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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
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Proceedings ArticleDOI
13 Apr 1994
TL;DR: It has been reported that in a CELP vocoder the perceptual quality of synthesized speech can be improved by replacing the traditional stochastic codebook with a mixed codebook containing periodic SP (single-pulse) and noise-like sequences.
Abstract: It has been reported that in a CELP vocoder the perceptual quality of synthesized speech can be improved by replacing the traditional stochastic codebook with a mixed codebook containing periodic SP (single-pulse) and noise-like sequences. At the bit rate of 4 kb/s, the frame and subframe sizes are relatively long to reduce the bit rates for coding the gains and the synthesis filter parameters. In this case, the coding of noise-like sequences requires many more bits than the coding of periodic SP sequences to obtain high-quality speech, thus, a periodic DP (double-pulse) excitation can be introduced while the bit rate required to code the excitation is not significantly increased. In the 4 kb/s DP-CELP vocoder presented in the paper, a mixed codebook containing periodic SP and binary noise-like sequences is first searched, avoiding V/UV decision and exhaustive searching of all possible candidates. If the optimal sequence is of periodic SP, a second periodic SP sequence is combined with it to generate a periodic DP excitation. In the decoder, a proposed short-term postfilter is added to increase the clarity of synthesized speech. >

8 citations

Proceedings ArticleDOI
14 May 2006
TL;DR: Evaluating different configurations in a subjective listening test shows that the proposed method offers significant improvements in sinusoidal coding, and the properties of the frequency-domain linear prediction-based envelope estimator are analyzed.
Abstract: A method for amplitude modulated sinusoidal audio coding is presented that has low complexity and low delay. This is based on a sub-band processing system, where, in each subband, the signal is modeled as an amplitude modulated sum of sinusoids. The envelopes are estimated using frequency-domain linear prediction and the prediction coefficients are quantized. As a proof of concept, we evaluate different configurations in a subjective listening test, and this shows that the proposed method offers significant improvements in sinusoidal coding. Furthermore, the properties of the frequency-domain linear prediction-based envelope estimator are analyzed

8 citations

Proceedings ArticleDOI
07 Sep 1997
TL;DR: This paper proposes a 16 kbit/s wideband CELP coder with a high-order backward predictor and its fast coefficient calculation method, which approximately calculates the autocorrelations of the residual signal from those of the decoded output signal.
Abstract: This paper proposes a 16 kbit/s wideband CELP coder with a high-order backward predictor and its fast coefficient calculation method. The coefficients are calculated from autocorrelations of the residual signal. The proposed calculation scheme approximately calculates the autocorrelations of the residual signal from those of the decoded output signal. Therefore, an inverse filtering of the decoded output signal and a calculation for the autocorrelations of the residual signal are not necessary, and the complexity for the backward prediction is drastically reduced. The proposed coder also adopts a multi-pulse vector quantization to efficiently represent an excitation signal as well as a multi-mode coding to enhance the performance and the channel error robustness. An MOS test shows that the proposed coder achieves superior performance for speech to that of ITU-T G.722 at 56 kbit/s and comparable performance for audio to that of G.722 at 48 kbit/s.

8 citations

Patent
19 Sep 1996
TL;DR: An improved pitch searching time reducing method for a CELP vocoder using a Line Spectral Pair (LSP) frequency which is capable of significantly reducing the pitch search time by separating the speech signal using a first formant frequency of the line spectral pair of the digital type personal communication system is presented in this paper.
Abstract: An improved pitch searching time reducing method for a CELP vocoder using a Line Spectral Pair (LSP) frequency which is capable of significantly reducing the pitch search time by separating the speech signal using a first formant frequency of the line spectral pair of the digital type personal communication system, which includes the steps of computing a decimation interval of a pitch search interval using an LSP frequency of a first formant computed by a formant filter so as to compute a preparatory pitch of a given speech; determining a preparatory pitch to be used when searching a pitch by detecting a peak and a valley within each decimation interval; and computing a preparatory pitch by adapting a first formant frequency of an LSP computed by a formant filter with a decimation rate and performing a pitch search with respect to the obtained preparatory pitch.

8 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20226
20213
20207
201915
201810
201713