Subject: [linux-audio-dev] Re: New OSX services & LAAGA
From: Paul Davis (pbd_AT_Op.Net)
Date: Wed Jun 06 2001 - 13:44:49 EEST
Thomas Hudson wrote:
>What I thought was especially interesting is their AudioUnits API. Seems
>like they're specify a unit generator or LADSPA-type plugin system at the
>OS level, though it is a pull I/O model.
I hope everyone took the oppurtunity to review Apple's specs. I have
not, because I don't want to be "contaminated" at this point. Because...
I am *VERY* excited.
Two days ago, I sat in the Piazza della Republica in Firenze with
Francois Dechelle (IRCAM/jMax), and we talked in great detail about
the whole LAAGA issue, plugin/component models and the OS-X audio API
(Francois has already had extensive experience (relatively speaking)
with the OS-X audio API).
I believe (and I think Francois does too, but I don't speak for him)
that there is now ample justification for every element of LAAGA's
conceptual design to become the primary audio API for Linux. The
callback model (Thomas calls it a "pull model" above, but I prefer
"callback" since for capture this is actually a "push model") is
firmly entrenched in ASIO, every plugin system under the sun including
DirectX, and now OS-X. It may even be part of the BeOS audio API. The
use of floats as a universal standard for audio data is also present
in most other APIs, including IRIX which for years was (and perhaps
is) by far the most advanced Unix-like OS when it came to
multimedia. Finally, the model that most applications (generally) do
not alter hardware settings such as buffer size, sample rate and so
forth, is well established on all versions of Windows and MacOS (*)
During the somewhat arduous 2 day journey back from Firenze, I have
written most of the code to define and implement an extremely simple
audio API that embodies most of what we've spoken of here over the
last few weeks. During the day today, I hope to type it in and send it
in for your review.
The work that Abramo has done on the ALSA PCM "shm" device will ensure
that applications which do not wish to adopt this model will be able
to work even on a system that has a LAAGA-like audio engine
controlling the only audio interface. If it was not for his work on
this, it would be much harder to propose the fundamental change in
audio APIs that I'm about to do.
I'd also like to note that in the last 4 weeks I have actually managed
to have face-to-face meetings with:
Dave Phillips
Richard Furse
Francois Dechelle
Maurizio Umberto Puxeddu
Gunter Geiger
and others. The sense that there really *is* a Linux Audio Developers "group"
feels much more tangible to me right now.
excitedly,
--p
(*) I actually think that ALSA may have made a basic design error in
this area, but its not a serious one in that it can be conveniently
glossed over in various ways. ALSA needs to be a general purpose API
anyway, and in that sense its probably better that it continues to
support the OSS tradition of "open; set parameters; use; close" rather
than enforce the "open; use; close" paradigm.
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