Re: HALOutputUnit (Pt 1)
Re: HALOutputUnit (Pt 1)
- Subject: Re: HALOutputUnit (Pt 1)
- From: William Stewart <email@hidden>
- Date: Tue, 13 Jan 2004 11:33:24 -0800
On 13/01/2004, at 6:03 AM, Robert Grant wrote:
Just a final clarification - would it be OK to use the
SetInputCallback approach for reading audio from all HAL devices (both
uni and bi-directional)? I don't think it would but I'm just trying to
see if there's a "once size fits all" approach?
Yes - its a "one size fits all" approach. However, if you're dealing
with a device with in as well as out streams, you are already going to
be called for output - so at that point you should just get the input
data...
Bill
Thanks,
Robert.
On Jan 12, 2004, at 11:04 PM, James Coker wrote:
Does this imply that all, or almost all USB audio devices will have
this setup?
Jim
On Jan 12, 2004, at 7:33 PM, Jeff Moore wrote:
Yes this is true. The USB spec doesn't require that the input side
of a device be clocked the same as the output side. They can even be
running at different sample rates and still be adhering to the spec.
From the HAL's point of view, the two sides of the device represent
two separate clock sources. Therefore the HAL publishes them as
separate devices through the API.
On Jan 12, 2004, at 5:54 PM, Robert Grant wrote:
Thanks a lot Bill - that clarifies things tremendously. And I think
I now know why Audio In from the HALOutputUnit was not working for
me a while back - I'm using a USB Audio I/O device and I guess that
shows up as two separate Audio Devices?
Robert.
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