Re: Implementing a filter driver for a USB Audio compliant device
Re: Implementing a filter driver for a USB Audio compliant device
- Subject: Re: Implementing a filter driver for a USB Audio compliant device
- From: Mark Cookson <email@hidden>
- Date: Mon, 07 Mar 2005 09:58:42 -0600
The Mac doesn't have a concept of filter drivers, so that's not going to
work...
However, when I updated the AppleUSBAudio driver for 10.3.x (where x > 3, if
memory serves), I added the ability to have a "plug-in kext" operate hand in
hand with AppleUSBAudio, specifically for the purpose of doing DSP work for
input and output. The plugin kext is a simple kext with some basic entry
points that will be loaded and called by AppleUSBAudio.
I left Apple before I really got a chance to document, though I did send a
write up and sample code to Jason Seng in Developer Technical Support.
If you're adventurous, I suggest that you download the latest AppleUSBAudio
driver and look for "mPlugin". You'll find all the instances of where
AppleUSBAudio calls the plugin and you should be able to figure out what to
do from there.
Good luck, and let me know how it goes! I'm not aware of anyone actually
using this functionality (though the sample plugin kext worked, so I'm
pretty sure you can get it to do what you want), so you might be the first.
:-)
--
Mark Cookson
M-Audio, a division of Avid
225 Locust St.
Hudson, WI 54016
On 3/5/05 2:46 PM, "Robert Kukuchka" <email@hidden> wrote:
> Hello,
> I'm working on a project in which the requirements are to take a
> USB Audio compliant device, and for the vendor's specific product have
> some very simple DSP related tasks performed on the incoming audio
> before it is reported as an input device. Our windows developer has
> finished his version using a Filter Driver. Could someone point me in
> the right direction for the Mac side of things? I've been reading over
> the device driver sections of the documentation and I get the
> impression I need to use a Device Interface? I'll admit to be being a
> bit new at the lower level stuff, so any help is greatly appreciated
> here. I realize I'll need to go over things with a fine tooth comb,
> being I'm going to be communicating with some things beneath user mode.
> Thanks in advance.
>
> Cheers
> ~Rob
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