Digital Audio + Consoles

[Logistics]

Most people on these forums seem more interested in the converting to RGB for use on TV's, Monitors or what-have-you to get the highest quality picture, but I don't see alot of audio guys around.  Maybe because most people here goof with classic consoles that aren't known for their digital audio because there was no provision for it implemented in the A/V connectors... and yet people are implementing RGB conversions.  ?!

Anyway, I was looking at the schematics for the PSX(the original playstations) because someone mentioned adding SPDIF to them and that peaked my interest.  However, then I saw it... the PSX's Audio processor supports I2S.  If you don't know what this is, it is essentially the RGB of the Audio world, because rather than mixing Clock Signals with Data Signals over SPDIF, it seperates the data and even the clock signals from eachother.


Edit:  Actually, I'm assuming it supports I2S.  As is mentioned in many articles, I2S has no predominant standard in it's usage.  Sometimes you see pinouts referring to Bit Clock and Word Clock with the Data line, whereas people like Creative Labs have Sdata, LRCLK and BCLK.  IC732 which is the PSX sound processor has two sets of pins which look like they would be the I2S output.  On the side of the processor which has the outputs for Analog Audio(Left and Right) you also have pins 155, 156 and 157, being DAT0, LRC0 and BCK0 respectively.  DAT0 is not used here, whereas LRC0 and BCK0 lead to somewhere, but I can't for the life of me tell where using this PDF.  Since they have arrows indicating these signals are outgoing, I am guessing these are used in connection with the CD mechanism, perhaps some sort of timing stuff.  However, on the other side of the IC altogether we have pins 14, 15 and 16, being DOUT, LRCK and WDCK respectively.  Again DOUT leads nowhere, but LRCK and WDCK are traced, but also appear to lead nowhere... perhaps ground or bypass capacitors which lead to ground.


Now, I don't know of any reciever or amplifier of any kind that has I2S hookups on it.  I read that there are problems if you have to extend the signals over any sort of distance since it would require amplification which appears tricky with I2S.  However, while researching stuff about SPDIF, I found that Sound Blaster Live!'s, even the older ones, including value models, have a slew of digital ins and outs that Creative Labs doesn't tell you about and even lists as "Not Connected" on their datasheets, but are very simple to enable.  The same cards also have I2S inputs and outputs which, again they don't tell you about.  Even Creative's DXR3 DVD Decoder cards support I2S.  Perhaps there is some potential for wiring up some sweet digital action between consoles and soundcards, especially multi-channel cards for excellent surround...

Which brings me to developers.  I don't know off hand of any PSX games which are widely reveared for their insanely hi-fi sounds or audio recordings... but then I bought a PSX years after they were out and the only couple games I've ever played on a PSX was NFS3HP and Crash Bandicoot.  lol!  With only your typical L/R RCA audio cables, there's not a huge potential for high quality surround from a PSX, but it makes me wonder if game developers ever had this in mind and developed their software with high end capabilities, just in case.  Perhaps with an implementation of SPDIF or I2S we would find that some old game did in fact have some sort of crazy surround action going on.

Anyway, I admit I'm one of those guys who always tends to learn just enough about something to be dangerous so this could all be a big mish-mash of useless jibba-jabba.  Please pity me if I is a foo'!  


p.s.  Lawrence, hurry it up with those SPDIF mods, would you?  

[atom]

NFS HP was a game ahead of its time in sound effects. Really it was!

[viletim!]

Logistics,
Do you really think the DAC in you receiver (or whatever) is noticably better than the one in your playstation?

[kendrick]

Just as most people don't have RGB-capable monitors, I would wager that most people don't have digital audio equipment in their house. Even among us hardcore gamers, there's just no benefit to the audio mods being described here if we don't have the gear to appreciate it. I dare say that the benefit of enhanced, uncompromised audio is less evident than than of enhanced, uncompromised video even to the discerning ears and eyes.

-KKC, studiously ignoring the Super Bowl.

[Hojo_Norem]

Just as most people don't have RGB-capable monitors, I would wager that most people don't have digital audio equipment in their house. Even among us hardcore gamers, there's just no benefit to the audio mods being described here if we don't have the gear to appreciate it. I dare say that the benefit of enhanced, uncompromised audio is less evident than than of enhanced, uncompromised video even to the discerning ears and eyes.

Unlike RGB capable monitors Digital AV equipment is making its way into more homes all the time, either in the from of DVD surround kits or AV Surround Receiver amps which are more than capable of handling digital audio.  I should know, I sell them among other AV related things.

As for the difference.  50/60Hz hum says it all.  My SNES is crystal clear with the SPDif mod but before the hum was irritating at times.  More so for the Gamecube.  The real benefit of digital audio is most apparent if you like playing games with the volume cranked pretty high.  Again with my SNES I couldent do this before the mod because the background hum was there all the time.  Post mod now I only here sound from my speakers when Im suppost to.  (Starwing just sounds awsome with the volume up high!)

[Drewman21]

Unless I missed it. Is it possible to use the normal stereo out anymore on a SNES after doing the SPDif mod?  I have never been to diehard about my sound setup until recently but i'm starting to finally get the components together for a decent theater system.
So Butter_pat where do you work at?

