Re: Audio Unit (debug) output parameters
Re: Audio Unit (debug) output parameters
- Subject: Re: Audio Unit (debug) output parameters
- From: William Stewart <email@hidden>
- Date: Wed, 24 Jan 2007 14:07:08 -0800
This isn't quite correct.
To get the meter you should do two things:
(1) Declare the parameter as read only - the type can be anything
except a boolean - for instance we use dB in the one you mentioned
(2) Also declare the parameter to have a type of
kAudioUnitParameterFlag_MeterReadOnly
Both of the generic views we provide will then treat the parameter as
a read only meter parameter and provide a meter API.
The view then sets up a timer for this param to draw at some
frequency - and as it wakes up it will ask your AU to provide the
value for this parameter - you can either calculate it then, or
returned a value that you might have calculated in the Render function.
This is why we added the meter flag for a param, so we know which
params we need to treat this way. One thing that I would NOT do for
this kind of parameter is send a notification that the value has
changed - if you are metering audio, then this is changing very often
- far more often than a UI needs or can draw it.
Bill
On 09/01/2007, at 8:42 AM, Stefan Gretscher wrote:
Hi Frank,
Am 09.01.2007 um 16:42 schrieb Frank Schoep:
How would I go about updating the value from within my Audio Unit
so that the host application knows to redraw the control?
In order for the host or any views attached to the AU to pick up
changes an AU might apply to its parameters, they must be notified
using AudioUnitEvents as described in this technote:
http://developer.apple.com/technotes/tn2002/tn2104.html
This is true both for read-only (displays) and for read+write
(automatable) parameters.
Best,
Stefan
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