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Topic: Digital sound.

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 08-28-2007 06:34 AM

The Dolby-E portion of the DMA8 Plus is not impimented yet but will be once the firmware comes out of beta test...

As to the ProLogic...it is very hard for a decoder should pass the signal as PCM or go to ProLogic...only on AC3 and like sources will there be information in the metadata to tell a decoder what to do. Furthermore, Cinemas calibrate their surrounds 3dB lower (82dBc/side) than everyone else (85dBc/side). The DMA-8 is supposed to look for flags to compensate for that but rarely do any sources have those flags set except conventional consumer sources like DVDs. On several installations now I have line amplifiers to deal with the 3dB difference and have been begging Dolby to provide for forcing the surround level change as a user option. Their concern being that it will ALWAYS be boosted since "more surrounds is better."

Most "professional" video tracks are indeed mixed 2-channel stereo as that is what they have in their video suites. However, that does not translate well to the big screen when 10s of feet exist between left and right speakers. I always force a prologic decode on such programs unless the person who made the video is present and throws a hissy-fit about it.

The DMA8 makes this a bit too complicated to do (need a computer or means of RS232 commands) which is why I prefer the Dolby DP564.

Stephen, are you using all of your inputs? If not, perhaps you could use a DA to send the 1/2 pair to both the 4xAES and to one of the remaining stereo inputs...set one to prologic all the time and leave the 4xAES discrete.

Alternately, you could use something that would spit out the necessary RS232 commands to control the DMA8 Plus. Look at Mediatech. They have button panels that will spit out whatever you program into them.

Steve

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002

posted 08-28-2007 04:01 PM

quote: Steve Guttag
The Dolby-E portion of the DMA8 Plus is not impimented yet but will be once the firmware comes out of beta test...

I was not aware of that; the manual says nothing to indicate that it's not fully implemented yet. I don't have any Dolby E encoded material to test it with, and probably won't have in the future either.

quote: Steve Guttag
As to the ProLogic...it is very hard for a decoder should pass the signal as PCM or go to ProLogic...only on AC3 and like sources will there be information in the metadata to tell a decoder what to do. Furthermore, Cinemas calibrate their surrounds 3dB lower (82dBc/side) than everyone else (85dBc/side). The DMA-8 is supposed to look for flags to compensate for that but rarely do any sources have those flags set except conventional consumer sources like DVDs. On several installations now I have line amplifiers to deal with the 3dB difference and have been begging Dolby to provide for forcing the surround level change as a user option. Their concern being that it will ALWAYS be boosted since "more surrounds is better."

Yes, the decoder switching is going to be manual for PCM material, and ours is turned on, since if I feed it 'real' 2-channel PCM material, this is decoded. This is what leads me to think that in the case of the two 'problem' films, the DMA thinks it is getting a multi-channel track, even thoough only two of the tracks actually have any sound on them.

quote: Steve Guttag
Most "professional" video tracks are indeed mixed 2-channel stereo as that is what they have in their video suites. However, that does not translate well to the big screen when 10s of feet exist between left and right speakers. I always force a prologic decode on such programs unless the person who made the video is present and throws a hissy-fit about it.

If you drop the 's' off the end, and just make that 10 feet, thin you're not far off the size of our screen, but even at that size the 'hole in the middle' is noticeable from some seats.

quote: Steve Guttag
The DMA8 makes this a bit too complicated to do (need a computer or means of RS232 commands) which is why I prefer the Dolby DP564.

What is the DP564?

quote: Steve Guttag
Stephen, are you using all of your inputs? If not, perhaps you could use a DA to send the 1/2 pair to both the 4xAES and to one of the remaining stereo inputs...set one to prologic all the time and leave the 4xAES discrete.

Alternately, you could use something that would spit out the necessary RS232 commands to control the DMA8 Plus. Look at Mediatech. They have button panels that will spit out whatever you program into them.

Digital 2 is free at the moment, but likely to be used in future. Was it you, in the past who said that the digital 1 input is 110 Ohm balanced? If that is the case then we would need a matching transformer. Then there is the problem that somebody who only projects there occasionally my be confused by digital cinema content coming in on two different inputs. This might be worth considering if we get more films like this in future, but maybe it was an error, and we won't get any more.

A device to send RS-232 commands won't help, since the decoder 'on' setting has already been made; it's just that i doesn't work with this particular content.

While you're begging Dolby to do other things how about begging them for an option to select any one of the four pairs on digital 1, ignore the other three pairs, and put the chosen pair through the matrix decoder if you choose to do so. It should be a fairly minor software modification I would have thought. Also, they could allow whichever pair was selected to be decoded as Dolby Digital, or Dolby E, not just the first pair.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 08-28-2007 06:58 PM

Forget it...it is apparently intrinsic to the design that the 4xAES input only works off of pair 1/2 for its magic. To the point that if pair 1/2 don't exist or are disconnect, the other lines will NOT pass through.