Drewman21

[Hojo_Norem]

If I understand the mod correctly the analouge audio out should still work fine.

As for my place of work....I work in a TV shop selling most things related to TV and Audio, with a few washing machines on the side.  The thigs we sell the most of recently are Panasonic LCD, scart leads and Freeview digiboxes (only the devil himself could come up with those...)

[Logistics]

Logistics,
Do you really think the DAC in you receiver (or whatever) is noticably better than the one in your playstation?

My intention was to point out that the PSX appears to have provision for something even better than SPDIF, that being an I2S interface.

First you have your Transport, such as a CD Player, which sends a Data Signal and a Clock signal to, typically an SPDIF Transmitter which combines Data and Clock signals(not-as-good) and then sends it to an SPDIF Reciever, which then seperates the signals again and sends them to a DAC.

However, more ideal would be for the Transport to send the data and clock signals to an I2S Transmitter which forwards the Data Signal by itself, also seperating the clock signal into individual Word and Bit clock signals and forwarding them to to an I2S Reciever, which would again combine the clock signals and forward the still seperate Data and Clock signal to a DAC

So the point is not which DAC is better, it's preserving the signal as best as possible before it is converted.  It seems logical to conclude that this would be the MOST benefical when used with a multi-channel audio setup(crazy surround, what are we up to now, 9.1?) since all channels could potentially be preserved with no intermingling.

[NFG]

Logistics: I'm going to have to question your logic here.  Combining a digital signal typically does not involve a loss of signal quality like combining an analogue video signal will.  

[Logistics]

Many a forum have had that exact comment come up Lawrence.  It's sort of a mixed bag.  It seems logical to conclude that because it is all digital data, ones and zeroes, that this sort of thing should not be a problem, but there always seem to be returning comments about how in actual practice it really does seem to make a difference.

Most of the trouble seems to be coming from the ability to feed things like SPDIF over long distances.  TOSLINK seems at one end to be the best because there is no electrical connection between the source unit and destination unit, but on the other hand TOSLINK is said to be the most susceptible to jitter in comparison to AES/EBU, SPDIF and I2S.  The problem does not seem to be that the Data gets jacked up, but rather the clock signals degrade causing jitter, which screws up the playback... which always seem to be a result of trying to run the signal over any form of cable from one unit to the next, which is said to expose the signals to interference as well.

[NFG]

It would seem that someone's confusing the issue.  Once a signal's digitized, the components of it will not and cannot degrade independantly.  All the bits will suffer the same, if there's a transient problem it will affect whatever bit happens to be in the pipe at the time.

If there's a problem mixing these signals then the problem lies not with the mixing itself, but:
with the mixing algorithm, or
with the compression used, or
in the hardware that did the mixing, or
etc.

'jitter' is a problem that arises during the data read from a CD, once it's digitized there's no such thing as jitter.  Any problem affecting a digital signal is a result of bad hardware or bad software, the signal itself is not going to change.  Indeed, it cannot.

[Logistics]

Actually, it doesn't have anything to do specifically with CD's, but simply digital data and predominantly during D/A or A/D conversion.  Again, the data signal is not the problem, but rather the clock signals.  I2S and SPDIF as well as AES/EBU are all prone to the same problem, the clock signals getting messed up for one reason or another.  I2S is only less susceptible because it never attempts to mix Data with Clock signals.

Here's a good article on the subject:  http://www.tnt-audio.com/clinica/diginterf1_e.html

See what you think.

[kendrick]

That explanation makes sense to me. Given that game sound in particular is event-driven, it's necessary for it to be moving air at the intended time (rather than being turned into sound whenever the D/A convertor feels like finishing the math.) This is the same kind of clock problem that Voice over IP carriers have to deal with, right? After a point, being on time is more important than being accurate, and so you end up having to compromise the sound by way of a mathematical approximation. That's not data loss as we would understand it for an analog signal, but it would occur every time one component has to 'catch up' to another.

This makes my head hurt. Forget speakers and wires, bring on the cybernetic audio implants.

-KKC, who's having a bad hair day.

[NFG]

It kind of proves my point though - mixing the clock with the data isn't inherently bad if you've got the bandwidth and hardware to support it.  If you run out of either CPU time or bandwidth for the signal then, duh, it's going to cause trouble.  It still doesn't have anything to with the clock signal per se.

[Vertigo]

Just as most people don't have RGB-capable monitors, I would wager that most people don't have digital audio equipment in their house.

Just so you know, we are not all Americans.
There's a great many Europeans on this board. In Europe, TVs come with SCART as standard. It's more likely than not that a European TV is RGB-capable. Try to bear that in mind.

As for the digital audio out thing, who gives a shit? The difference in audio quality is just about nothing unless you're going at it with waveform analysers and a depth of nerd that's even a bit too much for this forum, whereas the difference between composite and RGB video is immense. Even my girlfriend can tell when she's accidentally viewing composite.

[kendrick]

Just as most people don't have RGB-capable monitors, I would wager that most people don't have digital audio equipment in their house.

