Shaping coding noise with frequency-domain companding

We present in this paper an approach to shape the coding noise in speech and audio coders, which is based on pre-processing and post-processing, In this approach, called Spectral Amplitude Warping (SAW), the coding noise is shaped by applying companding to the amplitudes of the Fourier spectrum prior to and after encoding. An important advantage of this method is that signal adaptive noise shaping is accomplished by using a constant companding function, thus requiring no additional information to be sent to the decoder.