Effective high frequency regeneration based on sinusoidal modeling for MPEG-4 HE-AAC
A novel approach is proposed for effective high frequency regeneration in audio coding, which is based on a sinusoids plus noise model. It assumes a standard high efficiency advanced audio coding (HE-AAC) encoder, and modifies the decoder to exploit all available information in estimating the model parameters. From the lower band reconstruction of core AAC, frequency parameters of the high band sinusoids are estimated. Side information about spectral energy and the regenerated high band of standard HE-AAC are employed in estimating the magnitude parameters of the high band sinusoids as well as noise model parameters. The gains achieved by the proposed technique, over conventional HE-AAC, are demonstrated by subjective quality tests that were carried out on audio signals with significant harmonics in the high band.