Perceptual Optimization of the Frequency Selective Switch in Scalable Audio Coding

In a simple scalable audio coding scheme, there are usually two layers – a base layer and an enhancement layer. This paper presents a novel scheme with AMR-WB as base layer and AAC as enhancement layer. To optimally code the signal in the enhancement layer a frequency selective switch (FSS) control algorithm is described. The FSS determines whether the original signal or the residual of the original and base layer signals is sent to the enhancement layer in certain frequency bands. The proposed method introduces some advanced mechanism to the FSS and the quantization process as well as to minimizing the residual to achieve perceptually optimal result in the encoding process. These changes do not assume any modifications in the decoder.