A speech coder post-processor controlled by side-information

Speech coders provide high speech quality at low rates. However they perform poorly when encoding non-speech signals. This paper proposes a new enhancement algorithm requiring minimum side information to reduce the effect of this shortcoming. The enhancement algorithm consists of post-processing the speech decoder output in the spectral domain. Specifically, some frequency components are reduced or forced to zero when the corresponding frequency content is poorly described by the speech coder. The choice of modifying spectral components is determined at the encoder, thus requiring us to transmit the decision information. Experiments combining the AMR-WB speech codec and the proposed audio enhancement show that the quality for music signals is improved significantly while not affecting the quality for speech inputs.