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Re: USB Class compliant driver in Leopard
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Re: USB Class compliant driver in Leopard


  • Subject: Re: USB Class compliant driver in Leopard
  • From: Lubor Prikryl DS <email@hidden>
  • Date: Thu, 27 Mar 2008 21:18:18 +0100

Hi Jeff,

Thanks for your response. I tried to use several devices, always on Intel Macs. The devices were M-Audio FastTrack (with uninstalled custom drivers), Crate Profiler and some more. They completely mute output if I set the buffer size <= 128. We use AudioUnits for input and output.

When I installed M-Audio drivers for FastTrack, the lower buffer size started to work OK.

I performed this test:

I have added a set property call to your ComplexPlayThru exaple, when I had set bufferSizeFrames = 64, the devices using USB CC driver did not work.
However, the Reset call fixed something and the device started to play.


Doing the same with buffer size 256, the device started to work immediately.

I am aware of the principle that USB CC have separated input and output, so I am handling both parts independently in our codes.

Thanks for any hint.

Lubor Prikryl
DSound (CZ)
Managing Director
email@hidden




On 27.3.2008, at 19:50, Jeff Moore wrote:
You'll have to define "doesn't work" a little better. I have an Edirol UA-3 here in my office that I seems to run just fine with an IO buffer size of 32 frames.

On Mar 27, 2008, at 11:17 AM, Lubor Prikryl DS wrote:

I have noticed, that the class compliant USB audio driver doesn't work with smaller buffer sizes in Leopard (under 128 samples). There was no such limitation in Tiger. Is this a known issue or has it some workaround?

(The class compliant FireWire driver works perfectly, this is great!)



--

Jeff Moore
Core Audio
Apple


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References: 
 >USB Class compliant driver in Leopard (From: Lubor Prikryl DS <email@hidden>)
 >Re: USB Class compliant driver in Leopard (From: Jeff Moore <email@hidden>)

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