SACD layer

David, I do not know of any personally since I am only into rock and blues, but it is allowed, I will send you a .pdf on it if I can figure out how to.

I see the link already has what you need.

 

Rocky,

with all due respect you are wrong (although I accept that I am also guilty of reaching conclusions which are not entirely correct - read on....).

I own a mass produced SONY Dual Layer SACD which comprises of two hi-res layers (and no CD layer).

The disc in question is "Prokofiev and Mussorgsky - Schippers" on Sony Classical SS87711. It has both stereo and Multi-channel SACD. The stereo and multi-channel content are both just over 74 minutes long.

I decided to check my claims about this disc being dual layer more thoroughly so I removed the lid and watched the laser mechanism during playback on my SCD-XE670.

My findings are that this disc is indeed dual layer (ie two hi-res layers) and that the second layer is indeed written from the outer edge inwards just as in the DVD-9 standard.

Where I was incorrect is that the first 20 minutes or so of multichannel data is written straight after the stereo data on the first layer and the transition between layers actually occurs about 20 minutes into the multi-channel program (at 2' 3'' into the 5th track of the multi-channel program for those interested). At this point you can hear the laser mechanism re-focussing and then it starts to move back towards the centre of the disc for the remaining 55 minutes of music. The transition point is actually about 1 cm from the outer edge of the disc for this particular SACD.

As I have said - there is at least one commercially available dual layer disc and I imagine there are others.

It is clear from my findings that if more capacity is required for hi-res data than is available on a single layer, a second hi-res layer is used. The data is written from the inside out for the first layer and from the outside in for the second layer (as in DVD-9). Any music data will be written pretty much contiguosly (notwithstanding cross-interleaving) so your concept of the data arrangement on a dual layer disc is not accurate.

Incidentally, there is no SACD standard for a 3 layered disc comprising 2 hi-res layers and a CD layer (this would preumably run into the same manufacturing/compatability problems that the backward compatible hybrid DVD-Audio attempts did). This would explain why the Dylan - Blonde On Blonde hybrid release was spread over 2 discs. A single disc would run to around 70 minutes for both the stereo and multi-channel SACD content which would require the single disc to contain 2 hi-res layers as well as the CD layer which, as we have seen, is not an option.

 

David,

here's a better link for you:

Sony white paper download page

Click on the link on this Sony site to download a .pdf of their white paper on the SACD format. Page 7 has the information about the different disc types allowed.

 

Thank you Malc for the information, and I will definately look more into this phenomenon with an open mind!!!

 

There are a number of Sony multi-channel non-hybrids SACDs with two DSD layers. They are easy to spot by looking at the playing surface side by side with a single layer SACD - they are a different colour. They also have two numbers around the ring.

 

Hey Geoff,

I guess I've finally settled our old argument about the 2nd SACD layer being written from the outer edge to the inner edge having now seen the indisputable evidence with my own eyes .

Malc

 

I recall the discussion. I wish I could find a technical paper that agreed with your personal observations.