用非均匀时频变换提高音频编码器性能

Using NUTFT to Improve Audio Encoder

预回声对音频压缩编码器的性能影响很大。人们一般采用窗切换技术来降低其不利影响。窗切换中短窗提高了对暂态信号的时间分辨率,同时降低了对低频稳态信号的频率分辨率。设计了一种非均匀时频变换方法,它在保留了对信号低频平稳分量的频率分辨率的同时提高了对高频暂态分量的时间分辨率。最后用实验验证了方法的可行性和有效性。

The state of the art audio encoders use window switching technology to reduce or avoid pre-echoes encountered during encoding. However, the frequency resolution decreases when working with shorter block. Therefore we present a non-uniform time-frequency transform (NUTFT) to replace the ordinary time-frequency transform used in short block. The NUTFT can obtain high resolution in low frequency band and accurate location of high frequency components in time axis. The experiment result demonstrates the feasibility and efficiency.