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Digital Audio via Receiver

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January 29, 2005 8:41:13 AM

Hello, this is my first post here, mostly just to address the issue of SPdif sound output and Dolby digital surround sound. First I will admit I am haven't had the chance to experiment with every soundcard and device out there so I will keep my statements based on what references I have.

My issue is this, that Dolby digital surround sound, 5.1 format does not get sent out to DD and DTS receivers via spdif. Let me explain.

Once upon a time as I was coming into my own as a computer tech I built myself a system for the first time useing the Nforce2 platform. This platform had the MCP-T APU that allowed both DTS Decodeing and ENCODEing. I hooked it up via coax to my digital Receiver and voila, 5.1 surround sound. I did the sensaura test and the music ball glided seamlessly all around me.

Since then, my audio life has been hell. After selling that system I have NOT been able to recreate that effect with ANY hardware setup. AC97? Please.. I'v tryed Turtle beach soundcards, I'v tryed an AUdigy 2 soundcard. Neither seem interested in sending a signal my receiver understands as being in dolby digital format.

After alot of research into audio I have learned a few things. 99% of the audio market uses PCM or AC3 audio signal to output to Receivers via spdif. PCM and AC3 both basicly mean "CD quality, 2 channel audio" Voila, problem answered. Not even creative labs has had the brains to design a soundcard that ENCODES the analog signal it produces into a digital format that Receivers can read as being multichannel. Receivers will tell you when they are getting such a signal as the word will light up, typically in red, "Dolby digital".

If your not seeing that message, your not getting the real thing.

So the problem now is, is there ANYTHING on the market today aside from the MCP-t version of Nvidias soundstorm APU that does the kind of analog to digital encodeing required to properly use ones own home audio system?

More about : digital audio receiver

January 29, 2005 8:39:16 PM

As far as I know sound cards only have Dolby Digital Passthru (I guess DTS should be possible, but I don't know that). All most all sound cards have this feature. You can send 5.1 from your DVD and video files to you Receiver but games/applications can't do the same. As you said, there are no Dolby Digital or DTS encoders built into sound cards.

There is good news. It's rumored that Soundstorm will make a return but in a different form. It will be incorporated into the GPU on nVidia video cards.

<b>A mind is a terrible thing</b>
January 30, 2005 6:44:26 PM

Since I never really watch DVD's I guess I would never have noticed the pass-thru function. Ah well, thats better at least. I now have a reason to buy a soundcard aside from getting better framerates. 0o
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January 30, 2005 7:07:55 PM

Actually, pretty much all of today's cards/motherboards have that passthru feature, assuming they support some form of SPDIF output.

It's only the old 2 channel sound cards that might not support the feature, and that's only a guess.

Come to think of it, 5.1 is encapsulated within SPDIF encoding. Maybe all cards support the passthru because they really don't have any control over it.


<b>A mind is a terrible thing</b>
January 30, 2005 7:59:57 PM

The only sound card I can think of that has 6 channel (5.1) spdif output is the audigy 2zs platinum pro. I think the spdif output on previous cards was proprietary to creative speakers. Creative likes to be proprietary :( 

<A HREF="http://www.folken.net/myrig.htm" target="_new">My precious...</A>
January 31, 2005 8:22:14 AM

Your right about that pass-thru function, its actually a function of software so long as there is a SPdif.

Now things come into view why for so long there has not been a encodeing feature on soundcards. Who needs it when you get the pass thru on moves and music doesn't require it. So Gamers just get stuck having to settle with analog for their surround sound needs. Sucks since games use surround sound more intensivly then anything else.

I'v looked at the specs and all on the Platinum Pro, Folken and It does not do as you say it does unless I am missing something. It features digital to analog decodeing for music playback. The exact opposite of what I want. LOL I want Analog to Digital Encodeing for playback of game audio in digital format to my receiver. Till then I will have to switch between my spdif and 6ch inputs.

Thanks for the info on pass-thru btw.
January 31, 2005 7:24:18 PM

Eh, I'm not much of a sound system guru yet. I had no idea games put out analog sound :(  I figured if it is in the computer it must be digital, lol. When I read some reviews for the platinum pro it said 6ch digital spdif output. I guess it (and most other cards) can put that out but if it isn't already in that format it wont.

I guess you will have to live with analog output to your reciever. I'll bet analog output from an audigy is still better than soundstorm ever was, lol. I have a klipsch promedia 5.1 system and going from soundstorm to audigy was like night and day. It was like I was watching my movies and playing my games for the first time all over again.

<A HREF="http://www.folken.net/myrig.htm" target="_new">My precious...</A>
February 4, 2005 5:31:43 AM

The nVidia soundstorm is currently the ONLY sound card that can create 5.1 Dolby Digital output. Its largely the same design used in the X-Box and Microsoft wanted a gaming system 5.1 digital output.

Most other cards can encode 2 Dolby Digital channels, even if they are capable of outputing 7.1 analog channels.

So for now if you want 5.1 from games you need to use an NForce 2 motherboard with the SoundStorm ACU, or you need to connect via analog outputs.

On the bright side even the cheapest $20 C-Media card with digital out has no problem passing though an existing Dolby Digital-EX/DTS-ES ect stream.

They also seem to do an excellent job creating 2ch AC3 signals, so you should not notice any difference between a C-Media and a Audigy 2 ZS when listening to MP3's via digital output.




<P ID="edit"><FONT SIZE=-1><EM>Edited by Codesmith on 02/04/05 03:51 AM.</EM></FONT></P>
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