Re: (HAL) clock sources
Re: (HAL) clock sources
- Subject: Re: (HAL) clock sources
- From: Jeff Moore <email@hidden>
- Date: Wed, 2 Oct 2002 13:06:29 -0700
On Wednesday, October 2, 2002, at 12:13 PM, 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?
While I was writing that post, I was thinking of a piece of gear that I
once worked with in a post studio that resynchronizes audio, video for
printing to film. It had at least three timing sources it had to
reconcile: it's internal clock, the studio sync for the audio & video
being printed and the film being printed to.
When I thought a little bit, I tried to figure out how something like
that would present itself through the HAL. I still couldn't figure out
how that would resolve as anything other than one master control that
designated the master clock.
Still, I hesitate to say that you won't ever see more than one clock
source control for a device.
I think that the near future will have a much larger role for hardware
that is completely programmable (a box of DSPs or a computer over a
network, etc). Something like that would appear as some arbitrary
number of inputs and outputs with just about any imaginable software
running on it. I can easily see a situation where I have multiple
devices (with their own sets of clock sources) being facaded as a
single device with the synchronization handled on the CPU so it all
looks like one clock to an outside observer. In this case, I would
expect multiple clock sources, but only one engine.
That's a pretty exotic piece of gear, but within the realm of
speculation.
--
Jeff Moore
Core Audio
Apple
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