UpMixer = function(audiolet, outputChannels) {
    AudioletNode.call(this, audiolet, 1, 1);
    this.outputs[0].numberOfChannels = outputChannels;
}
Upmix an input to a constant number of output channels

**Inputs**

- Audio

**Outputs**

- Upmixed audio

@constructor
@extends AudioletNode
@param {Audiolet} audiolet The audiolet object.
@param {Number} outputChannels The number of output channels.