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Re: Mixing in coreaudiod or device driver
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Re: Mixing in coreaudiod or device driver


  • Subject: Re: Mixing in coreaudiod or device driver
  • From: Tim Hewett <email@hidden>
  • Date: Mon, 03 Jun 2013 00:33:47 +0100

Kyle,

That seems to be only for 10.8 or later whereas 10.7/Lion exhibits the same behaviour, though 10.7's CoreAudio.framework was updated Sept 2012 so may contain the relevant changes.

Also the fact that built-in, HDMI and Bluetooth devices continue to behave as before (one user client per app) but USB devices don't suggests all is not as clear-cut as it might appear.

Tim.


On 3 Jun 2013, at 00:00, Kyle Sluder <email@hidden> wrote:

> On Sun, Jun 2, 2013, at 03:35 PM, Tim Hewett wrote:
>> I've noticed recently in IORegistryExplorer that for some devices the
>> output stream mixing now seems to be done in coreaudiod rather than the
>> device driver, i.e. coreaudiod is the only user client to the device
>> engine. Built-in and Bluetooth devices seem to behave normally (each
>> application being a user client) but USB devices and open source devices
>> like AudioReflectorDriver and Soundflower only have coreaudiod shown as a
>> client.
>>
>> Is this down to a matter of configuration, e.g. is there a
>> "setICanDoAudioMixing( bool )" method or a system default setting or such
>> like?
>>
>> It is quite useful to be able to see which apps are using a device,
>> especially those which are active, now apparently only possible under
>> Leopard and Snow Leopard which continue have the original behaviour.
>>
>
> Could it be that you are seeing the effects of the new user-space driver
> architecture?https://developer.apple.com/library/mac/#samplecode/UserLandDriverReference/Introduction/Intro.html
>
> --Kyle Sluder


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References: 
 >Mixing in coreaudiod or device driver (From: Tim Hewett <email@hidden>)
 >Re: Mixing in coreaudiod or device driver (From: Kyle Sluder <email@hidden>)

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