Gaming 3D sounds and Dolby decoder compatibility

[Kreshna Aryaguna Nurzaman]

Alright, Mike may be interested in this

Alright, there are some 3D sound standards used in computer gaming environment like Aureal 3D, QSound, or Direct Sound 3D. Most standard gaming setups is to connect the double stereo outputs from those soundcards to powered (cheap) 5.1 speakers, like those provided by Altec Lansing or Creative.

On the other hand, on (Dolby standards) home teather setup, typically we connect various sources (DVD players, etc) to a dedicated Dolby decoder, then to amplifiers, then speakers.

Now, what if we connect the sound card output into a dedicated Dolby decoder? Are those PC 3D sound standards compatible with any kind of Dolby standards?

For instance, if we are playing WarCraft III which is using EAX 3D Positional Audio, then connect our soundcard to a Dolby decoder (instead of cheap, powered speakers), can the decoder recognize and decode the 3D audio signal properly? Can we enjoy WarCraft III 's 3D "surround" sound *properly* in such setup?

Also, I'm not really familiar with 3D standards used in PC environments. Are they more like Dolby ProLogic (mixing front and rear signal through single channel, thus allowing us to hear "four-channels" surround through conventional stereo (L/R) connection), or do they actually have much different way of signal processing? (Thus, incompatible with any Dolby standard)

And how about dts?

[Vertigo1]

I've connected my computer to the home theater system downstairs via spidif (coaxial audio) without any problem and it played the audio properly.

[phongn]

Your sound card will need to encode the game's audio into a Dolby Digital stream, which you can then pipe out to some DD decoder. AFAIK, only nVidia's SoundStorm (integrated on some Athlon motherboards with the nForce 2 chipset) could do this.

[Kreshna Aryaguna Nurzaman]

Your sound card will need to encode the game's audio into a Dolby Digital stream, which you can then pipe out to some DD decoder. AFAIK, only nVidia's SoundStorm (integrated on some Athlon motherboards with the nForce 2 chipset) could do this.

That's the sound card (using S/PDIF cables and such, IIRC), how about 3D sound standards used by some games? Are they compatible with Dolby?

EDIT: is the sound card capable to "translate" common gaming 3D standard like Aureal 3D or DirectSound 3D into Dolby Digital format? And how about some products claimed to be "dolby-capable" like SoundBlaster Live! ?

[Kreshna Aryaguna Nurzaman]

I've connected my computer to the home theater system downstairs via spidif (coaxial audio) without any problem and it played the audio properly.

What's the sound card are you using?

[Kreshna Aryaguna Nurzaman]

Shit, I just read this from Gaming Force Forums

However, there is a downside to using home theater speakers with your PC. With PC speakers, the analog outputs from your sound card are usually directed through your subwoofer or a decoder box. These devices examine the front channels and remove all of the sound below a certain frequency, called the crossover, then redirect it to your subwoofer (a process called bass management). They do this because games do not separate the bass from the other channels; they just send it all to the sound card, which does not have enough power to properly manage the bass by itself. Home theater speakers don't do this because they are connected to a receiver that handles this job. Unfortunately, most receivers can only apply bass management to digital or stereo analog inputs. If you're using 5.1 analog connections from your sound card, your receiver will not manage the bass. That means you either let the sound card do it or you have no bass.

Anyone knows any dolby receivers capable to do bass management from 5.1 analog input?


PS: On the other hand, I think these combination will work to hear surround sound from games:
- old soundcards (which only have stereo analog output, like AWE32).
- old games that support Dolby Surround (like Assault Rigs, or IIRC F-22 Raptor).
- Dolby Surround-capable receiver.
It is because Dolby Surround can send "surround" signal through stereo analog receiver, right? (though as not as good as Dolby Digital)
Has somebody managed to succesfully play games with surround sound with the above setup? How about newer games with EAX or A3D??

[phongn]

Dolby Surround (and Pro Logic and Pro Logic II) use mathematical algorithms to "fake" surround sound from only two channels of information.

