SPDIF Confusion/Question

[RatBastrd]

This SPDIF stuff that are now coming on the newer mobos(I will be getting the IC7 Max3 if it ever shows up in stores)... Is this the same as the Optical cable that you use when dealing with your home theatre setup? I mastered that just fine... Home Theatre sounds great.

Now I wanna do the same with my PC. Would it work the same... Connect the SPDIF(Optical) Out to a receiver and then from there to the speakers?

Is it worth it at all, or are there very few games that do the 5.1 or any type of surround?

Thanks.
Rat.

 

[Tab]

I also have another question relating SP/DIF. Does it make that much of a difference? I've also heard Optical isnt really that great. Anyone have any speaker suggestions besides the Klipsch, Logitech, Creative? I've seen the Creative 5.1 MegaWorks reatively cheap.

 

[joeld]

Originally posted by: RatBastrd
Is it worth it at all, or are there very few games that do the 5.1 or any type of surround?

as far as I know nForce's onboard audio will encode into DD5.1, so even if you play games or stuff that doesn't do dolby, the soundstorm will encode it in that and transmit across spdif. It has options for dolby surround, 5.1, and mixers for all the channels to output. I've never used it myself (our home theater equipment is 20 years old - no SPDIF ), and you may not consider an nforce based mobo, but its an option at least.

 

[RatBastrd]

Originally posted by: joeld

Originally posted by: RatBastrd
Is it worth it at all, or are there very few games that do the 5.1 or any type of surround?

as far as I know nForce's onboard audio will encode into DD5.1, so even if you play games or stuff that doesn't do dolby, the soundstorm will encode it in that and transmit across spdif. It has options for dolby surround, 5.1, and mixers for all the channels to output. I've never used it myself (our home theater equipment is 20 years old - no SPDIF ), and you may not consider an nforce based mobo, but its an option at least.

Thanks for the response joeld. I appreciate it.

I am considering anything that is faster than my current setup. I have no loyalty to Intel or AMD, but I have read that the current P4's are very OC-able.

So, NForce2 if I decide to go with AMD... Anything similar for the Intel platform?

 

[kylef]

I think there are very few games that actually do Dolby Digital 5.1 sound effects. Most of the SPDIF folks use it for Dolby Digital AC-3 pass-thru when playing DVD movies on their computers. Then you're just dumping the Dolby Digital 5.1 bitstream out from your sound card's SPDIF out to your receiver, and your receiver does the Dolby Digital decoding.

I, on the other hand, am one of the few users who use SPDIF to play normal stereo sound because I can't stand the crappy digital to analog converters present in most onboard sound cards/solutions. Using SPDIF out to a receiver uses the receiver's DAC, producing in most cases superior sound quality.

[edit]
Oh, and I forgot to mention that SPDIF can mean either optical or coaxial. SPDIF just refers to the digital bitstream standard; the actual physical layer that connects the two devices can be electric (coaxial) or optical (TOSlink). Coaxial tends to be cheaper because you can use any cable with the right impedance, and in some cases you don't even need to worry about the impedance (you can usually get away with an el-cheapo RCA to RCA mono cable). TOSlink fiber cables, on the other hand, are usually $10 to $15 for 6 feet at a major B&M store.

 

[NicColt]

well said kylef. To put it in simple terms it is imposible for an spdif/out to carry an annalog 5.1 signal through the coax or optical fiber, so anything that is played analog will default to a 2 channel stream. It will go through the onboard codec and/or soundstorm for example to 'simulate' surround on a 2 channel stream. The only way you can get 'real' 5.1 6.1 or 7.1 surround with coax or optical fiber is to play a digital souce like AC3/DTS or DD which is what is on DVD's for example. Even though spdif/out, coax out and optical fiber out looks good it does have limitations when it comes to playing analog sources.

Here's two examples for the best of both worlds. If you take the Logitech's Z680's for example, you can connect both the optical and the digital din's and when you play DVD's select the coax/optical out to get the most out of the DTS or DD. and when you decide to play games or analog sources select the digital din's to get the full EAX 5.1 surround.

