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Re: kStereoMixerParam_PreAveragePower
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Re: kStereoMixerParam_PreAveragePower


  • Subject: Re: kStereoMixerParam_PreAveragePower
  • From: Chris Rogers <email@hidden>
  • Date: Thu, 17 Feb 2005 19:24:11 -0800

Title: Re: kStereoMixerParam_PreAveragePower
Sorry Dominic, I should have also asked if you're enabling metering.

You need to enable it on the mixerUnit with the kAudioUnitProperty_MeteringMode property.
A UInt32 value of 1 will turn it on.  The reason you need to explicitly enable it is because
it uses some of the CPU to compute the value (not a huge amount).

That should work better, good luck.
Chris Rogers
Core Audio
Apple Computer


Yes.  The audio is going through the mixer and is put into a ring buffer.  From there it is encoded and saved to a file.  All of the audio comes through mixed as expected.

The mixer is in an AUGraph.  I get the AudioUnit for the mixer node with:

AUGraphGetNodeInfo(mVOGraph, mixerNode, NULL, NULL, NULL, &mixerUnit);

Dominic Feira / Code Monkey / Ambrosia Software, Inc.

On Feb 17, 2005, at 3:05 PM, email@hidden wrote:
Dominic, when you are getting the parameter value are you currently
rendering and
supplying input sample frames which are non-zero?  The parameter value is meant
to give a measurement on the power of the input you're giving to the mixer.

Chris Rogers
Core Audio
Apple Computer
Hello.  I am trying to get kStereoMixerParam_PreAveragePower from a
stereo mixer.
I'm doing the following:


mLeftLevel = 0.0;
error = AudioUnitGetParameter(mixerUnit,
               kStereoMixerParam_PreAveragePower + 0,
          kAudioUnitScope_Input,
          0,
              &mLeftLevel);

Every time this runs I mLeftLevel comes back as -120.0.
AudioUnitGetParameter isn't returning an error.  Any idea?  Perhaps
I don't understand something.

Dominic Feira / Code Monkey / Ambrosia Software, Inc.

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 >Re: kStereoMixerParam_PreAveragePower (From: Dominic Feira <email@hidden>)

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