1. Apparatus for digitally encoding an input audio signal, for storage or transmission, comprising: pitch detection means for determining at least a dominant time-domain periodicity in the input signal; means for generating a prediction signal based on the dominant time domain periodicity of the input signal; first discrete frequency domain transform means for generating a frequency domain representation of the input signal; second discrete frequency domain transform means for generating a frequency domain representation of the prediction signal; means to subtract at least a portion of the frequency domain representation of the prediction signal from the frequency domain representation of the input signal to generate an error signal; and means to generate an output signal from the error signal and parameters defining the prediction signal.