Re: MOTU devices on Intel machines
Re: MOTU devices on Intel machines
- Subject: Re: MOTU devices on Intel machines
- From: Christopher Ashworth <email@hidden>
- Date: Sun, 29 Oct 2006 01:06:29 -0500
On Oct 28, 2006, at 6:14 PM, Kurt Revis wrote:
On Oct 28, 2006, at 6:23 AM, Christopher Ashworth wrote:
I have recently been receiving reports that my users are
encountering problems when using my application with MOTU devices
on Intel machines. In my attempts to track down what might be
going wrong, a variety of factors lead me to wonder if the MOTU
drivers are somehow involved.
Which device (or devices), exactly?
The two I've heard about so far are the MOTU 828MKII and the MOTU
Ultralight.
- My application allows sound designers to play back multiple
sounds during a show.
- Each sound is driven by an AUGraph, with an AUHAL audio unit for
the output.
Are you creating a separate AUHAL for each sound you play?
Yes.
If so, why not just create one, put a stereo mixer AU in front of
it, and then play each sound through a separate input to the mixer?
My understanding is that the intended usage pattern is to use one
output AU and the mixer. You *can* create separate output AUs for
the same device in the same process, and it will work, but it
probably isn't as efficient.
Ah, I see. I had gone with the separate AUHALs for each sound object
because it seemed the object oriented thing to do; each one has its
own resources, independent of the resources being used by other
sounds. No book-keeping needed to track which bus the sound was on,
etc. I didn't realize this was not kosher.
So I should instead have a global AUHAL stored away somewhere, and
attach each sound's render callback to a bus on a mixer in front of
the AUHAL? (I need to use the matrix mixer rather than the stereo
mixer.) Does the matrix mixer allow me to add and delete input
busses while the graph is running?
Odds are that the bug you're hitting now would not happen if you
used a mixer, since all the mixing would be happening in your
process, and the driver level would be completely unaware of how
many sounds you're playing at once.
Agreed--this seems like it could be a good solution. (Or, I guess,
the intended solution...)
Thanks Kurt,
Chris
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