Re: Full duplex in sound driver?

Gregory Maxwell (linker@z.ml.org)
Tue, 25 Aug 1998 02:23:10 -0400 (EDT)


On Tue, 25 Aug 1998, Richard Gooch wrote:

> Alan Cox writes:
> > > > The SB16 can do full duplex, but you have to jump through hoops to do it.
> > > > And the result isn't all that great, from what I've heard.
> > >
> > > Can you elaborate? Is there crosstalk between the input and output, or
> > > other such hardware limitations?
> >
> > You are stuck with 8bit in one direction, 16bit in the other, the
> > two channels arent that independant on rates etc either
>
> Are you saying that the samples are limited to 8 bit one way and 16
> the other way?
> Or are you just saying that there are twice as many DMA cycles in one
> direction?

Nope, you get 8bit/sample in one direction and 16bits/sample in the other.

It's good enough for internet phone apps.

> > Within the limits its still very useful and I consider it a flaw
> > we dont support it. Its well good enough for stuff like internet voice
> > apps
>
> I had a quick play with 8 bit voice and there was a bit of
> distortion. With 16 bits it was fine. Haven't had time to play with it
> any further, though.

Voice is okay with linear 8 bits. But it would be nice if the SB16 could
at least do 16bit linear and give 8bit ulaw, that sounds quite a bit
better. Oh well..

What cards does Linux support full duplex on?

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