Transform Coding Based on Source Filter Model in the MDCT Domain

Abstract

State‐of‐the‐art voice codecs have been developed to extend the input bandwidth to enhance quality while maintaining interoperability with a legacy codec. Most of them employ a modified discrete cosine transform (MDCT) for coding their extended band. We propose a source filter model‐based coding algorithm of MDCT spectral coefficients, apply it to the ITU‐T G.711.1 super wideband (SWB) extension codec, and subjectively test it to validate the model. A subjective test shows a better quality over the standardized SWB codec.