Re: Audio driver outside kernel
Re: Audio driver outside kernel
- Subject: Re: Audio driver outside kernel
- From: Jeff Moore <email@hidden>
- Date: Mon, 7 Nov 2005 11:59:47 -0800
On Nov 7, 2005, at 8:11 AM, try another wrote:
I have been studying the PhantomAudioDriver sample in order to
write my own audio driver. I see that the timerFired
(IOTimerEventSource) is simulating a DMA interrupt. When this
"interrupt" occurs, it means that the currentBlock has been
transferred.
I would like to do this from a userland application. Any
suggestions on how I could do this?
User-land APIs have many timer APIs. Which you use depends on many
factors.
I thought of sharing the outputBuffer and the currentBlock with the
userland app, but I would need to modify the userclient. I don't
think I have access to it; it's provided for me by the IOAudioDevice?
The other problem with this approach is: how do I timestamp the
wrap-around of the ring buffer from the userland app?
Any recommendations?
The IOAudio family is for kernel drivers. You won't be using any of
it's constructs in a user-land driver. In fact, user-land drivers are
very different beasts than IOAudio drivers and are defined by the API
in <CoreAudio/AudioHardwarePlugIn.h>. While it's entirely feasible to
use a model like what the IOAudio family uses, the code you need to
write to implement it is very different.
--
Jeff Moore
Core Audio
Apple
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