Re: kAudioUnitProperty_MaximumFramesPerSlice
Re: kAudioUnitProperty_MaximumFramesPerSlice
- Subject: Re: kAudioUnitProperty_MaximumFramesPerSlice
- From: Bill Stewart <email@hidden>
- Date: Mon, 8 Sep 2003 18:32:57 -0700
On Monday, September 8, 2003, at 04:51 PM, Marc Poirier wrote:
This is what it says in the AU API docs for
kAudioUnitProperty_MaximumFramesPerSlice:
"This property should be changed if an Audio Unit is going to be asked
to
render a particularly large buffer. This then allows the unit to
pre-allocate enough memory for any computations and output that it may
have to have buffers for (including the buffer that it can pass to a
RenderCallback). This avoids allocation in the render process, or a
failure in the render process, because the unit is asked to produce
more
data than it is able to at any given time."
Don't you think that's a little ambiguous and weakly defined? What is
"a
particularly large buffer"? Should the host always set this property
to
something before doing any rendering?
Probably - actually I think it is a good property to set WHENEVER you
are using an AU - as it can also save on allocation space as well. You
should also set this before initializing the AU's as that is where the
AU will do the allocations needed for rendering
I would tend to think that setting this property would be required
before
doing any processing, and then, if the host wants to render slices
larger
than the size that it set, it must of course set the property again.
That's what I would think would be the expectations for this property,
but
the docs leave things really wide open to interpretation. Could this
please be clarified and more specifically defined? I've already now
encountered 2 different AU hosts that don't set this property ever,
causing all AUs to not work at all when you have audio hardware buffer
sizes configured above 1156 in those apps, so I think that maybe is a
good
sign that this need to be defined clearly and specifically and
emphasized
in the docs.
Yes - point taken.
Bill
Thanks,
Marc
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