A Hybrid Warped Linear Prediction (WLP) AAC Audio Coding Algorithm

We propose a hybrid warped linear prediction (WLP) AAC audio coding algorithm. The proposed algorithm employs a warped linear prediction (WLP) processor to construct a perceptual pre- and post-filter for the MPEG-4 AAC. The WLP residual is applied to the MDCT filterbank and the signal-to-mask ratio (SMR) of the corresponding block is modified to set a masking threshold for the WLP residuals. In the decoder, the reconstructed residual signal is passed to a modified WLP synthesis filter to restore the audio signal. Subjective tests show that the proposed audio codec operating at 50kbps has comparable perceptual quality to the conventional MPEG-4 AAC operating at the 58kbps.