Even if your receiver is capable of decoding Dolby Digital it doesn't neccessarily mean that you can simply use digital out from your computer to digital in on your receiver or pre/pro. The signal must first be encoded from A3D/EAX/DS3D or whatever into Dolby Digital, at which point the receiver can understand it.

If your sound card is incapable of DD encoding at best you will be outputting two-channel PCM to the receiver or pre/pro. You may be able to get "faked" surround sound from that.

Now, as for the analog 5.1-7.1 input stages virtually every pre/pro and receiver on the market will have those completely bypass any sort of digital sound management function. This includes bass management. This does not mean that you will have no bass, only that the receiver or pre/pro will not do some crossover functions for you internally.

(Note: pre/pro means preamp/processor. Receivers are typically a combination of processor (decodes surround-sound information), preamp (volume control and device selector) and amplifier).

[phongn]

That's the sound card (using S/PDIF cables and such, IIRC), how about 3D sound standards used by some games? Are they compatible with Dolby?

You are confusing the internal algorithms such as EAX, A3D or DS3D with methods used to actually reproduce the sound in a multichannel format (such as Dolby Digital [DD] or DTS).

EDIT: is the sound card capable to "translate" common gaming 3D standard like Aureal 3D or DirectSound 3D into Dolby Digital format? And how about some products claimed to be "dolby-capable" like SoundBlaster Live! ?

There are no sound cards on the market that can do that. Some nForce2-based motherboards had that ability (called SoundStorm) but it has not re-appeared since. With the increasing availability of PCI Express motherboards we may well see it, however (DD encoding is bandwidth-hungry).

Virtually every other card claiming to by "Dolby Capable" probably means that it can pass through a Dolby Digital signal (say, from your DVD-ROM) to SPDIF-out.

[Darth Wong]

Anyone knows any dolby receivers capable to do bass management from 5.1 analog input?

I've never heard that referred to as "bass management" before. But I always thought 5.1 analog was a crazy idea anyway; anyone who wants serious-quality sound from a computer will use digital. Who the hell needs a shitload of audio cables running from a computer to a home theatre system, and who wants to use the DAC in a soundcard anyway?

PS: On the other hand, I think these combination will work to hear surround sound from games:
- old soundcards (which only have stereo analog output, like AWE32).
- old games that support Dolby Surround (like Assault Rigs, or IIRC F-22 Raptor).
- Dolby Surround-capable receiver.
It is because Dolby Surround can send "surround" signal through stereo analog receiver, right? (though as not as good as Dolby Digital)
Has somebody managed to succesfully play games with surround sound with the above setup? How about newer games with EAX or A3D??

EAX and A3D have nothing to do with the protocol used to output sound to the receiver. Ideally your soundcard should have Dolby Digital output, which you can pipe to a Dolby Digital receiver. Failing that, just use ordinary stereo analog outputs; is computer surround sound really that important?

[Durandal]

Dolby Surround (and Pro Logic and Pro Logic II) use mathematical algorithms to "fake" surround sound from only two channels of information.

Yes, but some DVD audio tracks are specially encoded for Dolby ProLogic and ProLogic II so that you get "real" surround from only 2 channels of information. It's nothing like Dolby Digital 5.1, but it's not necessarily just creating channels out of nothing either.

[Durandal]

Now, what if we connect the sound card output into a dedicated Dolby decoder? Are those PC 3D sound standards compatible with any kind of Dolby standards?

No, it will not. I assume that you'd be using an S/PDIF output from your sound card into a receiver in this case. In your scenario, the sound card, depending on the scenario, will send one of two signals over the S/PDIF:

1. An untouched audio stream, like AC3 or DTS. This is known as pass-through.
2. A PCM stream.

In case 1, a dedicated Dolby receiver will be able to decode the signal and create the surround field properly. In case 2, the receiver will simply pass whatever channels it gets along to the speakers, which will usually mean plain old stereo sound. If you choose, you can apply certain filters like ProLogic to the stereo signal you get, but the original signal will still be two channels of information, no more.

