Re: USB audio device recognized as two devices
Re: USB audio device recognized as two devices
- Subject: Re: USB audio device recognized as two devices
- From: Laurent Cerveau <email@hidden>
- Date: Sat, 1 Dec 2001 10:19:40 +0100
The HAL does not really do anything. The driver does. It depends of
numbers of IOAudioEngine (or more precise og number of instances of the
necessery derived from IOAudioEngine class) that the driver is
presenting. The built in has one IOAudioDBDMAEngine with 2 streams
declared one input and on output ; so this will appear as one device.
Generally streams are grouped on the same engine when they share the
same clock /time base. In USB devices there is often multiple devices in
one box.
Laurent
On Saturday, December 1, 2001, at 05:23 AM, Joe Chang (l %l ,m8) wrote:
>
But I have a question:
>
What makes HAL make one device into two?
>
>
I don't think inputs and outputs are always treated as two seperate
>
devices,
>
because the built-in device has both input and output streams in one.
Laurent Cerveau
Applications Division
Apple Computer Inc.
email@hidden