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SteveCZ  
#1 Posted : Sunday, March 23, 2008 7:31:49 AM(UTC)
SteveCZ

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Hi! Very much interested in the Opus DAC (or, more likely, the upcoming Buffalo DAC, assuming it turns out well).

A significant problem is getting high-res digital data (DVD-Audio, SACD, etc.) from a dvd player to the converter, given the paranoid copy-protection schemes on the player's outputs. I'll be buying a new player soon, and I am not quite willing to hack the insides of a player under warranty (or confident in my abilities to do so, having seen some of the discussions).

Would the new HDMI standards work for getting the info to the DAC? Either by using an external device that duplicates the HDMI signal and extracts the audio, or by an input module (that I certainly could not design) for the DAC that would do roughly the same thing?

Here is one example of an external device:

http://www.octavainc.com...plitter_5x2_toslink.html

Perhaps it (barring the existence of an HDMI input module) would be a solution to this problem?
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Russ White  
#2 Posted : Sunday, March 23, 2008 7:38:28 AM(UTC)
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It would be interesting to buy one of the boxes and see if the TOSLINK output works while playing SACD.

In any case, if it does, then they paid a licensing fee (and went through the approval process) to use the decoder part. If it does not, then they are in the same boat as us... :)

Cheers!
Russ
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SteveCZ  
#3 Posted : Sunday, March 23, 2008 11:06:02 PM(UTC)
SteveCZ

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Thanks for the response, it is a maddening problem.

As far as external box solutions go, here is another possible one from Gefen:

http://www.gefen.com/kvm/product.jsp?prod_id=3939

In a Gefen forum discussion, an admin said that the Toslink output there would put out 192kHz for 2 channels.

He said it would not do native DSD, because Toslink doesn't have enough width. Not sure about that, I thought that 24-bit, 192kHz was equivalent to the width required for SACD. I've emailed Octava and Gefen to ask exactly what gets put out from the Toslink when it is fed from a SACD.

Anyway, here is the forum discussion:

http://forum.gefen.com/topic.asp?TOPIC_ID=2533
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Russ White  
#4 Posted : Monday, March 24, 2008 4:54:56 AM(UTC)
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Well, an SACD player with HDMI out will not output PCM for SACD playing (unless it does some sort of DSD to PCM conversion). Some DVD audio player already output the PCM via SPDIF, so don't need a special box for that.

192/24 PCM for 2 channels is simply the highest supported sample rate for that box, but that PCM will only be there if the upstream device puts it there, which is not likely at all.

To get true SACD DSD the easiest way is simply to hack on old SACD player and take the DSD out to your own DAC.

Cheers!
Russ

Edited by user Monday, March 24, 2008 4:56:46 AM(UTC)  | Reason: Not specified
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Russ White  
#5 Posted : Monday, March 24, 2008 5:32:56 AM(UTC)
Russ White

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Just to clarify, while many players do support DSD over HDMI, that DSD payload is still encrypted, it is required by the specification. Also any DSD would not be output via SPDIF by a splitter.

If someone can show me differently I will be very pleased. :)

Cheers!
Russ
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SteveCZ  
#6 Posted : Wednesday, April 2, 2008 5:40:51 PM(UTC)
SteveCZ

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Hi again!

I received some responses to questions from the Gefen people. I'm still not sure what it means, regarding encryption and the myriad details that seem to be needed for a real solution, but it at least seems slightly hopeful.

I asked:

Dear Gefen,

I am interested in using your HDMI to DVI Audio Adapter in my home theater
setup. I have a question concerning the units capabilities.

When a high-resolution andio source is being sent to the adapter via HDMI,
what does the Toslink output consist of? In other words, when my DVD
player is outputting a high-resoluton audio signal to your adapter from a
SACD (or DVD-Audio) disk, does your adapter's Toslink connection output
the full-resolution DSD (or 24bit/96kHz PCM)? Or, will a lower resolution
audio signal be sent out via Toslink?

Thank you.


Gefen support replied:

The Toslink output will output the full resolution.

Thank,


I then asked, more specifically:


Thank you for your response! The adapter really seems like it might meet
my needs.

One more question:

How is the output configured for stereo/multitrack audio? In other words,
if a 5.1 channel DSD signal is being sent over the HDMI output, what will
be outputted by the Toslink connector? All 6 channels in DSD? Or the R
and L front channels in DSD? Something else? And is the situation
similar for multichannel DVD-Audio signals?

Thanks.


Gefen support responded:

You will get all 6 channels of 5.1 audio sent over the HDMI output which
would then send it over the Toslink connector.

Thanks,


Just to be clear, the unit I was asking about is: http://www.gefen.com/kvm/product.jsp?prod_id=3939
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Russ White  
#7 Posted : Wednesday, April 2, 2008 5:47:10 PM(UTC)
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I think anything over SPDIF is going to be PCM. So there has to be some conversion.
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SteveCZ  
#8 Posted : Wednesday, April 2, 2008 6:27:03 PM(UTC)
SteveCZ

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Also, the bandwith limitation assertion re:DSD and Toslink is a myth. The modern Toslink spec is 150 Mbit/sec, which can easily handle many 2.8 Mbit/sec DSD strands.
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SteveCZ  
#9 Posted : Wednesday, April 2, 2008 6:34:11 PM(UTC)
SteveCZ

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Well, probably you are right. As I think about it, what commercially available product would a Toslink DSD feed serve? The purpose of the box seems to be for people to connect to a receiver and projector. I don't know of any receivers that would take a Toslink input of DSD, even if such is possible.

Sigh.

It is frustrating that these companies do not put out coherent specifications for their devices. At least the Gefen people did respond to emails.

For people who do not want to hack a player (it just sounds intimidating), even a detachable hi-rez pcm feed might be really nice...especially if the DSD goes to 24bit/192kHz (which is what professional editing platforms sometimes convert DSD to for editing/processing).
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Russ White  
#10 Posted : Thursday, April 3, 2008 10:50:36 AM(UTC)
Russ White

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Sure, and anyone who wants to could easily use that device to feed our SPDIF module into OPUS/COD or directly into Buffalo with no SPDIF module required as it accepts SPDIF directly. We also have a nice TOSLINK input module that can handle 192/24 audio.

Cheers!
Russ
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