linuxaudio.org

On Fri, 2008-05-16 at 11:20 +0100, J M Needham wrote:

quoted text
> Dear all,

>

> Forgive me for not understanding this, but I've also heard conflicting

> things on Alsa-User. On my PC (old H/W, Ubuntu Hardy Heron, SB audigy) I

> can play sound through apps connected to jack and apps going direct to

> Alsa at the same time. On my Debian sid box, I cannot have two appps

> playing music at the same time. My Laptop, running Ubuntu GG (s/c HDA

> intel) also behaves like this, whereas my friend's PC can do what my

> Ubuntu HH box can do (new H/W, SB Audigy new(ish)), and

> both have been able to do this since we both switched at Edgy Eft.

>

> I don't understand this. Some people say that you cannot play sounds from

> aps connected to Jack and apps not using jack at the same time, which

> contradicts some of my experience and the experience of Joakim Hernberg

> [below] so what's the difference? What files do I need to look at to find

> the difference if there is any.

>

> Is this a h/w or s/w issue? It's clearly possible, so why is there the

> belief that it can't happen?

its both.
there is some audio hardware that supports "multi-open" directly in

hardware. i believe that your SB Audigy is one such device. this means

that multiple (typically somewhere from 8-32) applications can open it,

and the hardware mixes everything down to the outputs.
this type of h/w has become massively less common as Intel-HDA has

spread, since this "specification" leaves mixing like this to device

drivers and/or some OS audio infrastructure. mixing JACK & non-JACK

applications with audio interfaces that do not provide hardware

multi-open is essentially impossible (or just so kludgy that i don't

even want to discuss it).
--p
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