Case 1 will generally only happen if you have DVD player software that supports sending the raw AC3 or DTS stream out through the sound card's S/PDIF port for decoding by the receiver. No games I know of create an AC3 stream for surround sound. It's possible that Doom 3 on Mac OS X will end up doing exactly that, however. But I digress.

The only way you'd be able to use a Dolby receiver to create a true surround field with a game's audio is if the game either creates an AC3 or DTS stream for its surround audio or if the audio API being used (EAX, OpenAL, whatever) creates the discrete channels of audio and then special software in your sound card's drivers encodes those channels into a 5.1 AC3 stream. Either way, it'd be a processor-intensive task, since the AC3 encoding would have to be done by the CPU. I don't think that gamer sound cards have AC3 encoders on them.

[Kreshna Aryaguna Nurzaman]

phongn and Darth Wong: Thanks for the response. The most relieving is the explanation on A3D/EAX/DS3D. First I was under the impression that "surround" sound technological development in PC had strayed quite far from their stereo counterparts. I'm glad it's not true.

Still, if you guys don't mind, I still have a lot of questions boggling in my mind (some of them are mostly to confirm, though):



1. What kind of result of passing DD-encoded signal through two-channel PCM connector (L/R), into a DD pre/pro? For example, playing DD-encoded DVD on my PC using SoundBlaster AWE 32 soundcard?

For Dolby ProLogic, there would be no problem with this setup (playing Dolby ProLogic games using two-channel output soundcards, where the two-channel output are connected to external ProLogic pre/pro), am I correct?



2. Regarding SPDIF-out on "Dolby-Capable" soundcard (never use that port), does it pass *all* sound produced by the soundcard (DirectSound, wave, MIDI, line-in, etc), or only DD-encoded signal from certain devices like DVD player?



3. Regarding to "fake" surround sound as phongn mentioned:

If your sound card is incapable of DD encoding at best you will be outputting two-channel PCM to the receiver or pre/pro. You may be able to get "faked" surround sound from that.

Well, since most soundcards today have four channel (5.1) analog outputs, are they better than two channel (L/R) output in regards to the final, "faked" surround sound produced? Or even worse?



4. Since A3D/EAX/DS3D have nothing to do in encoding the signal to DD, not to mention that no soundcard is capable to do such thing, then what method they use to distribute the signal to their 5.1 analog output?

What kind of "3D sound" we hear when combining soundcards (with 5.1 analog output, which is quite common today) with 5.1 powered (cheap) PC speakers like Altec Lansing? Some "fake" surround like Dolby ProLogic? If that's the case, will using external Dolby ProLogic pre/pro improve the "surround" quality?



Again, thanks for the response, guys. I think there's still much I have to learn before actually buying anything!

[Kreshna Aryaguna Nurzaman]

In case you guys wonder why I bothered asking all these questions, here's the backstory. A truly old geezeer in PC games, I'm still keeping old soundcards (with two channel output) like SoundBlaster 16, to play DOS games in pure DOS mode. Meanwhile, I recently played Assault Rigs, a DOS games with Dolby Surround capability. So I get the idea of connecting my PC to an external ProLogic pre/pro. Since I knew that ProLogic is capable of transmitting "surround" signal through "common" stereo channel, I see no problem of building such setup.

But then I started thinking about more modern games like WarCraft III which supported "EAX 3D Positional Audio", which I have no idea what the hell exactly it is (not to mention the likes of Aureal 3D, DirectSound, etc). I also wondered whether those "3D audio standards" will work if I'm using external Dolby processor.

[RANT]
Damn, why don't those game take simpler approach and using ProLogic, which is common audio standard, or even DD if processor permits, instead of those fancy-named things. (Though eventually phongn and DW told me that those things have nothing to do with signal distribution at all)
[/RANT]

And of course, there are things like SPDIF and soundcards that claiming to be "Dolby Digital capable". So I guess it's time for me to seek Yoda and learn more about the Force.

