The design of a hybrid filter bank for the psychoacoustic model in ISO/MPEG phases 1, 2 audio encoder

The ISO/MPEG phases 1 and 2 audio compression are receiving a wide range of applications. In the MPEG encoding process, the psychoacoustic model exploits the audio irrelevancy which has the key role in achieving a high compression ratio without losing the audio quality. However, the Fourier transform (FT) which has been used by the two psychoacoustic models suggested in the draft standard requires a high computational complexity, and hence leads to high hardware and software cost for real-time applications. This paper presents a new design named the hybrid filter bank to replace the FT. The hybrid filter bank can be integrated with the psychoacoustic models and provides a much lower complexity than the FT. Also, this paper shows that the hybrid filter is more suitable for stereo coding and hence can provide a better quality for the intensity stereo coding, which is the key technology for the MPEG 1 to achieve a near transparent quality lower than 96×2 kbits for two stereo channels