iOS - Audiounit volume balance between channel

Question

I created an AUGraph to play music from iTunes library. I added mixer unit and effect unit to the AUGraph in the following order

FilePlayerUnit->MixerUnit->EffectUnit->OutputUnit

I am trying to change the volume balance between left and right channel. For example by using a UISlider user should be able change the frequency in a particular channel.

Is it possible to do this without modifying my current AUGraph based player with FilePlayer Unit that plays music files from local storage?

score 0 · Accepted Answer · answered Nov 01 '14 at 15:41

0

You just need to set those properties on the input scope of the desired channel(element).

float pan = 0;  //  -1  -> 1
AudioUnitSetParameter (MixerUnit, kMultiChannelMixerParam_Pan, kAudioUnitScope_Input, channel, pan, 0);

Got the above answer in the Core Audio mailing list. Thank you Dave O'Neill.

answered Nov 01 '14 at 15:41

Clement Prem

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When I tried to set pan value, then I am getting below error: *** AudioUnitSetParameter (Pan) error: 'fmt?' – Nirmalsinh Rathod Mar 22 '15 at 08:49
can you post your code? Are you setting the value in the Mixer audio unit? – Clement Prem Mar 22 '15 at 10:02
OSStatus resultPan = AudioUnitSetParameter ( mixerUnit, kMultiChannelMixerParam_Pan, kAudioUnitScope_Input, 0, -1, 0 ); if (noErr != resultPan) {[self printErrorMessage: @"AudioUnitSetParameter (Pan)" withStatus: resultPan]; return;} – Nirmalsinh Rathod Mar 23 '15 at 04:23
how do you create "mixerUnit", are you correctly setting audio component type(kAudioUnitType_Mixer) & subtype (kAudioUnitSubType_MultiChannelMixer) – Clement Prem Mar 23 '15 at 04:54
Yup, I have used kAudioUnitType_Mixer and kAudioUnitSubType_MultiChannelMixer – Nirmalsinh Rathod Mar 23 '15 at 05:14

iOS - Audiounit volume balance between channel

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