Mixing S/PDIF

[Rein]

Hi Folks,

I hope there some audio pro's out there as the group suggests... I
have 8 pc's with sound cards possessing S/PDIF outputs that I would
like to mix down to either traditional stereo or even surround if not
price prohitive.

Any suggestions on gear thats up to the task?

Rein

[Pooh Bear]

Rein wrote:

> Hi Folks,
>
> I hope there some audio pro's out there as the group suggests... I
> have 8 pc's with sound cards possessing S/PDIF outputs that I would
> like to mix down to either traditional stereo or even surround if not
> price prohitive.

There's a fundamental problem with what you want to do, if as I suspect,
you want to mix digitally.

All digital audio mixing requires the sources to be 'in sync' requiring
the use of a master clock generator somewhere. Computer soundcards mostly
don't have any such ability, only high end stuff doing so.

> Any suggestions on gear thats up to the task?

You're stuck with an analogue mixer.

Why do you want to mix 8 PCs together btw ?


Graham

[Pooh Bear]

Another Mike wrote:

> Pooh Bear > wrote in
> :
>
> > Rein wrote:
> >
> >> Hi Folks,
> >>
> >> I hope there some audio pro's out there as the group suggests... I
> >> have 8 pc's with sound cards possessing S/PDIF outputs that I would
> >> like to mix down to either traditional stereo or even surround if not
> >> price prohitive.
> >
> > There's a fundamental problem with what you want to do, if as I suspect,
> > you want to mix digitally.
> >
> > All digital audio mixing requires the sources to be 'in sync' requiring
> > the use of a master clock generator somewhere. Computer soundcards mostly
> > don't have any such ability, only high end stuff doing so.
> >
> >> Any suggestions on gear thats up to the task?
> >
> > You're stuck with an analogue mixer.
> >
> > Why do you want to mix 8 PCs together btw ?
> >
> >
> > Graham
>
>
> What about daisy chaining all of them together via spdif and synching each
> one to the previous. This is assuming the cards can monitor the spdif input
> on the sodif output, which most can I believe.

SPDIF only carries 2 channels of audio. That's your lot. It wasn't designed as
a digital routing system, just a low cost link between hi-fi separates.

Graham

[Mike Rivers]

Rein wrote:

Hi Folks,

I hope there some audio pro's out there as the group suggests... I
have 8 pc's with sound cards possessing S/PDIF outputs that I would
like to mix down to either traditional stereo or even surround if not
price prohitive.

Awright, what is it that you're not telling us? No normal audio
application uses 8 PCs of which you want to mix the outputs. What's on
each of the PCs, and what's the final product?

The obvious answer to your question is that you need a digital mixer
with 8 S/PDIF inputs (which isn't a standard configuration of any
digital mixer I know of). You can of course add optional interface
cards or use an outboard format converter to convert to ADAT Lightpipe
or TDIF intputs that a modest priced digital mixer might have.

You might also look to see if those PCs also have analog outputs, and
if so, mix them with a more conventional analog mixer. This would be
the most cost-effective way to see if your project even makes any
sense when you actually start mixing from all of these computers
(which I assume you have a way of controlling).

Perhaps a more conventional (by today's standards) method would be in
order. Assuming that there are actual recordings residing on the
computers, as opposed to real-time streaming inputs from a network,
you could simply use a multitrack DAW program on one of the computers,
import the files from all the computers into that program, and use the
program's mixing capabilities. If you wanted multiple outputs for
surround sound, you'd need a sound card in that computer that was so
equippied.

There are cheap solutions and expensive solutions, but first we really
need to know what problem you actually have to solve.



--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
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[xy]

Some budget soundcards (under $400) do have clock sync, so he might
have some luck. But that does seem like a lot of computers!

[Another Mike]

Pooh Bear > wrote in
:

> Another Mike wrote:
>
>> Pooh Bear > wrote in
>> :
>>

>>
>>
>> What about daisy chaining all of them together via spdif and synching
>> each one to the previous. This is assuming the cards can monitor the
>> spdif input on the sodif output, which most can I believe.
>
> SPDIF only carries 2 channels of audio. That's your lot. It wasn't
> designed as a digital routing system, just a low cost link between
> hi-fi separates.
>
> Graham
>

But if you do as I said, the output of the last soundcard will have all 8
spdif streams mixed, as the original poster wanted.

