CLASSIFICATION OF FAST AND SLOW SIGNALS

摘要

Low bit rate audio coding such as BWE algorithm often encounters conflict goal of achieving high time resolution and high frequency resolution at the same time. In order to achieve best possible quality, input signal can be first classified into fast signal and slow signal. This invention focuses on classifying signal into fast signal and slow signal, based on at least one of the following parameters or a combination of the following parameters: spectral sharpness, temporal sharpness, pitch correlation (pitch gain), and/or spectral envelope variation. This classification information can help to choose different BWE algorithms, different coding algorithms, and different post-processing algorithms respectively for fast signal and slow signal.

主权项

1. A method of classifying an audio signal into a fast signal or a slow signal for audio coding, wherein the audio signal has a plurality of frames, the method comprising:
determining a parameter of each of the plurality of frames of the audio signal; and comparing the parameter with a pre-defined threshold as one of the determination elements to determine whether each of the plurality of frames should be classified into the fast signal or the slow signal, wherein the parameter is or is a function of spectral sharpness which is defined as a ratio between a maximum spectral magnitude and an average spectral magnitude on a spectral sub-band.