Warped linear predictive coding

Warped Linear Predictive Coding (Warped LPC or WLPC) is a variant of Linear predictive coding in which the spectral representation of the system is modified, for example by replacing the unit delays used in an LPC implementation with first-order allpass filters. This can have advantages in reducing the bitrate required for a given level of perceived audio quality/intelligibility, especially in wideband audio coding.

History

Warped LPC was first proposed in 1980 by Hans Werner Strube.

References

• Strube, H.W. (1980) Linear prediction on a warped frequency scale, Journal of the Acoustical Society of America, vol. 68, no. 4, pp. 1071-1076, Oct 1980
• Harma, A.; Laine, U.K. (2001) A comparison of warped and conventional linear predictive coding, Speech and Audio Processing, IEEE Transactions on , vol.9, no.5pp.579-588, Jul 2001
• Kruger, E.; Strube, H.W. (1988) Linear prediction on a warped frequency scale, Acoustics, Speech, and Signal Processing [see also IEEE Transactions on Signal Processing], IEEE Transactions on , vol.36, no.9pp.1529-1531, Sep 1988
• Laine, U.K.; Karjalainen, M.; Altosaar, T. (1994) Warped linear prediction (WLP) in speech and audio processing, Acoustics, Speech, and Signal Processing, 1994. ICASSP-94., 1994 IEEE International Conference on , vol.iii, no.pp.III/349-III/352 vol.3, 19-22 Apr 1994