[Kreshna Aryaguna Nurzaman]

1. An untouched audio stream, like AC3 or DTS. This is known as pass-through.
2. A PCM stream.

In case 1, a dedicated Dolby receiver will be able to decode the signal and create the surround field properly. In case 2, the receiver will simply pass whatever channels it gets along to the speakers, which will usually mean plain old stereo sound. If you choose, you can apply certain filters like ProLogic to the stereo signal you get, but the original signal will still be two channels of information, no more.

The only way you'd be able to use a Dolby receiver to create a true surround field with a game's audio is if the game either creates an AC3 or DTS stream for its surround audio or if the audio API being used (EAX, OpenAL, whatever) creates the discrete channels of audio and then special software in your sound card's drivers encodes those channels into a 5.1 AC3 stream. Either way, it'd be a processor-intensive task, since the AC3 encoding would have to be done by the CPU. I don't think that gamer sound cards have AC3 encoders on them.

Well, in regards to the typical soundcards today (who have 5.1 analog outputs), in conjuction with A3D or such, could we say that (while playing A3D games) the output signal from the soundcard is already distributed (in front and rear channels) by such API, which is not compatible with Dolby anyway, thus connecting the output into an external DD pre/pro will actually remove the API-generated "surround" effect?

So what's the best way to connect our PC to home theater system, then?

[Kreshna Aryaguna Nurzaman]

Ergo: will we actually experience "less surround" sound effects by connecting our 5.1 analog output to an external Dolby pre/pro, compared to using 5.1 PC speakers like Altec Lansing?

[Vertigo1]

I've connected my computer to the home theater system downstairs via spidif (coaxial audio) without any problem and it played the audio properly.

What's the sound card are you using?

nVidia's SoundStorm codec

[Durandal]

Well, in regards to the typical soundcards today (who have 5.1 analog outputs), in conjuction with A3D or such, could we say that (while playing A3D games) the output signal from the soundcard is already distributed (in front and rear channels) by such API, which is not compatible with Dolby anyway, thus connecting the output into an external DD pre/pro will actually remove the API-generated "surround" effect?

When you're using the analog outputs on your soundcard, you're probably not going to have any use for a Dolby receiver because the API will have already created the surround field and sent the channels to the appropriate analog ports on the sound card, which run directly to the appropriate speakers. This of course assuming you have a set of PC speakers, where the receiver is typically integrated into the subwoofer.

So what's the best way to connect our PC to home theater system, then?

For home theatre purposes, the best way to connect your PC is with a sound card that supports S/PDIF. The idea behind a HTPC is geared toward using your PC as a super media player, and that will involve heavy use of DVDs, so S/PDIF would be the best way to go. However, if you want to watch whatever DivX/XviD/3ivx rips you have lying around, that's different. If the rip has a surround sound track (which no AVI file should ever have, period, but I digress), it must be an AC3 or DTS track first of all. Secondly, you must be playing the rip with a player that supports AC3 passthrough. I believe VLC does. Though you might get the surround field if you use a decoder capable of decoding 5.1 AC3 ... I'm not sure if all 6 PCM channels would be sent over the S/PDIF or if the receiver would run them to the appropriate channels though. That's a little bit trickier.

I know that some receivers out there also support decoding AAC audio, which supports 5.1 surround sound, but those are pretty rare, and I don't know of any players that do AAC passthrough yet, though there's a good chance that the next version of QuickTime will support it.

For gaming purposes though, you'd have to use direct analog connections to the speakers.

[andrewgpaul]

Would I be correct in saying, if your soundcard has a selection of mionijack outputs for surround-sound (mine has one for L/R front, one for L/R surround, one for centre/sub), you could connect these to separate 5.1 analogue inputs on a surround decoder with appropriate inputs, by using 3 minijack->twin RCA cables? You might have to figure out which RCA corresponds to which channel from the minijack by trial and error, but that should work, right?

Of course if your soundcard doesn't have those outputs, and your surround sound setup doesn't have the inputs (integrated DVD player/surround amps often don't), then that's of no help to you.

