Re: HALOutputUnit (Pt 1)
Re: HALOutputUnit (Pt 1)
- Subject: Re: HALOutputUnit (Pt 1)
- From: Robert Grant <email@hidden>
- Date: Tue, 13 Jan 2004 15:42:20 -0500
OK, I'm being really thick today - so apologies to everyone - but
what's the best way to determine whether to use the direct
AudioUnitRender or the SetInputCallback approach?
How do we determine programmatically that the input and output
device(s) being addressed by the HALOutputUnit are connected or not?
Thanks,
Robert.
On Jan 13, 2004, at 2:33 PM, William Stewart wrote:
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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