Lossless coding of audio spectral coefficients using selective bitplane coding

In this paper, a novel lossless coding method of spectral coefficients for audio codec is proposed. Conventional lossless coder directly codes the spectral coefficients based on their statistical characteristics, but does not provide the high coding efficiency due to its simple structure. To solve this limitation, a new lossless coding scheme consisting of bitplane coding and runlength coding is proposed. In the proposed scheme, the spectral coefficients are first transformed by bitplane coding to a bit stream, and the resulting bit stream is coded by runlength and finally entropy coded. In addition, the coding performance is further increased by applying the proposed bitplane coding selectively to spectral bands. The performance of proposed coding method is measured in terms of the ideal number of bits based on the entropy, which shows that the proposed method has better performance than the conventional lossless coder in AAC audio codec.