[Durandal]

Would I be correct in saying, if your soundcard has a selection of mionijack outputs for surround-sound (mine has one for L/R front, one for L/R surround, one for centre/sub), you could connect these to separate 5.1 analogue inputs on a surround decoder with appropriate inputs, by using 3 minijack->twin RCA cables? You might have to figure out which RCA corresponds to which channel from the minijack by trial and error, but that should work, right?

If your receiver can take RCA inputs for the front pair, rear pair and center/sub pair, yes, provided your sound card has done the decoding already and is shipping PCM streams out through the analog jack.

[The Kernel]

Would I be correct in saying, if your soundcard has a selection of mionijack outputs for surround-sound (mine has one for L/R front, one for L/R surround, one for centre/sub), you could connect these to separate 5.1 analogue inputs on a surround decoder with appropriate inputs, by using 3 minijack->twin RCA cables? You might have to figure out which RCA corresponds to which channel from the minijack by trial and error, but that should work, right?

If your receiver can take RCA inputs for the front pair, rear pair and center/sub pair, yes, provided your sound card has done the decoding already and is shipping PCM streams out through the analog jack.

Most do via the DVD-Audio/SACD analoge inputs.

I'd also like to point out that The Inq ran a story recently that Terratec is working on a card with Dolby Digital Live! (the new name for Dolby Digital Encoding in a sound card) that should be out early next year. There are also rumors that nVidia is planning a discrete SoundStorm solution for the audio add-in market.

[phongn]

1. What kind of result of passing DD-encoded signal through two-channel PCM connector (L/R), into a DD pre/pro? For example, playing DD-encoded DVD on my PC using SoundBlaster AWE 32 soundcard?

You're not sending PCM data if you're using the line-out. That's your standard analog line-level signal. If you used that you'd get stereo-out (plus any surround-sound trickery like Pro Logic if your receiver supports it).

For Dolby ProLogic, there would be no problem with this setup (playing Dolby ProLogic games using two-channel output soundcards, where the two-channel output are connected to external ProLogic pre/pro), am I correct?

'tis fine.

Regarding SPDIF-out on "Dolby-Capable" soundcard (never use that port), does it pass *all* sound produced by the soundcard (DirectSound, wave, MIDI, line-in, etc), or only DD-encoded signal from certain devices like DVD player?

It can pass all sound out through SPIDF. However, most of the time (on most sound cards) it will merely be passing 2-channel PCM. Only things like DVDs will be passing through DD/DTS sound.

Well, since most soundcards today have four channel (5.1) analog outputs, are they better than two channel (L/R) output in regards to the final, "faked" surround sound produced? Or even worse?

Better in every way.

Since A3D/EAX/DS3D have nothing to do in encoding the signal to DD, not to mention that no soundcard is capable to do such thing, then what method they use to distribute the signal to their 5.1 analog output?

You're still a bit confused. Dolby Digital is like MP3 -- it is a sound standard (specifically using AC3 compression). What things like nVidia's SoundStorm do is take 5.1-7.1 discrete channels of information and encode it into a Dolby Digital stream. You could liken it to compressing MP3s on-the-fly.

For cards that don't do DD encoding, they simply output each channel seperately rather than compressing and "bundling" the audio.

What kind of "3D sound" we hear when combining soundcards (with 5.1 analog output, which is quite common today) with 5.1 powered (cheap) PC speakers like Altec Lansing? Some "fake" surround like Dolby ProLogic? If that's the case, will using external Dolby ProLogic pre/pro improve the "surround" quality?

That's true surround sound. Many DVD player programs decode Dolby Digital and decompress and "unbundle" the audio and send them to their proper channels. Similarly, a game designed for multi-channel output will instruct the sound card to set each sound where.

What's missing is the ability to encode all those channels into a single digital datastream (like DD).

[RANT]
Damn, why don't those game take simpler approach and using ProLogic, which is common audio standard, or even DD if processor permits, instead of those fancy-named things. (Though eventually phongn and DW told me that those things have nothing to do with signal distribution at all)
[/RANT]

Realtime Dolby Digital encoding is bandwidth and processor-intensive. Furthermore it is useless for actually calculating where the sound goes to -- that's the job of EAX/A3D/DS3D. Those things figure out what channel(s) to send the sound, DD/DTS are mostly used as transport layers. ProLogic is something of a kludge (abliet a mathematically sophisticated one) that is no longer neccessary.

