Re: Cannot set channels number for the output of a USB audio 2.0 class compliant device
Re: Cannot set channels number for the output of a USB audio 2.0 class compliant device
- Subject: Re: Cannot set channels number for the output of a USB audio 2.0 class compliant device
- From: Brian Willoughby <email@hidden>
- Date: Sat, 02 Apr 2016 19:56:55 -0700
Philippe,
On Mar 31, 2016, at 6:40 AM, Philippe Wicker <email@hidden> wrote:
> On 31/03/16 07:17, Brian Willoughby wrote:
>> https://developer.apple.com/library/mac/technotes/tn2274/_index.html
>>
>> Another aspect of your question seems to revolve around whether you can tie the number of input channels to output channels. I haven't reviewed the USB Audio 2.0 specifications looking for this particular answer, but I suspect that you'll need to represent your requirements in the USB Descriptors before OSX will know how to match the input and output channel counts.
> To my understanding Clock and Streams descriptors are independent. And IN and OUT Streams descriptors are also independent. Which means that it could be possible to choose some streams configuration for the Input side, and another for the Output side. This is a point I'll have to investigate, how to make sure that a user won't be able to choose non consistent configurations.
What are your actual limitations?
Are input and output both going through a shared CODEC where the sample rates must match? I understand the ADAT channel limitations are based on sample rate, so those can't be exceeded.
If you try other USB Descriptors, let us know your results. You might want to restart this thread on the USB list at that point.
Brian
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