The other example is the Audigy2 with the Megaworks all you need to do is to connect the 1 cable digital din and that's it. For DVD's it uses a lossless compression to give full Dolby Digital EX surround in 24-bit/96kHz in 5.1 and for games the Audigy2 is the only one that can do 6.1 surround with 24 bit EAX.

Sudhian has a good article that puts a little light on the subject.

 

[Tab]

I am so lost....

You guys make SP/DIF sound like absolute crap. Let say I get some Klipsch ProMedia 5.1s. How would you get the best sound, wouldn't you want to SPDIF?

 

[NicColt]

>How would you get the best sound, wouldn't you want to SPDIF?

from what I know now, If games are your main play I'd go digital din and not spdif. There's no problem in playing movies in DD it's just a little tighter compression, if I can use that term. DD is I think 10:1 compression and DTS is something like 4:1 but again the best would be if you have an Audigy2 which doesn't compress the signal and even if you have your Klipsch connected through digital din which would be better. IMO

>You guys make SP/DIF sound like absolute crap.

It's not that it's crap.... It's just that it has limitations when using the same computer system to play digital and analog feeds. It's just that sound cards and speaker systems don't implement it very well. Like I said the Z680's do a good job at switching from DTS/AC3 digital to Analog feeds, but Creative decided to take a whole new approach that is better in my opinion in offering uncompressed DVD sound in Dolby Digital Pro Logic II while at the same time offering full game support with the same connections, which is better in my opinion.

Games are EAX and DVD's are THX/DTS/AC3 and that's not going to change anytime soon. We just need to see who implements all of this better in the long run and right now Creative has a leg up.

 

[kylef]

as far as I know nForce's onboard audio will encode into DD5.1, so even if you play games or stuff that doesn't do dolby, the soundstorm will encode it in that and transmit across spdif.

I missed this when I replied earlier, my apologies. I actually had never heard of this feature, so I looked it up briefly. It does appear that nVidia's Soundstorm technology (whether it's implemented as a software driver or real hardware, I don't know) will actually take the 4- and 5-channel analog audio from games (or any other source, presumably) and literally encode these channels into a true Dolby Digital 5.1 bitstream, which can then be sent over SPDIF out to your receiver.

This is in fact one of the cooler things I have read about in a while. This would allow you to make the ONLY connection between your computer and your stereo equipment a single SPDIF cable (such as TOSlink). With this single cable, you could send normal stereo PCM bitstreams to your receiver for decoding, as well as true Dolby Digital 5.1 bitstreams for surround sound, and the surround sound would work for both DVDs and games.

Tabb, regarding your question about Klipsch speakers and SPDIF:

The reason you might not want to get those speakers for gaming is that the ONLY way to get surround sound using the Promedias is to send them a Dolby Digital 5.1 signal over the SPDIF connection. As I said earlier, most sounds cards (like the Audigy2) do not have the functionality that I was just describing (Nvidia's "Soundstorm"), and therefore most games you play will NOT be in surround sound (since they don't natively support DD5.1 output). Games written specifically for game consoles like the Ps2 and XBox, on the other hand, specifically use DD 5.1 encoded sound effects, so those speakers would be great for that application (hooking them up directly to an XBox using SPDIF). Those speakers would also apparently work well if you had that Nvidia Soundstorm chipset on your mobo, which will "encode" your games' analog surround sound into a true DD 5.1 bitstream. And they would also work if you just play DVDs and don't do games.

Does that make more sense?

 

[Dug]

There's no problem in playing movies in DD it's just a little tighter compression, if I can use that term. DD is I think 10:1 compression and DTS is something like 4:1 but again the best would be if you have an Audigy2 which doesn't compress the signal and even if you have your Klipsch connected through digital din which would be better. IMO

WTH are you talking about?
The DD signal is already compressed and is just passed through. The Audigy2 has nothing to do with it and doesn't improve the signal or pass it with less compression.

#2 The DD encoding done on the NForce2 is just that. It creates a DD signal from 2channels in hardware, exactely like the Xbox (which is an Nvidia board.) That way you get 5.1 sound over an SPDIF connection. It does this very well btw and prefer it to any EAX solution.

