Thanks for your helpful response. 

You could help me even more by answering the following questions: Are audio
callbacks from interrupts in OS X also? How many people actually use OS 9? 

Original Message:
-----------------
From: Anthony Kozar anthony.kozar@utoledo.edu
Date: Wed, 04 Aug 2004 03:47:10 -0400
To: csound-dev@eartha.mills.edu
Subject: [CSOUND-DEV:5142] Re: More on PortAudio and Csound 5 --
feedbackrequested!


On 8/3/04 11:12 PM, Michael Gogins etched in stone:

> I have requested feedback on this situation and not received any. If I
don't
> hear anything from anyone, especially John ffitch, I will proceed as I
think
> best and change the way Csound writes audio and soundfiles.

Sorry, I haven't looked at the code yet (and I should have gone to bed hours
ago and thus may not be thinking straight), but two thoughts come to mind.

1.  rtmacintosh.c, rtcoreaudio.c, rtlinux.c, rtwin32.c, etc. all implemented
the same interface, correct ?  If that interface hasn't changed in CS 5 for
rtpa.c, then couldn't we just continue allow building with the old
implementations for those who want them until these issues with PA are
resolved ?

> The options as I see them are to finish the PortAudio blocking API, or to
> run the Csound performance loop from the PortAudio callback.

2.  Audio callbacks on MacOS 9 are interrupts during which there are severe
limitations such as no allocating or deallocating of memory.  I don't know
how things are implemented exactly in Mac Csound right now, but all audio on
MacOS 9, I thought, is via a callback anyways.  (But I am guessing that the
performance takes place out of the callback and is buffered by Csound for
relaying by the callback).

*shrug* 

I probably don't understand this well enough yet ....

Anthony


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On 8/4/04 9:38 AM, gogins@pipeline.com etched in stone:

> You could help me even more by answering the following questions: Are audio
> callbacks from interrupts in OS X also?

I don't know.  I looked at the CoreAudio docs and really couldn't even find
an example of how to output sound in real-time.  Someone else will have to
answer this.

> How many people actually use OS 9?

My current list of known users only includes four people other than myself.

:(

Anthony
 

I think that I now have an answer to this question (from an Apple Tech Note
"Threading Architectures").

"Traditional Mac OS makes heavy use of asynchronous I/O with I/O completion
routines that are delivered at interrupt time. However, the Mac OS X core OS
does not support a callback-based asynchronous I/O model, and user space
code never runs at interrupt time."

Anthony

On 8/4/04 9:38 AM, gogins@pipeline.com etched in stone:

> Thanks for your helpful response.
> 
> You could help me even more by answering the following questions: Are audio
> callbacks from interrupts in OS X also?