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: Mon, 10 Mar 2008 13:02:06 -0700
On Mar 7, 2008, at 2:06 AM, David Zimmermann wrote:
Hi Jeff,
thanks for reply.
Here are some details.
The hardware Id like to write the driver for is a PCI audio DMA card.
The sources worked fine for another PCI card - now I changed it to
hit our new hardware
specifics too.
The ring buffer size may vary but is for initial tests staticly set
to 160 frames.
That's way too small. The HAL determines the upper bound of the ring
buffer size as 3/8ths the size of your ring buffer. So, you have to
have a ring buffer that is at least 1365 to support the base line 512
sample frame IO buffer size. Lots of apps are going to just fail
outright because of this. If your device supports rates higher rates,
you'll want to have a bigger ring buffer as the default buffer size
for devices with sample rates above 64K is 1024.
--
Jeff Moore
Core Audio
Apple
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