Re: Scheduling AU Parameter Changes (was Re: Number of frames in Render())
Re: Scheduling AU Parameter Changes (was Re: Number of frames in Render())
- Subject: Re: Scheduling AU Parameter Changes (was Re: Number of frames in Render())
- From: William Stewart <email@hidden>
- Date: Wed, 19 Jul 2006 17:47:24 -0700
You still have to send a notifiction that the param changed.
AUParameterSet is not an AU API - rather it is an <AudioToolbox/
AudioUnitUtilities.h> API (AudioEvent...) - it does 2 things:
- calls AudioUnitSetParameter
- calls AUEventNotify
So, if you're calling AudioUnitSetParameter (or ScheduleParameters),
then you can also call the Notify API in that header file
As for the buffer offset - I think most AUs ignore this (its actually
a buffer offset passed to AudioUnitSetParameter) - whereas with the
Schedule API its explicitly expected that it will be honoured...
Bill
On 19/07/2006, at 5:40 PM, Jeremy Sagan wrote:
Hello Bill,
Previously I was using AUParameterSet and I tried switching to this
sample accurate method using AudioUnitScheduleParameters and while
it works it seems like (at least some) plug-ins do not update there
display properly after receiving these messages. I then discovered
that AUParameterSet has a buffer offset field. Would that not give
me the same results and with far fewer changes to my code?
Thanks again,
Jeremy
On Jul 18, 2006, at 7:00 PM, William Stewart wrote:
There's no way to actually tell.
We test this as part of the tests in auval, so if the AU passes
validation it at least accepts these scheduled params.
AUBase has support for an implmentation that just slices up the
render call internally - you could of course do alot more here
(and the AU can discern more about the context of these scheduled
changes of course). But, I don't know how many AUs explicitly take
care of this themselves. All of Apple's effects will.
Bill
On 18/07/2006, at 2:14 PM, Jeremy Sagan wrote:
Very cool. I don't know how I missed that.
Do you know if all AU plug-ins support the immediate scheduled
parameters?
Thanks,
Jeremy
On Jul 18, 2006, at 4:04 PM, William Stewart wrote:
Ideally, you could always pull the AU for the same amount of
data, and use the ScheduleParams API to schedule intra-buffer
parameter changes
On 17/07/2006, at 8:17 PM, Jeremy Sagan wrote:
Hello Doug,
On Jul 17, 2006, at 8:42 PM, Doug Wyatt wrote:
Some hosts implement sample-accurate automation by rendering
the samples before and after a parameter change with separate
render calls (this is inefficient and it's better to let the
plug-in handle this, but nothing in the spec forbids it).
How do you "let the plug-in handle this" with the current state
of AU?
Jeremy Sagan
Sagan Technology
www.sagantech.biz
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