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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TL;DR: The proposed algorithm aims at the determination of a binary pulses excitation sequence according to a pulse positioning approach rather than to a codebook search as in CELP.
Abstract: Multipulse modelling is a widely used technique for medium-rate speech coding. Lower bit-rates can be achieved using binary excitation sequences, as in CELP speech coders. This paper describes an application of simulated annealing heuristics to low bit-rate speech coding. The proposed algorithm aims at the determination of a binary pulses excitation sequence according to a pulse positioning approach rather than to a codebook search as in CELP. Performance and complexity issues are discussed and show that the algorithm is a viable alternative to CELP.
18 Mar 1994
TL;DR: The results indicated that when the noise cancellation preprocessor was added to the CELP encoder, the DRT intelligibility scores were improved by a significant 5.0 points, making the speech much more acceptable for possible use in the F/A-18.
Abstract: : Because of the severe noise environment in the Navy's F/A-18 jet aircraft, it has always been very difficult to achieve highly intelligible speech using low data rate voice encoders such as the 2.4 kbps LPC-10. As a result, all voice encoding has been done with a high data rate 16.0 kbps CVSD algorithm. The main focus of this research was to develop a technique that could retain the acceptable intelligibility of the high rate encoders while still significantly lowering the data rate required. To achieve these results, a noise cancellation preprocessor was developed to be used in tandem with the new 4.8 . kbps CELP encoder that is being implemented in the STU-III. While many noise reduction techniques were investigated, the best results were accomplished by first reducing the noise through spectral subtraction and then enhancing the important resonant formants of the speech. The results indicated that when the noise cancellation preprocessor was added to the CELP encoder, the DRT intelligibility scores were improved by a significant 5.0 points, making the speech much more acceptable for possible use in the F/A-18. Noise cancellation, Spectral subtraction. Digital filtering.
Patent•
20 Jan 2016TL;DR: In this article, a CELP-type speech coding apparatus includes a parameter quantizer that selects an adaptive codebook vector and a fixed codebookvector so as to minimize an error between a synthesized speech signal and an input speech signal.
Abstract: In a CELP-type speech coding apparatus, switching between an orthogonal search of a fixed codebook and a non-orthogonal search is performed in a practical and effective manner. The CELP-type speech coding apparatus includes a parameter quantizer that selects an adaptive codebook vector and a fixed codebook vector so as to minimize an error between a synthesized speech signal and an input speech signal. The parameter quantizer includes a fixed codebook searcher that switches between the orthogonal fixed codebook search and the non-orthogonal fixed codebook search based on a correlation value between a target vector for the fixed codebook search and the adaptive codebook vector obtained as a result of a synthesis filtering process.
07 May 1996
TL;DR: A hybrid input/output block adaptation scheme for the quantization of spectral parameters for low-delay CELP coders to compensate for the spectrum distortion introduced by conventional backward adaptation schemes operating at low bit rates.
Abstract: This paper describes a hybrid input/output block adaptation scheme for the quantization of spectral parameters for low-delay CELP coders. In this scheme, line spectrum pair (LSP) coefficients are used as parameters for spectral adaptation and they are partitioned into two segments; LSPs in the first segment which corresponding to low frequency regions are backward adapted from the reproduction speech while LSPs in the second segment are adapted from input speech and quantized as side information to the decoder. The rationale behind this scheme is to compensate for the spectrum distortion introduced by conventional backward adaptation schemes operating at low bit rates. Simulation results show that the hybrid LSP adaptation scheme achieves transparent quantization at 12 bits for each analysis frame of 5 ms.
Patent•
05 Apr 2006
TL;DR: In this paper, a method and an arrangement to provide a common platform for the encoder and decoder of various CELP codecs used during data/speech transmission within a communication network, wherein common portions (1 to 4) of said codecs were extracted and implemented on the common platform communicating with the remaining portions (5 to 10).
Abstract: A method and an arrangement to provide a common platform for the encoder and decoder of various CELP codecs used during data/speech transmission within a communication network, wherein common portions (1 to 4) of said codecs were extracted and implemented on the common platform communicating with the remaining portions (5 to 10) of said codecs.