Method and apparatus for generating an enhancement layer within a multiple-channel audio coding system

An apparatus operable to code a multiple channel audio signal, comprising:

• an encoder that receives a multiple channel audio signal that comprises a plurality of audio signals and codes the multiple channel audio signal to generate a coded audio signal;
• a scaling unit of an enhancement layer encoder that scales the coded audio signal with a plurality of gain values to generate a plurality of candidate coded audio signals, wherein at least one of the candidate coded audio signals is scaled;
• a balance factor generator that generates a balance factor having a plurality of balance factor components each associated with an audio signal of the plurality of audio signals of the multiple channel audio signal;
• wherein the scaling unit and the balance factor generator generate an estimate of the multiple channel audio signal based on the balance factor and the at least one scaled coded audio signal of the plurality of candidate coded audio signals;
• a gain selector of the enhancement layer encoder that evaluates a distortion value based on the estimate of the multiple channel audio signal and the multiple channel audio signal to determine a representation of an optimal gain value of the plurality of gain values;
• a transmitter that transmits the representation of the optimal gain value for at least one of transmission and storage.

A method for coding a multiple channel audio signal, comprising:

• receiving a multiple channel audio signal that comprises a plurality of audio signals;
• coding the multiple channel audio signal to generate a coded audio signal;
• generating a balance factor having a plurality of balance factor components each associated with an audio signal of the plurality of audio signals of the multiple channel audio signal;
• determining a gain value to be applied to the coded audio signal to generate an estimate of the multiple channel audio signal based on the balance factor and the multiple channel audio signal, wherein the gain value is configured to minimize a distortion value between the multiple channel audio signal and the estimate of the multiple channel audio signal;
• and
• outputting a representation of the gain value for at least one of transmission and storage.