Warped linear predictive coding

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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.


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


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  • Härmä, Aki; Laine, Unto K. (July 2001), "A comparison of warped and conventional linear predictive coding" (PDF), IEEE Transactions on Speech and Audio Processing, 9 (5): 579–588, CiteSeerX, doi:10.1109/89.928922
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  • Laine, Unto K.; Karjalainen, Matti A.; Altosaar, Toomas (April 1994), "Warped linear prediction (WLP) in speech and audio processing" (PDF), 1994 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP-94), vol. III, pp. III–349–III–352, doi:10.1109/ICASSP.1994.390018, ISBN 978-0-7803-1775-8, S2CID 11597755, archived from the original (PDF) on 2016-03-03, retrieved 2014-08-24