Re: (HAL) clock sources
Re: (HAL) clock sources
- Subject: Re: (HAL) clock sources
- From: Matthew Xavier Mora <email@hidden>
- Date: Wed, 2 Oct 2002 14:07:33 -0700
At 3:13 PM -0400 10/2/02, B.J. Buchalter wrote:
on 10/2/02 2:33 PM, Jeff Moore at email@hidden wrote:
I would not make that assumption. While it may seem odd at first
glance, but you don't want to tie your hands with respect to what
future hardware may be capable of.
On the other hand, a piece of hardware that did have individual clock
controls on a stream would be a pretty exotic piece of gear.
Well the obvious place would be a ASRC device that can clock its input and
output from different sources. So I can see a use -- but I guess that the
real question is if this is really a "clock source" in the CA sense -- or
does it really require a different type of control? I was under the
impression that by definition an Audio Engine has one shared clock -- if a
stream has a different clock (at least by the time it has hit the computer)
it should be in a different engine.
Opinions?
I think you are right B.J. I quote from the header doc:
" Within a single IOAudioEngine, all sample
* buffers must be the same size and be running at the same sample
rate. If different buffers/streams can
* be run at different rates, separate IOAudioEngines should be
used. The IOAudioEngine subclass must
* also call setSampleRate() at init time to indicate the starting
sample rate of the device.
*
"
mLAN poses an interesting dilemma here as there is no reason why an
mLAN device shouldn't be able to receive audio on multiple isoch
channels at different rates (I don't think the Mac OS 9 code allows
that). I guess in that case there would have to be an audio engine
created for each different sample rate coming in to the one device.
Matt
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