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Hear Dolby Digital decoding on G5s with Logitech Z680 System
When I ordered my G5 several months ago, I also included the Logitech Z680 surround sound speaker system. The system has an optical input and the G5 has an optical output so I figured it was a good match.

For those of you unfamiliar with the Z680 system, it has a built-in Dobly Digital 5.1 surround decoder. So if you feed it the proper encoded signal, it will decode it and provide true Dolby 5.1 surround sound. They also have standard analog inputs as well. Only the optical interface, however, can carry a Dolby Digital encoded signal. If you use the analog input, the system uses a synthesised 'faux' surround scheme called Dolby Pro Logic, which takes a non surround signal and makes best guesses as to which speakers to send the sound. But this generally is not very good.

Anyway, when I finally got everything hooked up optically -- you need to buy the optical cable as it is not included in the Z680 or G5 box -- I launched DVD player (v3.3) and waited for the beautiful true Dolby Digital 5.1 surround. It never happened. The system -- which has an LCD status display -- would only enter into the simulated Pro Logic mode. This meant it wasn't getting the properly encoded signal. I checked the Sound System Preferences to make sure the output was set to 'Optical digital-out,' which it was, but still no luck.

I was about to resign with the notion that this feature was only going to come with Panther, as I had read some things about true S/PDIF support in Panther, when I discovered in the DVD Player preferences, under the Disc tab, a pop-down list labeled 'Sound Type.' Popping this list down, I was presented with two choices 'System Sound Output' which was the currently selected choice, or 'Digital Out - Built in Audio.' I selected the latter, started playing my Vanilla Sky DVD and, voila!, the speaker status display jumped to Dolby Digital and I was indeed getting true Dolby Digital 5.1 surround!

I hope this is helpful to people. I checked around and I didn't see a similar hint. Also, while searching it seems like a large number of people don't believe true Dolby Digital is supported in pre-Panther systems, so I figured it was worthwhile.
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Hear Dolby Digital decoding on G5s with Logitech Z680 | 8 comments | Create New Account
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Hear Dolby Digital decoding on G5s with Logitech Z680
Authored by: JohnITG on Oct 21, '03 12:31:57PM

It works in 10.2.8 on my G5DP... I have a Midiland 8200 using the optical out and was having the same problem until this tip. Turned on optical put in a DVD and AC-3 came up on the controller. I am using my 4 monsoon flat panel speakers and a Boston for the center. Now if I just keep the windows from breaking!



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Hear Dolby Digital decoding on G5s with Logitech Z680
Authored by: Durandal on Oct 21, '03 12:44:55PM

Actually, Dolby Digital is supported in pre-Panther systems through VLC, if you have a Revolution 7.1 sound card and a set of 5.1 analog speakers. Turn off all the fake surround stuff and VLC will process and decode the AC3 stream to the appropriate speakers. This only works if they are 5.1 speakers. 4.1 systems will have their left front channel designated as the center channel. The VLC people could probably just tell the front speakers to emulate a center channel though, so I expect that VLC will eventually be able to do full surround on 4.1 and 5.1 systems.

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Damien Sorresso



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Dolby Pro Logic IS surround sound
Authored by: mclayville on Oct 21, '03 03:12:04PM
Dolby Pro Logic is NOT a synthesized "faux" surround scheme. It is a second generation surround sound decoding system developed by Dolby Labs, the first generation being Dolby Surround. See this Dolby whitepaper for a little history on the subject. Next time try to get your facts straight.

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Dolby Pro Logic IS surround sound
Authored by: clallo on Oct 21, '03 04:15:41PM
Geez. You don't need to get nasty! While Dolby Pro Logic II *can* decode Dolby Surround encoded sources, its biggest innovation is it's ability to *generate* a 5.1 surround field with from normal stereo input From The Dolby website:
"Pro Logic II from Dolby Laboratories gives you multichannel surround sound from any stereo source—CDs, tapes, videocassettes, TV broadcasts, AAC files, you name it. No matter if you're listening to Stravinsky, the Stones, or a Schwarzenegger movie, you'll get the realistic, involving sound you'd expect from a 5.1-channel system. Pro Logic II brings all of your old audio software into the 21st century, giving you many of the benefits of Dolby Digital from ordinary stereo software. With its elegantly simple circuitry and the smoothest steering logic ever, it's a very rare processor indeed—the kind you'll want to leave on all the time, so you can always enjoy surround sound, no matter what the source. Probably the most innovative feature incorporated in most receivers is the Music mode, which creates a rich and enveloping surround ambience from stereo sources such as CDs. ... An optional Matrix mode can be included to produce surround sound from mono material.
So I don't really know how I didn't "have my facts straight". Perhaps this is a case of the pot calling the kettle black? Regardless, the point of the hint was how to enable true Dolby Digital 5.1 surround via the Optical output of the G5 and DVD player 3.3. And in that regard, it appears to already have already helped someone.

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Dolby Pro Logic IS surround sound
Authored by: Durandal on Oct 21, '03 05:46:43PM

Dolby ProLogic is a method of encoding multiple channels into 2 stereo channels. Receivers which cannot decode ProLogic will just pick up the two stereo channels and that's it. It's not "fake" surround sound. It's just a more primitive form of it than Dolby Digital, which can support more than 2 discrete channels.

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Damien Sorresso



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Hear Dolby Digital decoding on G5s with Logitech Z680
Authored by: clallo on Oct 21, '03 04:30:26PM
Geez. You don't need to get nasty! While Dolby Pro Logic II *can* decode Dolby Surround encoded sources, its biggest innovation is it's ability to *generate* a 5.1 surround field with from normal stereo input From The Dolby website:
"Pro Logic II from Dolby Laboratories gives you multichannel surround sound from any stereo source—CDs, tapes, videocassettes, TV broadcasts, AAC files, you name it. No matter if you're listening to Stravinsky, the Stones, or a Schwarzenegger movie, you'll get the realistic, involving sound you'd expect from a 5.1-channel system. Pro Logic II brings all of your old audio software into the 21st century, giving you many of the benefits of Dolby Digital from ordinary stereo software. With its elegantly simple circuitry and the smoothest steering logic ever, it's a very rare processor indeed—the kind you'll want to leave on all the time, so you can always enjoy surround sound, no matter what the source. Probably the most innovative feature incorporated in most receivers is the Music mode, which creates a rich and enveloping surround ambience from stereo sources such as CDs. ... An optional Matrix mode can be included to produce surround sound from mono material.
So I don't really know how I didn't "have my facts straight". Perhaps this is a case of the pot calling the kettle black? Regardless, the point of the hint was how to enable true Dolby Digital 5.1 surround via the Optical output of the G5 and DVD player 3.3. And in that regard, it appears to already have already helped someone.

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Hear Dolby Digital decoding on G5s with Logitech Z680
Authored by: Accura on Oct 21, '03 06:52:35PM

Lucky you, the opening scene in Vanilla Sky is lush to watch with 5.1

we watched it the other day using a PS 2 and the logitech z680s.

"OPEN YOUR EYES!!!"

Now all i need is a G5 with optical out.. hmmmm

Congratz on the great hint

jameso

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"The time has come," the walrus said. "To talk of many things..."



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Hear Dolby Digital decoding on G5s with Logitech Z680
Authored by: veshman on Oct 21, '03 09:11:31PM

this is a great hint...most people think that the DVD player does not support 5.1.

of course, this is fixed in panther..but it's still great news for people who aren't upgrading.

bhavesh



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