Re: USB audio driver: one engine, two streams.
Re: USB audio driver: one engine, two streams.
- Subject: Re: USB audio driver: one engine, two streams.
- From: Chuck Carlson <email@hidden>
- Date: Mon, 12 Jul 2010 12:50:06 -0700
Thanks Alison,
Our device is not class compliant so I need to make a few modifications like the way we set our clock and comment out the check for feedback endpoint(which was failing even though we have one and works under windows).
So I need to modify info.plist to get our vendor and product ID recognized but that should be simple and I assume that won't impact getting the two streams into one engine.
--Chuck
On Mon, Jul 12, 2010 at 11:12 AM, Alison Hughes
<email@hidden> wrote:
Chuck,
If you use our class driver, there is no need to modify the info.plist - AppleUSBAudio will attempt to put the streams on a single engine automatically depending on the device configuration. From the section titled "Unified Engine Model" in our tech note "USB Audio on the Mac":
In order to combine multiple streams on one engine, the following criteria must be met by the stream interfaces:
• All sample rate sets must match.
• The same synchronization type is used for all interface alternate settings.
• The streams reside in the same clock domain.
See <https://developer.apple.com/mac/library/technotes/tn2010/tn2274.html#TNTAG3> for more info.
Thanks,
Alison
--------------------
Alison Hughes
CPU Software Engineering (Audio)
Apple, Inc.
On Jul 11, 2010, at 8:46 PM, Chuck Carlson wrote:
> Hello,
>
> A while ago I implemented our usb audio driver for 10.5.6. Our device requires one audio engine with two streams. This required much ugly butchering of the standard apple driver.
>
> Now I'm doing the same job, but with the latest driver, AppleUSBAudio-273-4.1 for 10.6.4. The model now supports input and output streams in one engine. (seems this is true since 10.5.7).
>
> What's the simplest way to do this?
>
> I'm assuming there is something simple to put into the info.plist which will cause the iokit matching to put the streams into one engine, but can't figure it out.
>
> Thanks for any pointers,
>
> --Chuck
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