RE: AUHAL Full duplex issues
RE: AUHAL Full duplex issues
- Subject: RE: AUHAL Full duplex issues
- From: "Aridis-Lang, Simon" <email@hidden>
- Date: Wed, 11 Aug 2010 15:33:58 +1000
- Thread-topic: AUHAL Full duplex issues
I think I should clarify that I am setting the buffer size using
AudioObjectSetPropertyData using the device id (since
AudioDeviceSetProperty is deprecated), and the max frames per slice on
the AUHAL unit using AudioUnitSetProperty.
My question I think relates to how the buffer size is propagated going
the other way, i.e. when the HAL makes an IOProc callback, I'm guessing
that's being 'routed' through the AUHAL with the buffer size dictated by
the driver, and how the AUHAL unit reconciles that buffer frame size
with it's own max frames per slice if at all.
-----Original Message-----
From: Brian Willoughby [mailto:email@hidden]
Sent: Wednesday, 11 August 2010 3:10 PM
To: Aridis-Lang, Simon
Cc: CoreAudio API
Subject: Re: AUHAL Full duplex issues
On Aug 10, 2010, at 21:38, Aridis-Lang, Simon wrote:
> ... I don't understand why if the AUHAL is an audio unit, and my
> 'IOProc' is registered on the audio unit, why an audio unit
> property is the wrong answer? Could you elaborate on how the AUHAL
> abstracts the HAL and how these two settings interact (is one
> ignored? is it the minimum / maximum of the two?). A lot of
> example code out in the wild is setting both so it would help to
> understand why others have settled on this arrangement.
AUHAL is a convenient translating link between an application and the
HAL, but AUHAL is still completely separate from the HAL. If you
want to change the hardware buffer size, then you need to find the
AudioDevice via a different API and send it the message that Bill
mentioned. I don't think he meant that you could send the HAL
message to the AUHAL and expect it to work, although it might be an
interesting feature to request (i.e. that the output scope of the
AUHAL pass buffer size messages on to the HAL device).
Brian Willoughby
Sound Consulting
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