Sip - Societa Italiana Per L-esercizio Delle Telecomunicazioni P.a.

Robert Boschgmbh

Cselt-centro Studi E Laboratori Telecomunicazioni S.p.a.

Luca Cellario

Daniele Sereno

Michele Festa

Jorg Muller

Object oriented audio coding

A method and a device for speech signal digital coding are provided where at each frame there is carried out a long-term analysis for estimating pitch period d and a long- term prediction coefficient b and gain G, and an a-priori classification of the signal as active/inactive and, for active signal, as voiced/unvoiced. Period estimation circuits (LT1) compute such period on the basis of a suitably weighted covariance function, and classification circuits (RV) distinguish voiced signals from unvoiced signals by comparing long-term prediction coefficient and gain with frame-by-frame variable thresholds.

Method and device for speech signal pitch period estimation and

An optimum excitation signal for each subframe is determined in a speech coder based on analysis-by-synthesis techniques and operating on frames of samples divided into a number of subframes. The excitation signal includes a shape contribution (innovation) and an amplitude contribution (gain) which are quantized separately. A circuit (IT) for gain quantization includes means (QU) for determining a gain index for each subframe; a comparison logic network (CFR) for detecting the maximum value taken by the gain index in the frame; and means for computing a normalized index for each subframe as a difference between the maximum index and the gain index relevant to that subframe. The coded signal includes the coded values of the maximum index and of the normalized indexes as information on the gain relevant to a frame.

Method of and device for quantizing excitation gains in speech coders

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Turin, Italy

Luca Cellario