Apple

Hi Dave,

Thanks for your response. We call that API before connecting anything to the mixer:

err = AudioUnitSetProperty(mMixer, kAudioUnitProperty_ElementCount, kAudioUnitScope_Input, 0, &numbuses, sizeof(numbuses));

if (err) {

NSLog(@"Error - initializeAUGraph - AudioUnitSetProperty - kAudioUnitProperty_ElementCount - error:%d", err);

return false;

}

We are compiling with target SDK 10.6 (I'm not sure that makes any difference but we need backward compatibility).

It's interesting you mentioned you've used it with 100 for a test and that worked. Do you happen to have that test handy so I can give it a try?

Thanks

Marcelo

From: Dave O'Neill <email@hidden>
Sent: Monday, March 7, 2016 3:43 PM
To: Marcelo Birnbach
Cc: email@hidden
Subject: Re: kAudioUnitType_Mixer limit?

For kAudioUnitSubType_MultiChannelMixer you have to set the channel count before using any more than eight. I've used 100 for a test and it was smooth sailing.

UInt32 channelCount = 16;

AudioUnitSetProperty(mixerUnit , kAudioUnitProperty_ElementCount, kAudioUnitScope_Input, 0, &channelCount, sizeof(channelCount));

On Mon, Mar 7, 2016 at 12:31 PM, Marcelo Birnbach <email@hidden> wrote:

Hi all,

I wonder if there's any limit to the number of input buses a kAudioUnitType_Mixer can use. I empirically found that buses higher than ~8 are discarded. That means that I can mix up to 7 inputs but the 8th and higher are silent in the output mix.

I tried with kAudioUnitSubType_MultiChannelMixer, kAudioUnitSubType_StereoMixer and kAudioUnitSubType_3DMixer sub-types. All input buses are set to mono 44100hz and the mixer output is stereo.

I got the same behavior regardless whether I connected other nodes to the mixer input buses or using render input callbacks.

We are calling setting setting the kAudioUnitProperty_ElementCount property with the right value (e.g. 11 buses).

Does anyone have an idea of what's going on? I was thinking about using N number of mixers and connecting them to a master mix but that sounds like a hack to me and I'd love to understand what's going on first.

Thanks

Marcelo

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References:
	>kAudioUnitType_Mixer limit? (From: Marcelo Birnbach <email@hidden>)
	>Re: kAudioUnitType_Mixer limit? (From: "Dave O'Neill" <email@hidden>)