Re: AudioUnitScheduleParameters: ramped kMultiChannelMixerParam_Volume
Re: AudioUnitScheduleParameters: ramped kMultiChannelMixerParam_Volume
- Subject: Re: AudioUnitScheduleParameters: ramped kMultiChannelMixerParam_Volume
- From: uɐıʇəqɐz pnoqɥɒɯ <email@hidden>
- Date: Mon, 14 Jun 2010 13:35:22 -0700
On Jun 14, 2010, at 12:46 PM, William Stewart wrote:
you are misunderstanding how this works, it doesn't work like this.
There are some notes about how ScheduleParameters work in the headers, but basically it is about setting parameter values on a given buffer. It is not a generic "schedule ahead" feature.
That's too bad! Sorry, wishful thinking on my part.
For that, you would need MusicSequence (on desktop, see <AudioToolbox/MusicPlayer.h>
Not on the iPhone, correct?
Also, you need to first check to see if a given parameter supports ramping (in the parameter info), otherwise the behaviour is undefined. The implementation won't return an error at the time the event is scheduled, as it doesn't know what the implementation class will do with the parameter event. This is a "driver take care" feature.
I couldn't find enough documentation or samples on this, so I presumed way too much. It all started with this quote: AudioUnitSetParameter Sets the value of an audio unit parameter.
Since I was using AudioUnitSetParameter from within my render or renderNotification to create a fade-out, I figured that I could intercahangebaly use AuduiUnitScheduleParameters, based on the above.
and then this:
With a single call to this function, you can schedule multiple parameter events. All the events apply only to the current audio unit render call; the events are scheduled as a part of the pre-render notification callback.
When scheduling a ramped parameter, the ramp is scheduled each audio unit render for the duration of the ramp. Each schedule of the the new audio unit render specifies the progress of the ramp.
Bill, I have to thank you and your team, including Murray and Edward for being so helpful last week at WWDC. Truthfully, the time I spent with those gentlemen was well worth the conference fee!
-mahboud |
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