[Rein]

Pooh Bear > wrote in message >...

> Why do you want to mix 8 PCs together btw ?
>
> Graham

Hi Graham,

The PC's are used as synthesisers (with soundblaster audigy) and
controlled with midi. I treat them like synthesisers and they are
analogous to synthesisers in the way I use them. They have traditional
(soundcard) stereo output in 3.5mm stereo jacks. This would be
acceptable to use as line-ins to a powered mixer so that all the
"synths" can be monitored in a performace. However, they also posess a
single RCA-style SPDIF that can be switched from output to input mode
and vice-versa via software. Naturally, digital sound at the 24bit
96KHz format offered is going to sound better and I would love to use
it connected to a PA system that can receive the spdif input. Other
attractive features in such a mixer might be eq, effects, and the
ability to use surround and adjust spatial characteristics of the
sound.

I'm also interested in increasing the distance between the synthesiser
(pc w/ soundcard) and such a mixer so I would want to consider
hardware to alllow transition to optical cabling and optical inputs on
the mixer.

Rein

[Rein]

(Mike Rivers) wrote in message news:<znr1072016020k@trad>...

> Perhaps a more conventional (by today's standards) method would be in
> order. Assuming that there are actual recordings residing on the
> computers, as opposed to real-time streaming inputs from a network,
> you could simply use a multitrack DAW program on one of the computers,
> import the files from all the computers into that program, and use the
> program's mixing capabilities. If you wanted multiple outputs for
> surround sound, you'd need a sound card in that computer that was so
> equippied.
>
> There are cheap solutions and expensive solutions, but first we really
> need to know what problem you actually have to solve.

Thanks Mike but I have never been one to idly accept convention. I
will continue researching how I may aggregate the digital outputs of
each computer. I missed your correspondance when composing my last
reply to this thread (which answers your question) so I'll just
briefly answer the actual problem I'm trying to solve here.

I'm treating each PCwSoundCard as a midi-synthesiser module and how I
use them is entirely analogous to a synthesiser. As with certain
synthesiser modules on the market, the PCwSoundCard setup also has RCA
style SPDIF output (found on a SoundBlaster Audigy 2). So, I had
presumed that since the market posesses a significant share of
synthesisers with digital-output (eg.Proteus2000), certainly there
would be a device to mix those sound sources - or so you would
think... I hope there is something prosumer...
Rein

[Pooh Bear]

Rein wrote:

> (Mike Rivers) wrote in message news:<znr1072016020k@trad>...
>
> > Perhaps a more conventional (by today's standards) method would be in
> > order. Assuming that there are actual recordings residing on the
> > computers, as opposed to real-time streaming inputs from a network,
> > you could simply use a multitrack DAW program on one of the computers,
> > import the files from all the computers into that program, and use the
> > program's mixing capabilities. If you wanted multiple outputs for
> > surround sound, you'd need a sound card in that computer that was so
> > equippied.
> >
> > There are cheap solutions and expensive solutions, but first we really
> > need to know what problem you actually have to solve.
>
> Thanks Mike but I have never been one to idly accept convention. I
> will continue researching how I may aggregate the digital outputs of
> each computer. I missed your correspondance when composing my last
> reply to this thread (which answers your question) so I'll just
> briefly answer the actual problem I'm trying to solve here.
>
> I'm treating each PCwSoundCard as a midi-synthesiser module and how I
> use them is entirely analogous to a synthesiser. As with certain
> synthesiser modules on the market, the PCwSoundCard setup also has RCA
> style SPDIF output (found on a SoundBlaster Audigy 2). So, I had
> presumed that since the market posesses a significant share of
> synthesisers with digital-output (eg.Proteus2000), certainly there
> would be a device to mix those sound sources - or so you would
> think... I hope there is something prosumer...

