Re: Audio Units and OpenCL?
Re: Audio Units and OpenCL?
- Subject: Re: Audio Units and OpenCL?
- From: Mike Lemmon <email@hidden>
- Date: Wed, 9 Sep 2009 11:51:29 -0700
Pretty interesting. Just how bad are OpenCL and GCD in this regard --
are there any statistics out there? I'd be interested to see whether
the latency is consistently high or just occasionally hiccups or what.
And there seems to be conflicting reports on multi-threading. A multi-
threaded Audio Unit: kosher or not? If it's alright, what about
creating a second thread and running the OpenCL code from there?
On 9/09/2009, at 09:43 AM, James McCartney wrote:
Almost all research in the parallel/multiprocessing/concurrency
communities is about maximizing throughput and utilization and there
is not even very much awareness of real time issues like minimizing
or bounding latency except among the real-time financial folks. So
most known architectures and techniques that are published in the
literature are not going to be beneficial for audio. As to awareness
within Apple of these issues, we in CoreAudio and in some other
media groups are aware and are always doing what we can to make
others groups aware: fast is not real time. slow is not necessarily
not real time. fast enough with reliable bounds on latency is real
time.
On Sep 9, 2009, at 8:42 AM, Richard Dobson wrote:
So, is there anything in this much-hyped technology that is
actually a benefit to audio developers, to enable them to do what
has not been done before (like, use all "available" cores for audio
processing)?
If not, it is another nail in the coffin of the general-purpose
computer as an audio processor, and the industry will move even
further towards custom hardware in which they can implement
whatever parallel processing they need, and have full control over
it.
Also, presumably an older d/c iMac with the Radeon1600 chipset
cannot run openCL code, so can it at least degrade gracefully to at
least build and run on such a machine?
On an 8-core Mac Pro, how many cores will we see Logic Pro using?
This all rather reinforces speculations I have made that in the
headlong rush to concurrent multi-core nirvana, audio will be left
behind, or simply ignored/underestimated as a relevant activity.
Richard Dobson
Markus Fritze wrote:
Ehm, you know that GCD is running at the main thread level? Which
can be blocked by UI operations, etc. That doesn't seem like a
wise choice for real-time processing. OpenCL also doesn't have a
threading mode, so you tasks will be shared among all the others
and your latency becomes unpredictable.
Markus
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