Topic
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.
Papers published on a yearly basis
Papers
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06 Aug 2008
TL;DR: A new code excited linear predictive (CELP) vocoder based on Adaptive Multi Rate (AMR) 7.4 kbit/s mode that achieves a better compression rate in an environment of Speaker Dependent Coding System (SDSC) and is efficiently used for systems that stores the speech data of a particular speaker.
Abstract: A new code excited linear predictive (CELP) vocoder based on Adaptive Multi Rate (AMR) 7.4 kbit/s mode is proposed in this paper. The proposed vocoder achieves a better compression rate in an environment of Speaker Dependent Coding System (SDSC) and is efficiently used for systems, such as OGM (Outgoing message) and TTS (Text To Speech), that stores the speech data of a particular speaker. In order to enhance the compression rate of a coder, a new Line Spectral Pairs (LSP) codebook is employed by using Centroid Neural Network (CNN) algorithm. Moreover, applying the predicted pulses used in fixed code book searching enhances the quality of synthesis speech. In comparison with original (traditional) AMR 7.4 Kbit/s coder, the new coder shows a superior compression rate and an equivalent quality to AMR coder in term of informal subjective testing Mean Opinion Score(MOS).
6 citations
08 Sep 1998
TL;DR: It is shown that the prediction error is maximally close to an i.i.d. process whose probability density function is given by A exp(-λ|x|p) for minimum-phase Lp-optimal linear predictors.
Abstract: This paper analyzes adaptive linear prediction and the effects of the underlying optiniality criterion on the prediction error. It is well known that the signal-dependent optimization process converts the linear filter into a nonlinear signal processing device and that this will influence the statistics of the filter output in a way not expected from linear filter theory. For minimum-phase L p -optimal linear predictors, we can show that the prediction error is maximally close to an i.i.d. process whose probability density function is given by A exp(-λ|x|p). This result is applied to linear predictive analysis-by-synthesis coding of speech and to predictive decision-feedback equalization of channels with nongaussian noise. Implications for testing time series for linearity or gaussianity are discussed, too.
6 citations
01 Jan 1995
TL;DR: This paper attempts to classify the many different CELP variants that have appeared in the literature since it was first proposed approximately one decade ago, to put everything under a common binding, illustrating common and distinctive features.
Abstract: This paper attempts to classify the many different CELP variants that have appeared in the literature since it was first proposed approximately one decade ago. The main goal is not to compare variants but rather to put everything under a common binding, illustrating common and distinctive features, and also to pinpoint the latest trends that have appeared in this area and which are being used for developing new approaches.
6 citations
NEC1
TL;DR: The subjective test results show that the proposed silence compression algorithm gives no degradation in coding quality for clean and noisy speech signals.
Abstract: This paper proposes a silence compression algorithm operating at multi-rates (MR) and with dual-bandwidths (DB), a narrowband and a wideband, for the MPEG-4 CELP standard The MR/DB operations are implemented by a variable-frame-size/dual-bandwidth voice activity detection (VF/DB-VAD) module with domain conversions of the input signal, and a variable frame-size comfort noise generator (VF-CNG) The CNG module adaptively controls the power smoothing of the decoded signal to improve the coding quality The algorithm also employs a dual-rate discontinuous transmission (DR-DTX) module to reduce an average transmission bit rate during silence periods The subjective test results show that the proposed silence compression algorithm gives no degradation in coding quality for clean and noisy speech signals These signals include about 20 to 30% nonspeech frames and the average transmission bit rates are reduced by 20 to 40% The proposed algorithm has been standardized as a part of the ISO/IEC MPEG-4 CELP version 2
6 citations
Patent•
08 Nov 2002
TL;DR: In this article, a CELP encoder is provided that optimizes excitation vector-related parameters in a more efficient manner than the encoders of the prior art.
Abstract: A CELP encoder is provided that optimizes excitation vector-related parameters in a more efficient manner than the encoders of the prior art. In one embodiment, a CELP encoder optimizes excitation vector-related parameters based on a computed correlation matrix, which matrix is in turn based on a filtered first excitation vector. The encoder then evaluates error minimization criteria based on at least in part on a target signal, which target signal is based on an input signal, and the correlation matrix and generates a excitation vector-related index in response to the error minimization criteria. In another embodiment, a CELP encoder is provided that is capable of jointly optimizing and/or sequentially optimizing multiple excitation vector-related parameters by reference to a joint search weighting factor, thereby invoking an optimal error minimization process.
6 citations