Re: getting 'kAudioDevicePropertyBufferFrameSize' may reflect invalid values
Re: getting 'kAudioDevicePropertyBufferFrameSize' may reflect invalid values
- Subject: Re: getting 'kAudioDevicePropertyBufferFrameSize' may reflect invalid values
- From: Jeff Moore <email@hidden>
- Date: Thu, 6 Mar 2008 12:20:35 -0800
You missed adding details to your email so that we can help you figure
out what's going on. It would be nice to know something about the
audio device you are supporting, specifically what the stream layout
looks like as well as what the data formats are. It would also be nice
to know the size of your ring buffer in sample frames.
At any rate, HALLab just reports what the HAL tells it. It sounds like
your driver is reporting unusual values for things to the HAL. This is
probably why other apps are failing with your driver.
On Mar 6, 2008, at 2:40 AM, David Zimmermann wrote:
I`m writing an IOKit audio hardware driver.
I tested the driver with the HALLab tool and experienced problems.
The app seems to assume a wrong size in frames of my hardware sample
buffers.
The arguments to my IOProcs pointed me to that conclusion.
I reflect my hardwares sample buffer size in frames via
IOAudioEngine::setNumSampleFramesPerBuffer
within my subclasses initHardware.
Debugging the HALLab shows that the Audio HAL reflects valid sample
buffer ranges (kAudioDevicePropertyBufferFrameSizeRange) but
the reflected current buffer size may be out of range
(kAudioDevicePropertyBufferFrameSize) and thereby invalid.
For testing purposes I changed the HALLab source to limit every HAL
reflected "kAudioDevicePropertyBufferFrameSize" against
the range and reset the property with that limited value.
Afterwards HALLab works fine with my driver.
But no other app does...
What do I miss ?
--
Jeff Moore
Core Audio
Apple
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