Subject: Re: [linux-audio-dev] Re: New OSX services & LAAGA
From: Thomas Hudson (thudson_AT_tomy.net)
Date: Wed Jun 06 2001 - 19:49:14 EEST
On Wednesday, June 6, 2001, at 05:00 AM, Francois Dechelle wrote:
>
> Yes, it was a very interesting discussion.
>
> I've already used part of the Apple API, namely the HAL (Hardware
> Abstraction
> Layer) for a first rought porting of jMax to Mac OS X. It is based on
> callbacks,
> the callback being called in a separate thread (this is not documented
> at all).
Yes, it is only slightly better documented for MIDI events, which are
also delivered
through a callback in a mach real-time thread. They do have some nice
features
in the Cocoa framework (NSPort, NSPortMessage) which allow for one to
specify
the object and method to be called in the main thread to receive
delivery of the
events. These are processed in the main event loop.
>
> There is something that is not clear from what I read: is the
> "AudioUnit" API
> for inter-applications communications, or is it a plug-in API ? It looks
> more like a plug-in API.
>
It seems to be more of a plug-in architecture. There seems to be a lot
of higher
level stuff planned that is currently not documented.
> The most interesting thing, IMHO, in what has being discussed yet
> about LAAGA,
> is the idea of inter-applications (i.e. inter-process) audio
> interchange. As far
> as I know, the only system on which this has already existed is BeOS.
> Does anybody know more about it ?
Well, I'm currently employed by someone to port an app from BeOS to
Linux, and
I can say that the pervasive threading model of BeOS poses some
challenges,
especially in the windowing code (every view in Be runs in it's own
thread).
I've looked at their MIDI stuff and wrote some wrappers to emulate their
API's
on top of ALSA, but I haven't dealt much with audio. I'll have a look
and see if
there are any overlooked concepts.
Thomas
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