International Business Machines Corporation

Philippe Elie

Claude R Galand

Michele Rosso

Emmanuel Lancon

Hubert Crepy

Thierry Liethoudt

Some signal coding techniques involve quantizing the signal samples using a signal derived parameter to set the quantizer step. This parameter is then used in the decoding process to synthesize the original signal back to its analog form. Any error affecting the integrity of said parameter, between coding and decoding, would affect the synthesized signal. The method proposed here for protecting data integrity involves, at the encoding site, forcing the parameter to a fixed parity. Then, before synthesizing operations are performed, any parameter failing a parity control test is discarded and replaced with a parameter derived from available valid parameter(s).

Method for eliminating errors in block parameters

A pitch detector to adjust long term prediction in a pulse excitation speech coder. A residual signal r(n) is first derived from the speech signal s(n) by short term filtering. Then, r(n) is processed to calculate a prediction error signal e(n) which is subsequently pulse excitation encoded. The processing of e(n) entails prediction of a residual by measuring a pitch related factor M, employing two steps. First calculating a coarse M value through peak clipping and sign transition detection, and then adjusting the M value by autocorrelation--calculations about the roughly spaced peaks.

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La Gaude, France

Philippe Elie