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
all-pass 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.
Kruger, Elmar; Strube, Hans Werner (September 1988), "Linear prediction on a warped frequency scale", IEEE Transactions on Acoustics, Speech, and Signal Processing, 36 (9): 1529–1531,
doi:
10.1109/29.90384