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RE: How do you play four channels?

Date1998-01-23 12:59
FromChristopher Neese
SubjectRE: How do you play four channels?
In theory, opening two soundcards and operating them in parallel is 
possible.  However there are two catches to using multiple soundcards.

First, most soundcards are not very fond of other soundcards in a system. 
 Installing two SoundBlaster cards is asking for some resource headaches, 
if you can get it to work.  (I am speaking from personal experience with an 
SB32 and SB AWE32.)  The problem is that most soundcards are multi-purpose 
resource hogs.  With more professional cards, which are designed purely for 
Audio, one usually doesn't have this problem, but these cards aren't 
necessarily good for general windows sound system use.  Most people would 
probably be happiest with a "professional" card for their Csounding, and a 
SoundBlaster type card for general multimedia support.  At this point, one 
does have two soundcards installed, but most likely getting a four or eight 
channel "professional" card doesn't seem so expensive anymore.

The other problem is that PCI soundcards are inherently better than ISA 
soundcards for real time digital synthesis.  I don't think there is any 
way, no matter how fast your computer is, that you could have two ISA 
soundcards playing in parallel at 44100 stereo without dropouts.  I have 
very drastic performance differences when I use my PCI AudioWerk8 for real 
time performance over when I use my AWE32 for real time performance.  This 
brings up the problem that a lot of Csounders aren't going to have room for 
two PCI cards, and again, the price difference between two stereo PCI cards 
and one PCI multichannel cards is slight.

Anyway, it is definitely still worthwhile to write software for using sound 
cards simultaneously.  There are quite a few people who have multiple 
cards.  However, I don't recommend that anyone run out and buy a second 
soundcard so that they can do quadraphonic sound anytime soon, without 
considering the above performance issues.

Christopher Neese




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From: J P Fitch 
To: csound@maths.ex.ac.uk
Subject:  Re:  Raising to the power?
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What is wronhe pow opcode?  It has been there for years.
==John



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Subject: Re: How do you play four channels?
To: Csound mailing list 
Date: Fri, 23 Jan 1998 11:38:56 -0500 (EST)
From: Eli Brandt 
In-Reply-To: <01BD27D4.D1D3A360.Christopher.Neese@oberlin.edu> from "Christopher Neese" at Jan 23, 98 07:59:23 am
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Christopher Neese wrote:
> 
> In theory, opening two soundcards and operating them in parallel is 
> possible.  However there are two catches to using multiple soundcards.

A third catch for good measure: their clock crystals will drift.
General solutions to this are expensive, and limited solutions are annoying.

-- 
     Eli Brandt  |  eli+@cs.cmu.edu  |  http://www.cs.cmu.edu/~eli/



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Date: Thu, 22 Jan 1998 18:23:05
To: Per Villez , csound@maths.ex.ac.uk
From: Hans Mikelson 
Subject: Re: Raising to the power?
In-Reply-To: 
References: 
 
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There are the opcodes ipow, kpow and apow.




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From: Richard Dobson 
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To: Eli Brandt 
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Subject: Re: How do you play four channels?
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I have found no problem with simultaneous (asynchronous) playback of 44K
stereo from two soundcards, on my P133 system (Soundblaster clone and
DAL CardD, both ISA); my guess is that the hard disk system is the more
critical factor. If I start one card playing, then ask the second to
prepare a sound, a short glitch is induced in the first sound as the
disk is accessed. Thereafter playback on both is clean. If the files for
both cards are opened together (as they would be for pseudo-4ch
playback), even this problem disappears. I am using a Micropolis AV SCSI
drive.

The key to generic 4channel playback must be card driver, which must
offer the necessary channels. Even when I ask MediaPlayer to play a 4ch
soundfile, it does not reject it out of hand, but merely informs me the
driver cannot accept that format. If wave devices are listed as
supporting only stereo (even if there are several of them), the Windows
Wave Mapper will not find a single device which supports the format.

Microsoft would simply describe a 4channel file as a 'non-standard
format', but perfectly reasonable in principle. Indeed, the 48KHz sample
rate is a 'non-standard' format as far as they are concerned!

One possibility for the PC in the future (apart from the Csound card) is
the Codec97 specification, which is designed to support multi-channel
digital audio via USB and firewire:

http://developer.intel.com/pc-supp/platform/ac97/index.htm

Some companies have reached the stage of producing chip sets for this
(Harris, and possibly also Analog, though I haven't checked).

Behind all this lies the need to determine some new standard and
portable  multi-channel format, which card manufactuers can reasonably
be invited to support - six channels as a minimum (for AC3), but
probably eight as a 'round number' and compatible with ADAT, for
example. I would be surprised, in fact, if something along these lines
is not already being hatched behind the scenes - does anybody 'know'
anything in this respect?  It will probably be a toss-up between some
emergent de-facto standard, or some ex cathedra directive from
Microsoft. Perhaps even Apple are working on something?

Perhaps this is an issue in which the Csound community at large can take
the initiative and press manufacturers (and even Microsoft/Apple etc) to
go the extra mile and produce drivers for their multi-channel cards,
which will accept a single file up to the maximum channel width their
hardware will support, rather than, as seems to be the case at present,
present the hardware in terms of so many stereo devices.

Richard Dobson


Eli Brandt wrote:

> Christopher Neese wrote:
> >
> > In theory, opening two soundcards and operating them in parallel is
> > possible.  However there are two catches to using multiple
> soundcards.
>
> A third catch for good measure: their clock crystals will drift.
> General solutions to this are expensive, and limited solutions are
> annoying.
>
> --
>      Eli Brandt  |  eli+@cs.cmu.edu  |  http://www.cs.cmu.edu/~eli/






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Date: Sat, 24 Jan 1998 12:19:29 +0100
From: trkkaZulu 
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High;

It's me again. Is there a Cecilia list?  Thanks for all the help Khalid.

trkkaZulu

--
Visit: http://home1.swipnet.se/~w-18884/gtc/homePage.htm
radical raid rocker independent oop shockwave cybernation





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Date: Sat, 24 Jan 1998 11:21:02 +0000
To: csound@maths.ex.ac.uk
From: Per Villez 
Subject: Re:  Raising to the power?
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Aha!. Thanks John. Funny though, that this 'pow' opcode should be after the
Reverb opcodes in the manual and no where near the value converters
(log,exp etc). It wasn't in the place I expected it to be, but many thanks
for the info

			per


>What is wronhe pow opcode?  It has been there for years.
>==John




Date1998-01-23 16:38
FromEli Brandt
SubjectRe: How do you play four channels?
Christopher Neese wrote:
> 
> In theory, opening two soundcards and operating them in parallel is 
> possible.  However there are two catches to using multiple soundcards.

A third catch for good measure: their clock crystals will drift.
General solutions to this are expensive, and limited solutions are annoying.

-- 
     Eli Brandt  |  eli+@cs.cmu.edu  |  http://www.cs.cmu.edu/~eli/