Games are EAX and DVD's are THX/DTS/AC3 and that's not going to change anytime soon. We just need to see who implements all of this better in the long run and right now Creative has a leg up.

Nvidia has the leg up because its the only way to encode DD. Creative can not do this. Creative does do EAX better than the Nforce, if this is what you prefer.

RatBastrd- The Intel motherboards can only pass DD content and can't encode DD, big difference from the Nforce. So you can't get 5.1 sound from games on the Intel board, just movies.

 

[RatBastrd]

I was leaning towards the IC7-G Max3 mobo(Intel) or an unknown(prolly ABIT) Nforce2 mobo(AMD)...

I think the confusion is this thread is another reason for my, and others, confusion... There just seems to be alot of people talking and, while I appreciate the help, I hope this thread will help someone in the future as I am sure it will come up again.

Again, thanks to all that offered info!

 

[kylef]

I think the confusion is this thread is another reason for my, and others, confusion...

What confusion, darnit? Just read *my* posts and you won't be confused!

Just kidding...

 

[Dug]

I'm not just talking, I know.

I have both an Epox Nforce2 and Abit IC7 mb setup and have an extensive Home Theater setup.
I have tried just about every configuration available to check sound and performance.

Each situation is different, but if you want DD 5.1 gaming with every game, then the Nforce2 is your only option.
If you just care about 5.1 for movies, then anything with digital out will work fine when plugged into your receiver.
If you want the best EAX sound get an Audigy2. (This won't work over an SPDIF connection though)
If you want the best 5.1 performance for movies, then get an M-Audio Revolution and use the analog outs to your receiver. (The DAC's on the Revolution are better than most receivers costing up to $1000)

 

[RatBastrd]

Originally posted by: Dug
I'm not just talking, I know.

I have both an Epox Nforce2 and Abit IC7 mb setup and have an extensive Home Theater setup.
I have tried just about every configuration available to check sound and performance.

Each situation is different, but if you want DD 5.1 gaming with every game, then the Nforce2 is your only option.
If you just care about 5.1 for movies, then anything with digital out will work fine when plugged into your receiver.
If you want the best EAX sound get an Audigy2. (This won't work over an SPDIF connection though)
If you want the best 5.1 performance for movies, then get an M-Audio Revolution and use the analog outs to your receiver. (The DAC's on the Revolution are better than most receivers costing up to $1000)

Thanks alot..

Will the Nforce2 do EVERYTHING(movies, games and EAX) in 5.1? Basically, will it make everything I select turn into a 5.1 stream from my Nforce2 board, to my receiver? Maybe not EAX, right?

 

[Tab]

What is Digital DIN?

Will soundcard manufactures benifit from PCI-Express?

Lets say you get your Audigy 2 and Klipsch/Logitech/Creative $350 Speakers. What would be the best configuration to use? For Games,Music and DVDs.

 

[Dug]

Will the Nforce2 do EVERYTHING(movies, games and EAX) in 5.1? Basically, will it make everything I select turn into a 5.1 stream from my Nforce2 board, to my receiver? Maybe not EAX, right?

It will do movies and games, but not EAX over spdif. In the game you don't select any 3d sound so the stereo 2 channel is encoded into 5.1. Movies are just passed through the spdif out and is decoded by your receiver.

 

[NicColt]

>Does that make more sense?
>a Dolby Digital 5.1 signal over the SPDIF connection.

Well we have to be carefull as to the meaning of DD 5.1 over a spdif connection. You cannot send a TRUE Dolby Digital 5.1 over an spdif connection..... I ask anyone to show me documentation that says that a coax/spdif/optical connection can send a true dolby digital feed. What soundstorm and others do is send what should be called a Virtual or Simulated DD signal on two channels it does not send a dedicated 5 channel Dolby Digital feed.

>What is Digital DIN?

it's a cable that can carry Analog and Digital feeds whereas a coax/spdif/optical cable can carry only a digital connection. Therefore when sending an analog connection over an coax/spdif/optical cable it will default to a two stream feed. An RCA cable will carry it own dedicated stream.

>The Audigy2 has nothing to do with it and doesn't improve the signal or pass it with less compression.

