Low power design of the perceptual noise substitution block for hardware AAC decoders

Perceptual Noise Substitution (PNS) is an important tool used in the Advanced Audio Coding (AAC) standard. The common PNS decoders use the Newton-Raphson method, which applies iterations to calculate the adjustment coefficient of the noise. This method is suitable for software AAC decoders, whereas for many portable consumer devices, hardware AAC decoders are preferred to reduce the power consumption. This paper proposes a low complexity PNS decoding algorithm based on partition and linear interpolation method. The proposed algorithm is optimized for hardware implementation, and consumes only 24-31% computations of the Newton-Raphson method, thus reduces the max clock frequency of the decoder and its power consumption. Also the proposed algorithm has nearly the same subjective perception with the Newton-Raphson method.