Ok, with the extra input from you, this kinda makes more sense.

I had an idea this might be what you had in mind actually.

You're stuck with the same problem. The 8 PCs won't be 'in sync', making true
digital mixing impossible.

You have to return to the analogue domain to fix it. There is no 'magic gadget'.

TV studios have had to deal with a similar issue for over 50 yrs. I.e. syncs.

Shame that 'pro-sumer' vendors don't teach anyone the basics !


Graham

[Pooh Bear]

Rein wrote:

> Pooh Bear > wrote in message >...
>
> > Why do you want to mix 8 PCs together btw ?
>
> > Graham
>
> Hi Graham,

Hi Rein !

>
> The PC's are used as synthesisers (with soundblaster audigy) and
> controlled with midi. I treat them like synthesisers and they are
> analogous to synthesisers in the way I use them. They have traditional
> (soundcard) stereo output in 3.5mm stereo jacks. This would be
> acceptable to use as line-ins to a powered mixer so that all the
> "synths" can be monitored in a performace.

Yup, although 3.5mm jacks are hardly to be considered reliable in a live environment. Something you should
consider carefully.

> However, they also posess a
> single RCA-style SPDIF that can be switched from output to input mode
> and vice-versa via software. Naturally, digital sound at the 24bit
> 96KHz format offered is going to sound better and I would love to use
> it connected to a PA system that can receive the spdif input.

I've seen live type mixers with SPDIF/AES output but not input to date. I may have missed something but
certainly none with 8 SPDIFS.

> Other attractive features in such a mixer might be eq, effects, and the
> ability to use surround and adjust spatial characteristics of the
> sound.

Sure, although these are unlikely to be in the pure digital domain, even with a digital mixer. The reason being
that your sources are 'asynchronous'. No digital system can deal with sampling rates that aren't *exactly*
identical without format conversion of some kind. By *identical* I mean *exactly* 44.10000000000...... kHz ( or
whatever ) sampling rate for every source ( and phase locked ! ). Any difference results in clicks, the classic
sign of a poor digitallly mastered session/video/ film etc......


> I'm also interested in increasing the distance between the synthesiser
> (pc w/ soundcard) and such a mixer so I would want to consider
> hardware to alllow transition to optical cabling and optical inputs on
> the mixer.

SPDIF optical cables are good for no more than a few metres due to the cheap parts used. It was designed as
consumer you know !

AES is the only remotely reliable way to get dig audio any distance.


All the best with your project. I would be interested to hear more when you have had a chance to read all of
the advice you have had.

Good luck, Graham

[Mike Rivers]

In article > writes:

> The PC's are used as synthesisers (with soundblaster audigy)

OK, that helps explain things.

> They have traditional
> (soundcard) stereo output in 3.5mm stereo jacks. This would be
> acceptable to use as line-ins to a powered mixer so that all the
> "synths" can be monitored in a performace. However, they also posess a
> single RCA-style SPDIF that can be switched from output to input mode
> and vice-versa via software. Naturally, digital sound at the 24bit
> 96KHz format offered is going to sound better

Don't count on it. Have you tried? And in performance, would it make a
difference? Analog mixing is the way to go here. The Audigy isn't that
bad.

> I would love to use
> it connected to a PA system that can receive the spdif input.

There are none that I know of, but as I said, you can equip a digital
mixer to accomomdate it if you so choose. This has got to be worth a
lot to you in order to take that step though.

> I'm also interested in increasing the distance between the synthesiser
> (pc w/ soundcard) and such a mixer so I would want to consider
> hardware to alllow transition to optical cabling and optical inputs on
> the mixer.

Most people don't feel comfortable using more than about 30 feet of
TOSLink cable. For the cost of RCA-TOSLink adapters, you could get
decent transformers, convert the analog output to a balanced line, and
run it a thousand feet if you wanted to do so.

Digital interfacing is great sometimes, but unless you have the bucks
(in which case I'd assume you'd be using something better than an
Audigy card for your sound source) it isn't always the sensible thing
to do.



--
I'm really Mike Rivers - )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo