Re: Scheduling ramp parameters
Re: Scheduling ramp parameters
- Subject: Re: Scheduling ramp parameters
- From: Bjorn Roche <email@hidden>
- Date: Thu, 13 Jul 2006 09:52:40 -0400 (EDT)
On Wed, 12 Jul 2006, William Stewart wrote:
On 11/07/2006, at 1:36 PM, Bjorn Roche wrote:
Hey all,
I have an AU host app that works fine with non-ramp-able parameters.
However, I recently tried my first plug-in that actually supports ramp-able
parameters, Audio Ease's Altiverb 5 (anybody know any more?). When I try
scheduling parameters with that, it either ignores the transition or
produces a loud noise. In Ableton Live it works fine. I have two suspicions
about why this might be:
1. Instead of lumping all my scheduling together and making one call to
AudioUnitScheduleParameters(),
Yes, this is expected
I am making a number of calls with only one AudioUnitParameterEvent per
call, like this:
AudioUnitScheduleParameters( audioUnit, &ape, 1 );
this is ok too.
Thanks, William.
Will the audio units themselves see any difference between these types of
calls, or does the AU API convert both
for 1 to n
AudioUnitScheduleParameters( audioUnit, &ape, 1 );
and
AudioUnitScheduleParameters( audioUnit, &apes, n );
to the same thing as far as the Audio Unit is concerned? In other words,
is there any way for the Audio Unit to know if you made one call with all
the data or many calls with just a piece of the data? I ask because this
is the only thing I can see that I may be doing differently from other
software and if there's one thing I've learned about Audio Units it that
if you do things differently, some popular audio unit out there will
break.
2. I am scheduling the parameters right before my own render call, rather
than in the pre-render notification. It has been suggested on this list
that the best place to schedule parameters is in the prerender
notification, but I don't see how it could be an issue as long as I do it
right before the render and from within the same thread.
If the AU does something to clear this state between your call to
AudioUnitRender and its call to your pre-render, then this doesn't work of
course. You should also bare in mind that the AU's only thread context for
doing work is the call the host makes to AudioUnitRender. The suggested
guideline is to schedule these activities in the pre-render notification for
this reasons.
I put the scheduling code in the pre-render notification. My code isn't
any messier, which is nice, but I still have a problem with that one AU.
thanks again for your help!
bjorn
-------------
Bjorn Roche
Check out my CD Mastering Software
for Mac OS X : http://www.xowave.com
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