Switchable Bit-Plane Coding for High-Definition Advanced Audio Coding

Abstract

Scalable audio coding technique such as MPEG-4 Scalable Lossless coding (SLS) is a unified solution for demands in high-compression perceptual audio and high-quality lossless audio. It provides a fine-grain scalable extension of the well-known MPEG-4 Advanced Audio Coding (AAC) perceptual audio coder up to fully lossless reconstruction at word lengths and sampling rates typically used for high-resolution audio. Recently, the combination of SLS and AAC is renamed as “High Definition Advanced Audio Coding” (HD-AAC). It is observed that HD-AAC can be further improved at intermediate enhancement bitrate for many audio sequences when the core bitrate is low. Based on this observation, a Switchable Bit-Plane Coding (SBPC) is proposed in this paper. The SBPC consists of a normal BPC and a Prioritized BPC (PBPC). The corresponding optimal bit-plane coding method is switched into action according to the residual energy distribution in different frequency ranges. With the SBPC, the bit-plane coding for scalable audio can be implemented in a perceptually more efficient manner, and the perceptual quality of the audio under aforementioned scenario is much improved and stable.