Bug 14315 - The Multichannel Mixer AudioUnit seems to be limited to maximum 9 input bus
Summary: The Multichannel Mixer AudioUnit seems to be limited to maximum 9 input bus
Alias: None
Product: iOS
Classification: Xamarin
Component: XI runtime ()
Version: 6.4.4
Hardware: PC Windows
: --- normal
Target Milestone: Untriaged
Assignee: Marek Safar
Depends on:
Reported: 2013-08-29 02:38 UTC by pierre
Modified: 2013-09-02 07:47 UTC (History)
3 users (show)

Is this bug a regression?: ---
Last known good build:

sample of the problem (6.39 MB, application/octet-stream)
2013-09-01 22:24 UTC, pierre

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Description pierre 2013-08-29 02:38:06 UTC
With the native MultiChannelMixer sample from apple I can go up to 200 input channels with the iphone simulator (methods AUGraphSetNodeInputCallback and AudiUnitSetProperty succeed).

With MonoTouch, all the calls to AudioUnit.SetRenderCallback, AudioUnit.SetParameters, ... systematically fails returning error "InvalidElement" when the input bus index is higher than 8.

This problem prevent me from mixing more than 8 musics together.
Comment 1 Marek Safar 2013-08-30 07:03:00 UTC
AUGraphSetNodeInputCallback is not yet available in our bindings, do you have a sample which exercises this api?
Comment 2 pierre 2013-09-01 22:24:47 UTC
Created attachment 4768 [details]
sample of the problem

I added two samples:
 - one derived from the apple 'iPhoneMultichannelMixerTest' sample. Important code is located in 'MultichannelMixerController.mm'file and initializeAUGraph function.
 - one from derived the xamarin 'AUSoundTriggeredPlayingSoundMemoryBased'. Important code is located in 'ExtAudioBufferPlayer.cs' file and 'prepareAudioUnit' function.
Comment 3 Marek Safar 2013-09-02 07:47:25 UTC
8 happens to be default for the mixer. You need to call SetElementCount method to set the actual number of bus elements on the audio unit.