Adaptive prediction order scheme for AMR-WB+

In this paper, we present an adaptive linear prediction order scheme - a simple and effective method to facilitate variable rate coding. We have applied it to the Extended Adaptive Multi-Rate Wideband (AMR-WB+), a state-of-the-art generic speech and audio coder with fixed-length coding designed for wireless transmission. By introducing this scheme into the codec, bit rate can be reduced with a negligible degradation of the quality. The order of linear prediction is adapted based on the audio content, and can be determined by a closed-loop or an open-loop optimal order selection module. The resulted audio quality is examined by average segmental SNR and Perceptual Evaluation of Audio Quality (PEAQ) measure. For this evaluation, speech, music and mixed content audio signals are used. The result proves the effectiveness of this method.