Just so you know, we are not all Americans.
There's a great many Europeans on this board. In Europe, TVs come with SCART as standard.

Point well taken. I guess the limitation then is more on the output capability of the console in question, rather than on what the display can do.

This gets me thinking... Here in the States, the resistance to providing or to accepting RGB as a signal type in any video equipment comes largely from economic considerations. The strongest objection comes from motion picture licensors, who don't want any method that doesn't account for Macrovision or other DRM encoding. This is why the majority of American televisions support component video input but not RGB input. Is this less of an issue in the Union, and is that because you Europeans have more sense or less lawyers? :)

-KKC, who covets small European cars.

[Vertigo]

The reason is because SCART is a French invention and so it's easier to produce a 'Europe version' TV set than to only add them for certain markets.
A lot of TVs that don't have SCART sockets actually do have a blank rectangle on the back panel and if you take the back off and look at the board you can see the pin inputs for a SCART socket. It shouldn't be all that hard to obtain a SCART parts set from somewhere like Maplin and fit your own.

[Logistics]

Just as most people don't have RGB-capable monitors, I would wager that most people don't have digital audio equipment in their house.

As for the digital audio out thing, who gives a shit? The difference in audio quality is just about nothing unless you're going at it with waveform analysers and a depth of nerd that's even a bit too much for this forum, whereas the difference between composite and RGB video is immense. Even my girlfriend can tell when she's accidentally viewing composite.

It's already been stated on this board that the digital output of some consoles proved beneficial because their analog output introduced noise/distortion into the audio lines, whereas with a digital out and an external DAC this was removed.  This also eliminates the use of the consoles onboard analog hardware, which is often garbage and could potentially block frequencies which may have otherwise existed or exaggerate others.

Also, the human ear has been proven to be an amazing tool, able to hear even the slightest differences in sound, which is why jitter in digital audio has audible effects.  As for the digital audio out thing, LOTS of people care!

[mr. newbie]

well star ocean 2 has a surround sound option. i find that interesting because i didn't know the psx could do surround.

[Hojo_Norem]

well star ocean 2 has a surround sound option. i find that interesting because i didn't know the psx could do surround.

Any machine which is capable of outputting digitally sampled sound in stereo can be made to do surround sound, its all about pre prepairing the sound samples or using on board hardware trickery to do it.  

[Logistics]

well star ocean 2 has a surround sound option. i find that interesting because i didn't know the psx could do surround.

Any machine which is capable of outputting digitally sampled sound in stereo can be made to do surround sound, its all about pre prepairing the sound samples or using on board hardware trickery to do it.

I think his point was that he doesn't remember any Playstation having a provision to output digital sound.  I don't remember ever seeing one that could either.  The Playstation does of course have an onboard Digital Sound Processor, but it is promptly converted to analog before it makes it's way through the A/V cable.  In order to output a digital signal the unit would have to be modified by wiring up a new jack or replacing something on the A/V cable.

[Drewman21]

Could you just play the game in a PS2 and use the optical out to get the sound digital?  Was Star Ocean 2 released late in the PSX's life cycle that the PS2 was on the way so they added or included the feature to work with a PS2?  Just a thought. Would be cool to see if it works.

Drewman21

[Hojo_Norem]

I think I botched my explanation a little so I'l further elaborate.

There are two types of surround sound, discrete and matrixed.  Discrete surround comes in the form of separated signals (one connection for each channel) or encoded as a digital stream, (Dolby Digital and DTS).  With discrete surround it is possible to have completely different sounds emanating from all your speakers.

Matrixed surround essentially fiddles with the phase of the rear channels before mixing it with the front channels into a single stereo signal.  Anything which outputs some form of pre-recorded stereo sound can use matrixed surround sound.  Some consoles have the ability to fiddle with the phase of their individual sound channels to achive the same effect.  I know the SNES is supposedly able to and woulden't be supprised if the PSX could also.  The main drawback from matrixed surround is that it is impossible to output two diferent sounds without sound being emitted on the other channels.

Could you just play the game in a PS2 and use the optical out to get the sound digital? Was Star Ocean 2 released late in the PSX's life cycle that the PS2 was on the way so they added or included the feature to work with a PS2? Just a thought. Would be cool to see if it works.

Drewman21

Yes you can get digital sound from PS1 games this way, but it will be matrixed surround.  AFAIK  the PS2 is only capable of outputting DD or DTS surround from pre-recorded FMV, in fact I think that the only reason the PS2 has a optical port is that it can play DVD movies... and what use is a DVD player with no digital out?

[Logistics]

"the PS2 has a optical port"  "what use is a DVD player with no digital out?"

What?

[Midori]

A DVD without digital output is still useful, unless you want digtal sound that is :-). I personaly am quite fond of my normal boring analog stereo sound so I am hardly using my digital audio option from my DVDs.(heresy!)

[Hojo_Norem]

"the PS2 has a optical port"  "what use is a DVD player with no digital out?"

What?

Not much if you want digital sound from it, considering the title of the thread.

I just hope the Revolution has some form of a proper digital audio output and not the aborted attempt that the Gamecube has.