Re: [LAU] ALSA to pulseaudio

On Tue, Oct 27, 2009 at 10:29:10PM -0400, Paul Davis wrote:

> On Tue, Oct 27, 2009 at 7:15 PM, Jonathan E. Brickman
> <jeb@email-addr-hidden> wrote:
>
> > Well, it is clear that I have to do something different than pure
> > Jack/ALSA.  I'll try Pulse, although Pulse's reputation for low latency
> > isn't exactly stellar.
>
> the ALSA jack plugin has poor latency too. anything that has to
> intermediate between a "push" model API (where the app gets to decide
> when and how much data to read/write) and a "pull" mode (where
> something other than the app makes those decisions) has to have enough
> buffering to deal with the app's intentional and unintentional
> behaviour. it probably isn't as latency inducing as pulse's default,
> but its not a replacement for using JACK directly.

If ALSA gets its part right, the resulting latency will
just depend on how the app uses the ALSA interface, as it
does for a normal ALSA device. If the app does so in the
same way as e.g. Jack's backend, there should not be any
additional latency at all.

If ALSA can make a low-latency interface on top of an
interrupt routine or thread that runs every period and
is triggered by the soundcard, then (as a Jack client)
it should be able to provide the same low-latency
interface on top of the process callback which just
looks like a soundcard interrupt handler in user space.
There is no essential difference between the two.

Ciao,

-- 
FA
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