sndio multiple interfaces

classic Classic list List threaded Threaded
3 messages Options
Reply | Threaded
Open this post in threaded view
|

sndio multiple interfaces

Ken MacKenzie
Been looking around and can't find the answer to this question. If I missed it
in some obvious place please excuse me.

Anyway I am curious if sndio can support multiple simultaneous cards, either
identical or different, particularly multiple standards compliant USB audio
interfaces. Basically I am asking if it supports similar features to what one
might use zita with jack on a linux system.

Part of the reason I am diving into OpenBSD is sndio. I find it a breath of
fresh air after years of ALSA+Jack "fun..."

Ken

Reply | Threaded
Open this post in threaded view
|

Re: sndio multiple interfaces

Alexandre Ratchov-2
On Sun, May 20, 2018 at 06:49:25PM -0400, Ken M wrote:
> Been looking around and can't find the answer to this question. If I missed it
> in some obvious place please excuse me.
>
> Anyway I am curious if sndio can support multiple simultaneous cards, either
> identical or different, particularly multiple standards compliant USB audio
> interfaces. Basically I am asking if it supports similar features to what one
> might use zita with jack on a linux system.

This doesn't work with sndio. It's difficult to make work because each
audio interface would use its own clock source, and clocks would drift
sooner or later. Drift may be corrected, but this would cost
additional latency, complexity and (probably) quality problems.

That's why certain devices have a "word clock", to allow audio devices
to by synchronized; OpenBSD doesn't support any of them, but
supporting them looks much easier than combining multiple devices.

Nowadays many-channel devices are common, so supporting multiple cards
as one isn't that important, is it?

Reply | Threaded
Open this post in threaded view
|

Re: sndio multiple interfaces

Ken MacKenzie
On Tue, May 22, 2018 at 07:56:31AM +0200, Alexandre Ratchov wrote:

> On Sun, May 20, 2018 at 06:49:25PM -0400, Ken M wrote:
> > Been looking around and can't find the answer to this question. If I missed it
> > in some obvious place please excuse me.
> >
> > Anyway I am curious if sndio can support multiple simultaneous cards, either
> > identical or different, particularly multiple standards compliant USB audio
> > interfaces. Basically I am asking if it supports similar features to what one
> > might use zita with jack on a linux system.
>
> This doesn't work with sndio. It's difficult to make work because each
> audio interface would use its own clock source, and clocks would drift
> sooner or later. Drift may be corrected, but this would cost
> additional latency, complexity and (probably) quality problems.
>
> That's why certain devices have a "word clock", to allow audio devices
> to by synchronized; OpenBSD doesn't support any of them, but
> supporting them looks much easier than combining multiple devices.
>
> Nowadays many-channel devices are common, so supporting multiple cards
> as one isn't that important, is it?

OK, noted. The question was about a feature parity against a library in linux.
Zita is a tool to help overcome the clock drift. Truth is in practice it is less
than reliable so a single interface is better in practice.

Thank you.
Ken