Re: Does anyone get an AudioDevice that has both input and output channels? (question is related to software play through)
Re: Does anyone get an AudioDevice that has both input and output channels? (question is related to software play through)
- Subject: Re: Does anyone get an AudioDevice that has both input and output channels? (question is related to software play through)
- From: Karl MacMillan <email@hidden>
- Date: Wed, 18 Jul 2001 17:54:28 -0400 (EDT)
On Wed, 18 Jul 2001, Jeff Moore wrote:
>
on 7/18/01 2:31 PM, Karl MacMillan <email@hidden> wrote:
>
>
> Are there any garuntees about how the 2 IOProcs will be called (i.e. that
>
> they will be called one right after one another)?
>
>
No.
>
>
> Otherwise buffering is going to introduce extra latencies.
>
>
This is true, but this is the only way to do software play thru from one
>
arbitrary device to another arbitrary device no matter what. Most devices,
>
especially USB devices, have either input or output, but not both so you
>
have to be prepared in any case.
>
Playing from one device to another seems likely to fail to me if those two
devices do not have a common clock source (which would be the case for
most consumer cards). This is not an issue that can be solved by
buffering because it is likely that this cards will run at different clock
rates entirely (although they will be close) rather than just clock
jitter. Do you guys have a solution to this?
Also, I hate to see the introduction of this extra buffering - this api
looks very promising in terms of latency (and the output only tests I have
done seem to work well) but unless 1 IOProc can deliver both input and
output I think this will always fall behind something like ASIO. So
again, will the built-in audio device driver be fixed?
Karl
>
--
>
>
Jeff Moore
>
Core Audio
>
Apple
>
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>
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>
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_____________________________________________________
| Karl W. MacMillan |
| Computer Music Department |
| Peabody Institute of the Johns Hopkins University |
| email@hidden |
| mambo.peabody.jhu.edu/~karlmac |
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