge inwards.

---------------------------------------------------

Remember, the SACD is based on DVD specifications. Therfore, it is no surprise that for a dual layered SACD (ie 2 hi-rez layers) the two layers should be written in the opposite sense to each other just like on a dual layer DVD.

 

Search for:

["dual layer" hybrid "single layer" sacd]

on google and you will find many refernces to the 3 standard SACD disc types (type everything within the square brackets into the search box).

Here's the only thing I can find that corroborates my claims about the 2nd hi-res layer being written in reverse:

http://www.sonicstudio.com/pdf/dsd_sacd/sacdoverview.pdf

See Slide 7.

 

Irregardless of what Malc has said here, there is no such a thing as an SACD with two high resolution layers. If it is a single layer SACD it can contain both the 2.0 mix and the multi-channel mix on the same layer. And no, the machine does not mysteriously statrt playing backward to read the multi-channell mix. If the disc is a hybrid disc, then there are two layers; one redbook layer and one high rez layer. Again, the high rez layer of a hybrid disc can contain either just the single 2.0 mix or it contain the 2.0 mix and a multi-channel mix on the same layer.

 

Thanks for the link.

 

I have seen that information before but Malc S. is misunderstanding exactly what this is all about. The SACD format allows for a 2-layer high-resolution disc, which is different than a hybrid disc. This 2-layer high rez disc is only designed to increase the effective time and information storage capabilities of the disc. My understanding is that on these two layer discs (which I don't believe that any was ever manufactured except for a trail version of a Police concert), both the 2.0 mix and the multi-channel mix are contained on both layers, it is just cut in half to increase the storage capability of the disc. There were problems with that Police Live 2-layer SACD in that many machines could not read the first high-rez layer to get to the second high-rez layer underneath. My understanding is that the Police Live SACD was re-released in a 2 disc SACD package and the 2-layer SACD disc was re-called.