Re: kAudioDevicePropertyBufferSize reported to IOAudioEngine?
Re: kAudioDevicePropertyBufferSize reported to IOAudioEngine?
- Subject: Re: kAudioDevicePropertyBufferSize reported to IOAudioEngine?
- From: William Stewart <email@hidden>
- Date: Tue, 18 Oct 2005 12:36:57 -0700
On 18/10/2005, at 11:35 AM, Daniel Mack wrote:
Hi list,
My today's question is about the interaction between the coreaudio
code in userspace
and kernelspace.
In my IOAudioEngine implementation, I act on some asumptions
regarding the system
speed the driver is running on. The closer I get to a minimum in
the queuing
logic, the higher is the chance that the output starts crackling on
higher system
loads (or with slower machines, of course).
In userspace, it is possible to set an audio device's property by
calling
AudioDeviceSetProperty(..., kAudioDevicePropertyBufferSize,
size, ...);
The information about the amount of data beeing written 'in a row'
could also
be very useful to my kernel extension to take into account whether
lowest audio
latency or lowest system performance usage is more important.
So, long story short, my question is - is there any way to catch
the change
of the buffer size from within a kernel driver?
No - in fact you can have two or more clients simultaneously that are
running at different I/O sizes - for eg, one client is doing 64
sample I/Os, the other 512. This is why it isn't propagated to the
driver.
Bill
I neigther got any hint by grep'ing through the IOAudioEngine,
IOAudioDevice
and IOAudioStream class headers nor by having a look to Apple's own
audio
driver implementations.
Thanks in advance,
Daniel
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