Subject: Re: [linux-audio-dev] PortAudio
From: Benno Senoner (sbenno_AT_gardena.net)
Date: Tue Jun 26 2001 - 22:54:16 EEST
On Tue, 26 Jun 2001, you wrote:
> Hello,
>
> > >I would like LAAGA to be a fast, lean, easy to use, higher
> > >level (than the sound driver itself) API that _hides_ the
> > >hardware interface completely from all clients that use it. It
> >
> > I want slightly more than that actually. I want it to hide (like the
> > BeOS MediaKit and the Apple OS-X CoreAudio API) virtually all of the
> > *concepts* associated with a hardware interface as well.
>
> I thought I should point out the existence of an existing cross-platform
> audio API that has been around for awhile. It has been adopted by many
> computer music practitioners. Perhaps it will be useful to some. There is a
> Linux/OSS port in beta. More details at:
>
> http://www.portaudio.com
Athough nice from a portability point of view, it unfortunately does not suit
our needs of a low-latency interapplication communication API.
What LAAGA tries to achieve is an API where each application acts as a
"client" (which can be either a real process or a shared object (a DLL) and can
receive/feed audio data (and control signals) from/to other apps.
For example you fire up the Harddisk recorder, the softsynth and the virtual FX
processor, wire all the components together (including the hardware audio I/O
ports) and have them working all simultaneously in a rock-solid low-latency
fashion.
If you use the in-process model, the system works in a similar way of
Cubase running VST plugins, if you use the out-of-process model, you have
N real apps working at the same time which exchange audio data in realtime
through shared memory areas.
Notice that the in-process model has a bigger chance to deliver extremely low
latencies (in the 2-3msec range) than the out-of-process model because in the
former case there is not any kind of IPC involved.
But even with the out-of-process models, changes are high that we can still
stay in the single digit latency range. (no one has done realworld benchmarks
yet, but my feeling is that sub-10msec is easily possible).
cheers,
Benno.
http://www.linuxaudiodev.org The Home of Linux Audio Development
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