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为了更好地满足音频编码中时频映射的技术要求,基于频变调制重叠变换(FV-MLT),推导出更具一般性的频变扩展重叠变换(FV-ELT),从而构造了一类具有可变时频分辨率特性的滤波器组。它既可为瞬态音频信号提供灵活的时频映射,又保证稳态信号时有很高的频率分辨率。理论分析结果表明FV-ELT比MLT和FV-MLT有更高的变换增益,以8子带为例的仿真结果,也进一步验证FV-ELT提供了更好的时频分析特性。因此FV-ELT是非常适于音频编码时频分析的一类滤波器组,能够有效提高编码效率。
In order to meet the technical requirements of time-frequency mapping in audio coding, a more generalized FV-ELT (Frequency Change Extended Transform) is derived based on FV-MLT. Filter banks with variable time-frequency resolution. It not only provides a flexible time-frequency mapping of transient audio signals, but also guarantees a high frequency resolution in steady-state signals. The theoretical analysis shows that FV-ELT has higher conversion gain than MLT and FV-MLT. The simulation results using 8-band as an example further prove that FV-ELT provides better time-frequency analysis. Therefore, FV-ELT is very suitable for audio coding time-frequency analysis of a class of filter banks, can effectively improve the coding efficiency.