1. An apparatus for generating real-valued output audio samples, the apparatus comprising: memory that stores complex-valued input subband samples, real-valued demodulated samples, and the real-valued output audio samples; a phase shifter that shifts a phase of the complex-valued input subband samples by an amount equal to a previously added phase shift; and a complex-valued synthesis filter bank that generates the real-valued output audio samples in response to the complex-valued input subband samples, the real-valued demodulated samples, and prototype filter coefficients, wherein the complex-valued synthesis filter bank: shifts a first subset of the real-valued demodulated samples in the memory; multiplies the complex-valued input subband samples by a complex-valued exponential modulation matrix to generate complex-valued demodulated samples; stores the real part of the complex-valued demodulated samples in the memory as a second subset of the real-valued demodulated samples; extracts a third subset of the real-valued demodulated samples from the memory; multiplies the third subset of the real-valued demodulated samples by the prototype filter coefficients to generate windowed samples; combines the windowed samples to generate the real-valued output audio samples; and stores the real-valued output audio samples in the memory.