Re: AUHAL Full duplex issues
Re: AUHAL Full duplex issues
- Subject: Re: AUHAL Full duplex issues
- From: William Stewart <email@hidden>
- Date: Mon, 16 Aug 2010 12:35:43 -0700
On Aug 10, 2010, at 10:33 PM, Aridis-Lang, Simon wrote:
> 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.
AUHAL will update MaxFrames per slice as it needs to based on the IO size of the device and the difference between the client format. This is a little bit different than how MaxFrames normally works, but for AUHAL you can listen to that property changing
>
> 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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