Yes, the 4xAES is 110-Ohm balanced...aka AES3...aka AES-EBU. You would need a DA in addition to the matching transformer...trust me, the DA was the pricy thing in the deal.

As for confusion, that is as easy as a label. On one you have "discrete channels" and the other you have "Pro-logic".

If you have the DMA8 set for prologic and it gives you discrete...would imply that it is seeing an AC-3 signal that is encoded 5.1 with only Left and Right active...a prologic decode is a prologic decode. Now it could be that if it senses audio on the other channels it presumes discrete (automatic).

The DP564 is Dolbys reference PCM decoder and one of their better products though it is "broadcast" and not generally available for cinema. It is a shame too since it is a marvelous piece that has alternate content application.

DP564 page at Dolby

The DMA8 Plus shipping firmware is 1.3.2.3. Neither Dolby-E nor 96KHz PCM are implemented yet. I have a unit waiting for the Dolby-E part before being installed...been waiting about a year now! The Dolby-E is in beta test now...I want them to get through with that before installing it...I don't need to find their problems on this particular installation. I hear the release is coming soon though.

Steve

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002

posted 08-29-2007 03:27 AM

quote: Steve Guttag
Forget it...it is apparently intrinsic to the design that the 4xAES input only works off of pair 1/2 for its magic. To the point that if pair 1/2 don't exist or are disconnect, the other lines will NOT pass through.

That makes sense; I remember now that somewhere in the manual it says that the clock for all pairs is always taken from pair 1; so no pair 1, no clock.

quote: Steve Guttag
Yes, the 4xAES is 110-Ohm balanced...aka AES3...aka AES-EBU. You would need a DA in addition to the matching transformer...trust me, the DA was the pricy thing in the deal.

As for confusion, that is as easy as a label. On one you have "discrete channels" and the other you have "Pro-logic".

It might be an option to consider if we do get more films like this.

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002

posted 09-23-2007 07:56 PM

Steve said, "The Dolby-E portion of the DMA8 Plus is not impimented yet but will be once the firmware comes out of beta test...."

On the off chance anyone who cared didn't know...:

quote: Dolby/Ken Jacquert

Date: Sun, 23 Sep 2007 17:29:14 -0700

For your information, there is a new production release of DMA8Plus firmware and setup software. We recommend that you download these latest files [...], install this latest setup software on your laptop, and upgrade your DMA8Plus units at your convenience.

The new DMA8Plus setup software is version 1.2.9.0. This version includes the latest fixes, sample rate display, support for setup software connections through a firewall, and includes a built-in "Dolby Software Update" to be used for upgrading your unit to the latest firmware version (via the "Action" menu).

The new DMA8Plus firmware is version 1.4.1.9. This version includes the latest fixes, 96kHz PCM (Tru96 processing), support for setup software connections through a firewall, and support for Dolby E decoding.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 09-23-2007 11:26 PM

Not that Dolby wouldn't want the information passed on...but your quoted text John looks like it came from a private email which all Dolby emails have a proviso at the bottom that nothing in the email is to be disclosed publically.

I believe what is currently available is a "public beta" of what should become the release version for the DMA8 Plus. This is the last stage of beta to broaden the range of testers and see if they got all of the little things right.

Steve

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002

posted 09-24-2007 12:21 AM

Wow, Steve, I almost never read those things, I'm afraid I've gotten inured to them. Thanks.

But in point of fact, it actually says, "If you are not the intended recipient, delete this message. If you are not the intended recipient, ..." So as long as you are the intended recipient, you are not enjoined from further distribution. I think that makes it fine in this case. (That is, the disclaimer is intended to deal with people intercepting e-mail, not to prevent the legitimate recipient from sharing it.)

--jhawk

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 09-24-2007 08:41 AM

Most any "technology" company puts restrictions on discussing their propritary information with others. Again, I doubt that Dolby would not want it known they have the DMA8 Plus fully functional.

After one has signed enough "NDAs" (Non-Disclosure Agreements) and are constantly dealing in non-released information, I tend to be very reserved in posting such information and instead have the manufacturer make such posts so everything is above board.

I think you are fine on this one though...as you pointed out...nothing said anything about non-disclosure of the info contained in the email.

Then again, there is this site's rule #6 about posting information in an email unless specific permission was given to post it (as opposed to specific instructions for non-disclosure). [Wink]

Steve

PS Cue markers?

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David Graham Rose
Expert Film Handler

Posts: 187
From: Cambridge, UK
Registered: Sep 2002

posted 09-24-2007 12:44 PM

Quote Stephen Furley
"I noticed something strange about the sound on 'Becoming Jane', which I think was the second digital film we ran. The lights on the DMA were showing nothing on the Ls and Rs channels, but there was a signal much of the time on the normally unused channels 7 and 8. Despite this there was sound on the surround speakers."

Greetings

In the UK track 7 and/or 8 often has audio description narration for the visually impaire.

David

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