Yeap my bad, I was thinking about something else.....

>What would be the best configuration to use? For Games,Music and DVDs.

If you want the best compatible for all three, I would say this..... (and within common sense because there is no limit) If you have an Audigy2 or thinking of getting an Audigy2 then get the Soundworks 550 or 650 and connect it with the digital din then you will get full 5.1 or 6.1 with whatever you are doing. If you have another soundcard or using onboard sound then get the Z680's and connect both the spdif out and the digital din and the 680's will switch between Digital and Analog.

 

[Dug]

Well we have to be carefull as to the meaning of DD 5.1 over a spdif connection. You cannot send a TRUE Dolby Digital 5.1 over an spdif connection..... I ask anyone to show me documentation that says that a coax/spdif/optical connection can send a true dolby digital feed. What soundstorm and others do is send what should be called a Virtual or Simulated DD signal on two channels it does not send a dedicated 5 channel Dolby Digital feed.

I think your thinking of Prologic signals. A true DD 5.1 signal is just that from the encoding to decoding process. It is discrete. Go to Dolby's site and read up on it.

From Dolby : "Dolby Digital 5.1 is a discrete system that keeps the multiple channels fully separated throughout the encoding and decoding processes"

"Dolby Surround is a matrix encoding process that in essence ?folds? Left, Center, Right, and Surround channels onto stereo soundtracks. A Pro Logic decoder ?unfolds? the four channels on playback (without a Pro Logic decoder, the encoded program plays in regular stereo)."

And the Nforce does send a dedicated 5.1 signal otherwise I wouldn't see the DD light on my receiver come on.

 

[kylef]

You cannot send a TRUE Dolby Digital 5.1 over an spdif connection..... I ask anyone to show me documentation that says that a coax/spdif/optical connection can send a true dolby digital feed.

Uh... I have a TOSlink cable going from the SPDIF/out on my Hercules Gametheater XP directly into my Pioneer receiver, and I watch Dolby Digital 5.1 movies in this manner. It's called AC-3 passthrough.

Dolby Ac-3 Encoding, for DD 5.1

And here's a link from MSDN describing how AC-3 (Dolby Digital 5.1) over S/PDIF actually works:
AC-3 over S/PDIF

 

[NicColt]

>It's called AC-3 passthrough.

Of course you are correct. If the source, the codec and the player are digital of course you will have DD5.1 but I think after reading my own post I didn't write it correctly.

I was refering to this line.

>Nforce2 do EVERYTHING(movies, games and EAX) in 5.1? Basically, will it make everything I select turn into a 5.1 stream from my Nforce2 board, to my receiver?

When saying "You cannot send a TRUE Dolby Digital 5.1 over an spdif connection....." I meant that if you watch a DD 5.1 movie for example with winamp which is not AC-3 capable it will be analog and in turn send the signal back through the TOSlink cable but there is no way that you will have a TRUE Dolby Digital 5.1 signal once converted to analog. Therefore when I said "What soundstorm and others do is send what should be called a Virtual or Simulated DD signal on two channels it does not send a dedicated 5 channel Dolby Digital feed."

If the source codec and player are digital then your fine, but the moment it's converted to analog from the onboard sound chip/codec, Soundstorm or Vinyl Audio for example will do it's best to re-encoded back into a virtual surround and send that feed it back to the digital cable.

This is why with the Z680's when the Feed is digital it will play through the digital/optical and if the Feed is analog it will play through the digital/din. which is the best of both worlds. In my opinion I would still go with the CL MegaWorks 550 or 650.

 

[Cheep]

Ok, here's a question along these lines. nForce 2 passes DD 5.1 through the SPDF out, whether it's games, movies, etc. The question is, though, if I watch a DVD movie, how do I get the digital audio to the mobo, in order to connect the SPDF out to my receiver? Do you have to connect the SPDF-out from the DVD player to the mobo? Or is that information just transmited along the IDE cable to the mobo, the same as the picture?

I ask because some mobos don't have a SPDF-in for the DVD-ROM. In that case, how do you get DD 5.1?

 

[NicColt]

I'm retired from the spdif debate : )