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Re: Built-In devices on single thread



The solution it seems like you are looking for is to create an aggregate device that has all the built-in devices in it. There has been a lot of discussion about using aggregate devices on this list previously.

On Nov 5, 2009, at 8:02 AM, audioboy 77 wrote:

In my application (a pro-audio effect unit/synthesizer), I want to show the Built-In devices as one physical device, with different channels representing the Microphone, Input and Output.

To do this, I use the "related devices" property to find all subdevices and group them together.

I then tried starting an IOProc on the first subdevice (which is the microphone on my system) with the idea that I would read/write the buffers for all the sub-devices in that callback. However, im getting mData which is always NULL. Im not sure if this is expected, but im not sure how to create the buffer. (There is a property to set the buffersize, but no property to get or set the address).

I also tried another approach. I registered each sub-device with the same callback, hoping that the register proc might cause the buffers to get created. When doing this, I have discovered that each subdevice is running on a seperate thread. This is strange given they should be on the same clock, and seems wrong given that I want the latency to be as low as possible.

I've been messing around with this on and off for a couple weeks now, and have basically run out of ideas. Could somebody please explain the correct strategy on how to approach this?


--

Jeff Moore
Core Audio
Apple



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