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Re: A simple 'Device Through' app (need some help).
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Re: A simple 'Device Through' app (need some help).


  • Subject: Re: A simple 'Device Through' app (need some help).
  • From: Brian Willoughby <email@hidden>
  • Date: Sat, 28 Jun 2008 03:41:38 -0700

Hi Glenn,

If you're willing to do the extra work, programming directly to the HAL is certainly possible. You'll have to do more SRC if you data doesn't match the device, and you'll have to register for lots of changes that the AUHAL will automatically handle, but it's certainly possible. If you want to benchmark CoreAudio against Portaudio, then I guess you're heading in the right direction. AUGraph won't talk directly to the HAL, or at least that's my guess. Thus, you'll need to feed the callback routines for both input and output devices, along with any AudioConverters.

I can't remember which example I looked at when writing directly to the HAL, but you can perhaps use HAL/HALLab and HAL/Million Monkeys as references.

Brian Willoughby


On Jun 27, 2008, at 23:54, Glenn McCord wrote: We've already got Portaudio working. Now we're trying to squeeze out just a little bit more performance by using core audio directly. I like Portaudio; it's just that we don't actually know how much better coreaudio is compared to portaudio unless we get both running and compare them.

On Sat, Jun 28, 2008 at 4:09 PM, Norman Franke wrote:
Or you can just use Portaudio, which is available for Mac OS X using Core
Audio. I use it with the PJSIP VoIP library and it works great.


On Jun 27, 2008, at 11:08 PM, Glenn McCord wrote:
This is not the news I wanted to hear. Looks like I will have to have
another hack at getting CASimplePlayThrough to do what I want. Yes,
the devise is USB and the AudioDeviceID that core audio spits out are
different for the input and output.

In regards to the HAL; I know it won't be simpler, I just wanted to
know if it's possible because all the docs I see use Audio Units
which, according to the diagrams, is a fair amount of abstraction.
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References: 
 >A simple 'Device Through' app (need some help). (From: "Glenn McCord" <email@hidden>)
 >Re: A simple 'Device Through' app (need some help). (From: Brian Willoughby <email@hidden>)
 >Re: A simple 'Device Through' app (need some help). (From: "Glenn McCord" <email@hidden>)
 >Re: A simple 'Device Through' app (need some help). (From: Norman Franke Lists <email@hidden>)
 >Re: A simple 'Device Through' app (need some help). (From: "Glenn McCord" <email@hidden>)

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