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.
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Patent•
NEC1
TL;DR: In this article, a CELP (code excitation linearly predictive) coding circuit was proposed to make the voice coding and decoding device based on a hierarchical coding highly efficient.
Abstract: PROBLEM TO BE SOLVED: To make the voice coding and decoding device based on a hierarchical coding highly efficient. SOLUTION: A first CELP(code excitation linearly predictive) coding circuit 14 which receives a signal in which an input signal is down-sampled in a down- sampling circuit 1 outputs one part of its coded output to a second CELP coding circuit 15, which codes the input signal based on the coded output of the first CELP coding circuit 14 and a multiplexer 7 outputs coded outputs of the first and second CELP coding circuits in a bit stream and a demultiplexer 18 outputs the coded output of the circuit 14 from the bit stream to a first CELP decoding circuit 16 when a control signal is a low bit rate and extracts the one part of the output of the circuit 14 and the output of the circuit 15 when the control signal is a high bit rate to output them to a second CELP decoding circuit 17 and outputs outputs of the circuits 16, 17 via a switch circuit 19.
11 citations
01 Jan 1984
TL;DR: If one approximates the vocal tract as a series of fixed length tubes (which is equivalent to representing it as an all-pole digital filter) it becomes possible to predict successive samples of the speech wave as linear combinations of previous samples.
Abstract: If one approximates the vocal tract as a series of fixed length tubes (which is equivalent to representing it as an all-pole digital filter) it becomes possible to predict successive samples of the speech wave as linear combinations of previous samples. The coefficients in the linear combination characterize the shape of the vocal tract. A sequence of sets of coefficients can be used to characterize the changing shape of the vocal tract over time. This representation is widely used because of the particularly efficient algorithms associated with it.
11 citations
Journal Article•
01 Nov 2008-The Transactions of the Institute of Electronics,Information and Communication Engineers. A
TL;DR: Familiarity, ease of access, trust, and awareness of benefits and risks are important.
Abstract: 線形予測分析に基づく時系列信号の可逆圧縮符号化 方式は,時系列信号を線形予測分析し,その結果求ま る線形予測係数あるいは PARCOR 係数と予測誤差 (残差)を符号化して伝送し,受信側で無歪に復号化 できる仕組みとなっている.線形予測分析により生成 される残差信号の振幅は通常 0付近に集中するという 性質を利用し,出現頻度の高い値ほど短い符号を割り 当てる Golomb-Rice符号 [1]をはじめとするエントロ ピー符号化を残差の符号化に用いることで全体の符号 量を小さく抑えようとする点がこの方式の特徴である. Golomb-Rice符号の場合,残差振幅に割り当てられる 符号量は,振幅の絶対値とほぼ比例関係にあるため, 残差符号量は残差振幅の絶対値和である程度よく近似 される.したがって,残差振幅の絶対値和が小さいほ ど符号量はより小さくできる可能性がある.しかしな がら,従来の線形予測分析による可逆圧縮符号化方式 では,残差振幅の二乗和を最小化するように予測係数 を求めるため,残差符号量を直接的に最小化する規準
11 citations
05 Jun 2000
TL;DR: This paper presents a dispersed-pulse codebook for CELP coder that generates an excitation vector by convoluting dispersion vectors with signed pulses in an algebraic codevector and shows that the coding distortion with this codebook is smaller than that with angebraic codebook.
Abstract: This paper presents a dispersed-pulse codebook for CELP coder. This codebook generates an excitation vector by convoluting dispersion vectors with signed pulses in an algebraic codevector. The dispersion vectors are obtained through training so the coding distortion to be reduced. An objective evaluation result shows that the coding distortion with this codebook is smaller than that with an algebraic codebook. The dispersed-pulse codebook is applied to a 4 kb/s CELP coder. Subjective evaluation results show that: (1) the fundamental performance of the 4 kb/s coder is equivalent to that of G.726 32 kb/s coder, and (2) the performances of the 4k b/s coder under some error and background noise conditions are equivalent to those of G.729 8 kb/s coder.
10 citations
TL;DR: A new speech coding model targeted at the bit-rate above 4 kbit/s, referred to as multiband code-excited linear prediction (MBCELP), which reconstructed very high quality speech without ‘buzziness’ or ‘hoarseness’ for both clean and noisy speech.
10 citations