I'd also like to point out that The Inq ran a story recently that Terratec is working on a card with Dolby Digital Live! (the new name for Dolby Digital Encoding in a sound card) that should be out early next year. There are also rumors that nVidia is planning a discrete SoundStorm solution for the audio add-in market.

The advent of PCI-E is apparently what made it feasable to do it -- IIRC, PCI 32/33 didn't have enough bandwidth, forcing nVidia to integrate it on the chipset for the nForce2. If the Inq's report about Terratec is true that's good news -- they make quality stuff.

[Kreshna Aryaguna Nurzaman]

I've connected my computer to the home theater system downstairs via spidif (coaxial audio) without any problem and it played the audio properly.

What's the sound card are you using?

nVidia's SoundStorm codec

You lucky bastard.

[Kreshna Aryaguna Nurzaman]

Would I be correct in saying, if your soundcard has a selection of mionijack outputs for surround-sound (mine has one for L/R front, one for L/R surround, one for centre/sub), you could connect these to separate 5.1 analogue inputs on a surround decoder with appropriate inputs, by using 3 minijack->twin RCA cables? You might have to figure out which RCA corresponds to which channel from the minijack by trial and error, but that should work, right?

If your receiver can take RCA inputs for the front pair, rear pair and center/sub pair, yes, provided your sound card has done the decoding already and is shipping PCM streams out through the analog jack.

No, wait. You said for gaming purpose, I'd better use direct analog connection to speaker, because the signal is already distributed for each analog output by the soundcard itself, right?

Or maybe I'm confused between surround decoders and surround receivers.


When connecting 5.1 analog outputs from a soundcard, into 5.1 analog inputs on the back of a surround receiver/decoder, I always thought one of the several possible scenarios below:


1. The surround receiver/decoder will decode the signal using certain standard (Dolby, dts, etc), provided that computer 3D sound like EAX/A3D/DS3D is compatible with mainstream Dolby or dts . Now, I already knew that this is wrong. In fact, this is my early misconceptions on surround sound.


2. The surround receiver/decoder will *preserve* the channel separation, keeping the surround distribution has been performed by the soundcards. In this case, the surround receiver/decoder acts nothing more than receiver, and the surround output has nothing to do with DD, dts, or any standard the receiver is capable to decode. This



3. The surround receiver/decoder will *preserve* the channel separation, keeping the surround distribution has been performed by the soundcards, but the receiver/decoder *does* enhance the surround sound resulted from the soundcard. For example, if the soundcard's output is 5.1, but the receiver/decoder's output is 7.1, then the receiver will enhance the surround into 7.1 (by providing "fake" surround, etc) using certain algorithm like Dolby ProLogic.



4. The surround receiver/decoder will *not* preserve the channel separation. It will have the already separated channel inputs mixed up together, then it will separate the channel again to its output using "fake" surround algorithm like ProLogic. So by using the surround receiver, the final surround sound we hear may be actually "less surround" than if we connect the soundcard directly to computer speakers like Altec Lansing.



I already knew that number 1 is inccorrect (my early misconception on surround sound). Number 2 is what I've been thinking as other possibilites alongside number 1, and which I believe more by reading the posts here. Number 3 is what I'm hoping for, while number 4 is what I've been afraid of (because I'm always into the idea of integrating PC sounds with "mainstream" stereo system, and I actually
*hate* el-cheapo, powered PC speakers).

So, guys, from all possible scenarios I've been thinking of above (save number 1, which is actually wrong), which one is most possible? Which one is least possible?

Thanks,

[phongn]

Either 2 or 3 will be correct depending on your setup.

[Kreshna Aryaguna Nurzaman]

Either 2 or 3 will be correct depending on your setup.

How to achieve number 3, then? Is having a 7.1 surround receiver can really "enhance" 5.1 surround from games?