Code-excited linear prediction

About: Code-excited linear prediction is a research topic. Over the lifetime, 2025 publications have been published within this topic receiving 28633 citations. The topic is also known as: CELP.

CELP-based speaker verification: an evaluation under noisy conditions

Abstract: We propose a text-independent speaker verification method based on a speech coding scheme. The proposed method utilizes CELP parameters which are used in speech coding schemes for mobile communication systems, and verifies a speaker only with the encoded speech information. The reliability of the proposed method under noisy conditions is mainly discussed with some simulation results.

Transform-domain codebook in a celp coder and decoder

Abstract: Codebook Arrangement for use in coding an input sound signal includes First and Second Codebook Stages. First Codebook Stage includes one of a time-domain CELP codebook and a transform-domain codebook. Second Codebook Stage follows the first codebook stage and includes the other of the time-domain CELP codebook and the transform-domain codebook. Codebook Stage includes an adaptive codebook may be provided before First Codebook Stage. A selector may be provided to select an order of the time-domain CELP codebook and the transform-domain codebook in First and Second Codebook Stages, respectively, as a function of characteristics of the input sound signal. The selector may also be responsive to both the characteristics of the input sound signal and a bit rate of the codec using Codebook Arrangement to bypass Second Codebook Stage. Codebook Arrangement can be used in a coder of an input sound signal.

Voice encoding method

Abstract: PURPOSE:To provide the encoding system which reduces the degradation of voice quality and does not make a tone change conspicuous even at a low bit rate by providing a pulse information code book, pulse generating means and pulse sound source retrieving means. CONSTITUTION:This method is based on a code drive linear prediction(CELP) voice encoding system. In this case, long-term predictive analysis is executed at every sub frame by retrieving an adaptive code book. A signal subtracting a weighted long-term prediction vector further multiplied by a gain from a signal 24 subtracting a zero input response from a weighted input signal 20 is inputted to a pulse sound source retrieving means 32. In the case of retrieving the pulse sound source, pulse intervals and head information are read from a pulse information code book 33, and a pulse sequence is generated by a pulse generator 35. This pulse train is defined as a sound source vector and weighted by means of convolution of the impulse response of a weighted synthesizing filter 21, and the gain and a pulse sound source vector for minimizing error are decided.

A robust, low complexity 5.0 kbps stochastic coder for a noisy satellite channel

Abstract: A code excited linear predictive coding (CELP) based coder operating at 5065 bps is presented. The coder uses a self-excitation sequence for long-term prediction in addition to a fixed codebook populated with stochastic multipulse vectors as the excitation signal. The authors describe how the complexity of the coder is reduced, and present methods of increasing its spectral robustness, thus making it a suitable candidate for mobile satellite communication. The complexity is greatly reduced by using overlapping codevectors in both the adaptive and multipulse codebook. For robustness a filter correction scheme is derived, which, together with frame repetition techniques, will let the coder operate with little perceivable degradation in burst durations up to 40 ms. >

Circular linear prediction modeling for speech coding applications

Abstract: Previously, we introduced a window-less linear-prediction method known as circular linear prediction (CLP) modeling for pitch-synchronous analysis of the speech spectrum. This paper presents the spectral estimation properties of the CLP method using various synthetic speech signals including fully-voiced, unvoiced and partially-voiced speech signals. As the true spectrum is known, it is possible to make objective measurements on how well the CLP method estimates the true spectrum. In addition, a multi-cycle generalization of the CLP method is proposed. This new method improves the spectral estimation performance of the CLP method for short pitch cycles (less than 7.5 ms). These experiments prove that the CLP method and its multi-cycle generalization are viable alternatives to the autocorrelation method for modeling speech signal, especially in transition regions.