Audio transform coding using pitch correction

Abstract

A processed representation of an audio signal having a sequence of frames is generated by sampling the audio signal within a first and a second frame of the sequence of frames, the second frame following the first frame, the sampling using information on a pitch contour of the first and the second frame to derive a first sampled representation. The audio signal is sampled within the second and the third frame, the third frame following the second frame in the sequence of frames. The sampling uses the information on the pitch contour of the second frame and information on a pitch contour of the third frame to derive a second sampled representation. A first scaling window is derived for the first sampled representation and a second scaling window is derived for the second sampled representation, the scaling windows depending on the samplings applied to derive the first sampled representations or the second sampled representation.

Description

technical field

[0001] Various embodiments of the invention relate to an audio processor that uses pitch-dependent sampling and resampling of a signal to generate a processed representation of a framed audio signal. Background technique

[0002] Lapped transforms based on cosine or sine modulation, corresponding to modulated filter banks, are often used in source coding applications due to their energy-compact properties. That is, for harmonics with a constant fundamental frequency (pitch), the transformation concentrates the signal energy into a smaller number of spectral components (subbands), enabling an efficient signal representation. In general, the pitch of a signal should be understood as the lowest dominant frequency that can be distinguished from the signal spectrum. In common speech models, pitch is the frequency of an excitation signal modulated by the human voice. If there is only a single fundamental frequency, the spectrum is extremely simple, comprising onl...