AudioSession input from bluetooth output to line out or speaker

Question

Once an audio session has been set up the following code allows bluetooth input.

UInt32 allowBluetoothInput = 1;
AudioSessionSetProperty (kAudioSessionProperty_OverrideCategoryEnableBluetoothInput, sizeof (allowBluetoothInput), &allowBluetoothInput);

This code looks like it only allows bluetooth input however this code also routes the audio output to the bluetooth device (in the case of a bluetooth headset). I would like to route the audio output out of the line out or speaker when the input is coming from a bluetooth device. I just want to get audio input from a bluetooth device, I do not want to output audio via bluetooth.

Is this behaviour possible?

Answer 1

as of iOS 5 this behaviour is not possible, quoting apple technical support

Bluetooth devices are not "Jacked In" devices and therefore any other audio routing must be user picked and cannot be changed in code. To do this, you can use the functionality of the MPVolumeView which will have an extra routing widget viewable allowing the user to specify the routing of the output.

There's a older thread on the Core Audio mailing list regarding this functionality but behavior hasn't changed:

http://lists.apple.com/archives/coreaudio-api/2009/Oct/msg00030.html

MPVolumeView reference:

http://developer.apple.com/library/ios/#documentation/mediaplayer/reference/MPVolumeView_Class/Reference/Reference.html

However the MPVolumeView does not allow you to route the input and output independently.