Providing a time warp activation signal and encoding an audio signal therewith

摘要

Abstract An audio encoder for generating an encoded audio signal, comprising: an audio signal analyzer for analyzing, whether a time frame of the audio signal has a harmonic or speech 5 characteristic; a window function controller for selecting a window function depending on a harmonic or speech characteristic of the audio signal; a windower for windowing the audio signal using the selected window function to obtain a windowed frame; and a processor for further processing the windowed frame to obtain the encoded audio signal; wherein the window function controller comprises a transient detector for 10 detecting a transient, wherein the window function controller is configured for switching from a window function for a long block to a window function for a short block, when a transient is detected and a harmonic or speech characteristic is not found by the audio signal analyzer, and for not switching to the window function for the short block, when a transient is detected and a harmonic or speech characteristic is found by the audio signal 15 analyzer; and wherein the window function controller is configured for switching to a window function being longer than the window function for a short block and adapted to obtain a shorter left-sided overlap length with a previous window than the window function for a long block, when a transient is detected and the signal has a harmonic or speech characteristic, such that the window function adapted to obtain a shorter overlap length is 20 used for windowing a speech onset or an onset of a harmonic signal. Figure 5a -o o Ln C