Re: [Alsa-user] Multichannel support - CS4281

[Jaroslav K. <pe...@su...>]

On Thu, 26 Jul 2001, bl...@em... wrote:

> >It's mistake. CS4281 has only three playback channels. Cirrus is probably
> >refering the windows driver which can mix more channels in software.
>
> Three would be nice.  I could use three.
>
> Just for my clarification, are there plans to do any channel mixing in ALSA,
> or any kernel-level software, or are you guys leaving that with esd and
> aRts and whatnot?  I know that the traditional way leaves that stuff to
> user-space, but it seems so much more logical (apart from security) to put
> it at the kernel-level.
>
> >Yes, but the CS4281 hardware has some constraints which needs more code
> >to
> >allow all three streams running simultaneously.
>
> So (pardon my slowness), is there anything I can do now (besides writing
> my own code) to get multichannel support, or should I just be twiddling
> my fingers till the next release?

If I remember correctly, there is only one hardware sample rate converter
for DAC and ADC. It means that three playback streams can work only at
same rate. Also, I don't know, if there is a digital mixer which can
sum the signal from all three streams, too. It seems to me, that the
hardware was designed especially to support 4.0 and 5.1 outputs (DVD
AC3/DTS software decoders and environmental audio).

I think that it was the reason why I postponed any further tests with this
hardware. Actually, I have many other things in my queue, so feel free put
your fingers to this driver.

						Jaroslav

-----
Jaroslav Kysela <pe...@su...>
SuSE Linux    http://www.suse.com
ALSA project  http://www.alsa-project.org