svlug_linux_sound_interface_internals

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Date: Wed, 21 Feb 2001 12:03:48 -0800
From: Rick Moen <rick@linuxmafia.com>
To: Silicon Valley LUG <svlug@svlug.org>
Subject: Re: [svlug] Maximum Linux dead

begin Dagmar d'Surreal quotation:

> While the ioctls might be the same for the *basic* stuff, we now have
> two competing approaches to sound drivers, OSS and ALSA and they
> aren't very compatible with each other.

Hmm.  I knew that they are not mix-and-match with one another, but was
pretty sure they presented the same interface to programs.  I'm curious,
and hope you won't mind detailing this further.

> I, however, have an SBLive! card and would kinda like the ability to
> at least do positional control of audio streams so that I can do
> things like say, have my system noises come out the front speakers and
> my MP3s play from the rear nearer my bed.  It can't be done under
> Linux at the moment (without severe hacks) in part because there's not
> even an API available for attempting to do stream placement (that I am
> aware of).

This sounds like, really, a hardware-vendor problem.  I could be wrong,
but doubt that a hardware-independent protocol for this is very
feasible.  (But I'm certainly no expert at this.  Just a hunch.)

===


Date: Wed, 21 Feb 2001 13:59:38 -0800
From: Erik Steffl <steffl@bigfoot.com>
To: Silicon Valley LUG <svlug@svlug.org>
Subject: Re: [svlug] Maximum Linux dead

Rick Moen wrote:
> 
> begin Dagmar d'Surreal quotation:
> 
> > While the ioctls might be the same for the *basic* stuff, we now have
> > two competing approaches to sound drivers, OSS and ALSA and they
> > aren't very compatible with each other.
> 
> Hmm.  I knew that they are not mix-and-match with one another, but was
> pretty sure they presented the same interface to programs.  I'm curious,
> and hope you won't mind detailing this further.

  alsa and oss are completely different, however, alsa offers oss
emulation, so programs can use /dev/dsp or /dev/audio and other oss
devices that work exactly (well, for most practical purposes) as if oss
drivers were handling them (works OK, as far as I can tell, all programs
that I tried that use oss work). alsa is much better design but changes
rapidly (it's not ready yet), it's much more flexible... the alsa native
devices have different names (it offers audio, midi, mixer interfaces
that are different from oss devices).

> > I, however, have an SBLive! card and would kinda like the ability to
> > at least do positional control of audio streams so that I can do
> > things like say, have my system noises come out the front speakers and
> > my MP3s play from the rear nearer my bed.  It can't be done under
> > Linux at the moment (without severe hacks) in part because there's not
> > even an API available for attempting to do stream placement (that I am
> > aware of).
> 
> This sounds like, really, a hardware-vendor problem.  I could be wrong,
> but doubt that a hardware-independent protocol for this is very
> feasible.  (But I'm certainly no expert at this.  Just a hunch.)

  instead of mono or stereo channels the alsa (and partially oss, AFAIK)
offer certain number of channels, so that would be two channels for
stereo card, four channels for sblive, even more channels for audio
cards (hammerfall?), or something like that.

	erik

===


Date: Wed, 21 Feb 2001 13:51:48 -0800 (PST)
From: "Dagmar d'Surreal" <dagmar@dsurreal.org>
To: Don Marti <dmarti@zgp.org>
Subject: Re: [svlug] Maximum Linux dead

On Wed, 21 Feb 2001, Don Marti wrote:

> On Wed, Feb 21, 2001 at 11:28:32AM -0800, Dagmar d'Surreal wrote:
> 
> > do stream placement (that I am aware of).  Hopefully Creative might take
> > the initiative soon and come up with an API for the emu10k driver and get
> > the ball rolling on that stuff.
> 
> Creative and Loki are doing a cross-platform "OpenGL for Audio" called
> OpenAL.  It's under the LGPL.
> 
> http://www.openal.org/
> 
> Supported platforms so far are Linux and Microsoft Windows.

Ah!  That's very good news indeed.  I knew OpenAL was a new audio library,
but I didn't know they had intentions to deal with positional placement on
the more advnaced cards (which are pretty disgustingly cheap now).


===

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