Harmonic Transposition in an Audio Coding Method and System

摘要

The present invention relates to transposing signals in time and/or frequency and in particular to coding of audio signals. More particular, the present invention relates to high frequency reconstruction (HFR) methods including a frequency domain harmonic transposer. A method and system for generating a transposed output signal from an input signal using a transposition factor T is described. The system comprises an analysis window of length La, extracting a frame of the input signal, and an analysis transformation unit of order M transforming the samples into M complex coefficients. M is a function of the transposition factor T. The system further comprises a nonlinear processing unit altering the phase of the complex coefficients by using the transposition factor T, a synthesis transformation unit of order M transforming the altered coefficients into M altered samples, and a synthesis window of length Ls, generating a frame of the output signal.

主权项

1. A system for transposing an input audio signal by a transposition factor T, the system comprising:
a parser for extracting a frame of L time-domain samples of the input signal using an analysis window of length L, a transformer for converting the L time-domain samples into M complex frequency-domain coefficients; a nonlinear processing unit for altering a phase of the frequency-domain complex coefficients using the transposition factor T; a transformer for converting the altered frequency-domain coefficients into M altered time-domain samples; and a generator for creating a frame of L time-domain output samples from the M altered time-domain samples using a synthesis window; wherein M=F*L, with F being a frequency domain oversampling factor which is based on the transposition factor T.