From alsa-devel-owner@alsa.jcu.cz  Thu Mar 19 17:48:16 1998
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Date: Thu, 19 Mar 1998 17:48:02 +0100 (MET)
From: Jaroslav Kysela <perex@jcu.cz>
To: Marcus Brinkmann <Marcus.Brinkmann@ruhr-uni-bochum.de>
cc: alsa-devel@alsa.jcu.cz
Subject: Re: New Feature Idea
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On Tue, 17 Mar 1998, Marcus Brinkmann wrote:

> On Tue, Mar 17, 1998 at 02:39:03PM +0100, Jaroslav Kysela wrote:
> > On Tue, 17 Mar 1998, Marcus Brinkmann wrote:
> > 
> > > I'm more interested in API C++ libraries than in low-level programming, so I
> > > could give it a try, too. There are a couple of questions I have about your
> > > project, but this can wait.
> > 
> > Ask me (and others) in this list if you want something. Project is still
> > in initial stage and we can still make some big changes in ALSA kernel
> > API.
> 
> I'm very lucky that there is such a project. My hope for good sound apps
> under Linux vanished more and more with every line I saw in
> linux/drivers/sound.
> 
> > > I attach a mixer class I wrote for OSS. I think I could reimplement it for
> > > ALSA quite fast.
> > 
> > I'm waiting on your comments about current ALSA MIXER API...
> 
> I have a quick question right now: I saw a volume interface for percentage
> (0-100) and dezibel. There is a rounding problem when scaling the 0-100 to
> the real bounderies. What about a request function to get the maximum
> values? It would be more exact, IMHO. I'm sorry if I missed something, as I
> didn't had a close look at the source code yet.

Should be... I'll try make this change soon... Some hardware needs native
volume in exponential form (GUS for example), too... But this is too hard
implement all possible types to kernel API, so lowlevel code must doing
translation from linear value to hardware value.

> > Any other ideas?
> 
> * How much compatibilty to OSS do you want to achieve (will ALSA be a drop-in
> replacement) ?

Yes, it will be.. Some OSS interfaces can be emulated over add-on modules
(such as PCM).. At this time mixer & PCM interfaces are complete 
emulated (Quake for example is working perfectly), so OSS binaries can
be used without change. I assume that raw midi interface + raw FM/OPL3
interface will be emulated, too.. The question is, if we will emulated OSS
sequencer (level 1&2), too. I think that this interface is too much broken
for serious sound. Have anyone other comments?

> * I would suggest exceptions for error handling in the C++ lib. gcc 2.7 has
> problems with it, but it is the way to go.

Fine...

					Jaroslav

-----
Jaroslav Kysela <perex@jcu.cz>
Academic Computer Centre, University of South Bohemia
Branisovska 31, C. Budejovice, CZ-370 05 Czech Republic



