Re: [AD] mixers gone?

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On Mon, Apr 28, 2008 at 6:25 PM, Peter Wang <novalazy@xxxxxxxxxx> wrote:
> On 2008-04-28, Ryan Dickie <goalieca@xxxxxxxxxx> wrote:
>  > On Mon, Apr 28, 2008 at 4:23 PM, Peter Wang <novalazy@xxxxxxxxxx> wrote:
>
> > >  But since the code is there (or would be there) anyway, we might as well
>  > >  allow the user to use it in some preprocessing stages.  I agree that it
>  > >  should be transparent for the common case where you just want to play
>  > >  some sounds.
>  >
>  > What kind of preprocessing do you have in mind? Are there some use
>  > cases you can think of?
>
>  I don't know if this would work, but say you're standing outside a cave
>  and you have an NPC talking to you, but you can also hear water and
>  gunfire coming from inside the cave.  You could mix together the water
>  and gunfire together, run that through an echo-type filter then play
>  that filtered sample alongside the unfiltered NPC speech.
>  Actually, that would be a nice little example program ;-)
>

You can apply the echo filter to the gunfire and water separately
without changing the result. And yes, that would make a nice example
program.

>
>  > >  ALSA dmix is not necessarily enabled, and OSS never had such a thing
>  > >  (and we need that to support the *BSDs, I think) so as a practical
>  > >  matter we need a mixer anyway.  It's not particularly complicated code,
>  > >  is it?
>  > >
>  >
>  > Well the ALSA claims the dmix has been enabled by default since
>  > version 1.0.9rc2. From what I have found, that version was released
>  > about 3 years ago.
>
>  Well, it never seems to work on my brother's machine.  Actually my sound
>  card supports hardware mixing so I haven't had to deal with it for a
>  while so I might be out of date.
>

Well, one problem is with software that uses OSS drivers because they
hog the sound card. Apparently dmix works with oss-emulation just
fine. I haven't heard of any other problems.

>
>  > Sure OSS is pretty much raw control over the sound device. Even two
>  > applications trying to play a sound at the same time have to fight
>  > over it. I can copy the mixer code into a new oss.c file in case any
>  > one wishes to use it for that architecture.
>
>  Why not leave the mixer code platform- and driver-independent, as it
>  already was?  Even if you don't expose it to the user that would be
>  more sensible.
>

To be honest, i only meant to disable it temporarily until after i was
done refactoring. But once i finished the code cleanup, I found no
place for it. It was redundant.

I think it might be useful to provide a converter/filter that
downmixes from higher channels if the audio driver doesn't support it
(say downmix 7.1 to 2 channels). I never got the original mixer to
work for that but it was a single function and someone could polish
it.  The sound driver itself should handle the blending of voices
automatically. I also feel that this downsampling should be handled
automatically.

>
>
>  Peter
>
>
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