Patent ID: 8214207

Claim:
A method of quantizing a joint-channel-encoded audio signal, comprising: (a) obtaining an audio signal that includes a plurality of channels, with each channel including a block of samples; (b) segmenting the samples within each of a plurality of said blocks into quantization units; (c) jointly sum/difference encoding at least one pair of corresponding quantization units in different channels to produce a sum channel quantization unit and a difference channel quantization unit; (d) initializing quantization step sizes among the quantization units across the plurality of channels; (e) quantizing the samples in the quantization units using the assigned quantization step sizes; (f) calculating quantization errors for the quantization units; (g) based on the quantization errors, identifying a target quantization unit, from among the quantization units, for reduction of quantization step size; (h) determining whether the target quantization unit has been jointly sum/difference encoded with another quantization unit; (i) if the target quantization unit has not been jointly sum/difference encoded with another quantization unit, re-quantizing the target quantization unit using a decreased quantization step size; (j) if the target quantization unit has been jointly sum/difference encoded with another quantization unit, then: (i) designating the sum channel quantization unit as a target S/D quantization unit if the sum channel quantization unit has a greater quantization error than the difference channel quantization unit, (ii) designating the difference channel quantization unit as the target S/D channel quantization unit if the difference channel quantization unit has a greater quantization error than the sum channel quantization unit, and (iii) re-quantizing the target S/D channel quantization using a decreased quantization step size; (k) recalculating the quantization error for the target quantization unit; and (l) repeating steps (g)-(k) until a specified criterion is satisfied.