Re: AudioUnitScheduleParameters
Re: AudioUnitScheduleParameters
- Subject: Re: AudioUnitScheduleParameters
- From: Ev <email@hidden>
- Date: Mon, 11 Apr 2005 14:08:03 -0500
On Apr 11, 2005, at 1:41 PM, William Stewart wrote:
Nope - in fact you may lose scheduling events for ramping if you
schedule stuff in Post Render...
OK, I looked into the RenderNotify call, and it seems as though it will
call before the *audio unit* renders, which is assumedly after the
*callback render*, so it might be a no-brainer, my 'play location' will
already be current.
The MusicSequence API's also support scheduling ramps - all you need
is a track with:
MusicTrackSetProperty with kSequenceTrackProperty_AutomatedParameters
and a UInt32 set to 1 (tells the sequence engine to treat this track
in this way)..
Then it looks at parameter events in that track as pairs:
The first param event - start of the first ramp
The second param event - end of the first ramp
The third param event - start of the second ramp
The fourth param event - end of the second ramp, etc...
The two pairs must of course have the same paramID - if you need
overlapping ramps for different params, then you will need to put them
in different tracks.
And I'm assuming these ramps are linear, is that the case?
That's the tough issue with curves; how much resolution between steps
or ramps do you give it before it becomes unwieldy in terms of events
vs sonic stair-stepping? Ramping at least makes that decision a lot
easier - and one graph buffer size is actually a pretty good window in
terms of timing - i'd imagine that if you wrote two MusicSequence track
parameter events that were ramps (as you demonstrate above), they
eventually get broken down to ramps at the buffer size level anyway...
I'm probably just coding the same thing that the MusicSequence API is
calculating.
Thanks for your help, Bill - you've given me a lot to go on. This
should work fantastically.
Ev
Technical Knowledge Officer
Head Programmer/Designer
Audiofile Engineering
http://www.audiofile-engineering.com/
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