Basically all conventional digital signal processing techniques can be warped by introducing a simple modification to the system. In this paper, the focus is in warped linear predictive coding techniques with applicat...
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Basically all conventional digital signal processing techniques can be warped by introducing a simple modification to the system. In this paper, the focus is in warped linear predictive coding techniques with application to speech and audio coding. The performance of warped LPC is compared with a conventional LPC in listening tests and in terms of technical measures. This is done at various sampling rates as a function of the order of the LPC model.
The reliable communication of FS CELP 10 16 encoded speech over very noisy channels is investigated. Using second-order Markov chains it is shown that over one-quarter of the CELP bits in every frame of speech are red...
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The reliable communication of FS CELP 10 16 encoded speech over very noisy channels is investigated. Using second-order Markov chains it is shown that over one-quarter of the CELP bits in every frame of speech are redundant. An unequal error protection coding scheme, which exploits this residual redundancy, is proposed for sending the CELP parameters over Gaussian and Rayleigh fading channels. Simulations indicate substantial coding gains over conventional systems.
In this paper, a 6.7-kbps vector sum excited linear prediction (VSELP) coder with less computational complexity is presented. A very efficient VSELP codebook with nine basis vectors and a heuristic K-selection method ...
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In this paper, a 6.7-kbps vector sum excited linear prediction (VSELP) coder with less computational complexity is presented. A very efficient VSELP codebook with nine basis vectors and a heuristic K-selection method (to reduce the search space and complexity) is constructed to obtain the stochastic codebook vector. The nine basis vectors are obtained by optimizing a set of randomly generated basis vectors. During the optimization process, we have trained the basis vectors to give the system apriori knowledge of the characteristics of the input. The coder is implemented on a TMS320C541 digital signal processor. The performance is evaluated by testing the 6.7-kbps VSELP coder with different test speech data taken from different speakers. The quality of the coder is estimated by comparing the performance of the 6.7-kbps VSELP coder with an 8-kbps VSELP speech coder based on the IS-54 standards. (C) 2002 Elsevier Science B.V. All rights reserved.
An efficient method to implement the perceptual posterfilter for the suppression of coding noise in CELP-coded speech is proposed. The method is based on approximating the response of an all-pole filter to the respons...
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An efficient method to implement the perceptual posterfilter for the suppression of coding noise in CELP-coded speech is proposed. The method is based on approximating the response of an all-pole filter to the response of the pole-zero form postfilter via cepstrum processing. This all-pole postfilter can then be implemented more efficiently than the pole-zero postfilter with less computation and filter memory.
An iterative algorithm for codebook accuracy enhancement, applicable to both waveform and linear prediction (LP) model-based vector quantisation in nonorthogonal domains, is developed and presented. Sample results are...
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An iterative algorithm for codebook accuracy enhancement, applicable to both waveform and linear prediction (LP) model-based vector quantisation in nonorthogonal domains, is developed and presented. Sample results are provided which clearly demonstrate the improved performance for the same bit rate.
A novel frame interpolation technique for two-band linear predictive coding (LPC) vocoders is proposed for maintaining natural speech quality at bit rates below I kbit/s. Experimental results show that the speech qual...
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A novel frame interpolation technique for two-band linear predictive coding (LPC) vocoders is proposed for maintaining natural speech quality at bit rates below I kbit/s. Experimental results show that the speech quality of the proposed vocoder is quite natural at bit rates 880 bit/s and comparable to that of 4.8 kbit/s CELP.
We present a predictive neural network called neural predictivecoding (NPC). This model is used for nonlinear discriminant features extraction applied to phoneme recognition. We validate the nonlinear prediction impr...
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We present a predictive neural network called neural predictivecoding (NPC). This model is used for nonlinear discriminant features extraction applied to phoneme recognition. We validate the nonlinear prediction improvement of the NPC model. We also, present a new extension of the NPC model: NPC-3. In order to evaluate the performances of the NPC-3 model, we carried out a study of Darpa-Timit phonemes (in particular /b/, /d/, /g/ and /p/, /t/, /q/ phonemes) recognition. Comparisons with traditional coding methods are presented. We also show how an adaptative constraint allows improvements on the recognition task.
We present a new architecture called the Modular Neural predictivecoding architecture (Modular NPC). This architecture is used for speech discriminant feature extraction (DFE). We present an application of the modula...
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ISBN:
(纸本)9810475241
We present a new architecture called the Modular Neural predictivecoding architecture (Modular NPC). This architecture is used for speech discriminant feature extraction (DFE). We present an application of the modular NPC architecture on phoneme recognition task. The phonemes which are extracted from the Darpa-Timit speech database are: vowels, /b/-/d/-/g/ and /p/-/t/-/k/ phonemes. Comparisons with coding methods (LPC, MFCC, PLP) are presented.
Low-complexity scalable methods are of importance to achieve multi-rate and variable rate speech coding. Adopting the CELP concept, we focus on the innovation coding, suggesting an adaptive companding VQ. We present a...
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ISBN:
(纸本)0780374029
Low-complexity scalable methods are of importance to achieve multi-rate and variable rate speech coding. Adopting the CELP concept, we focus on the innovation coding, suggesting an adaptive companding VQ. We present a scheme having essentially no increase in complexity as the rate is increased, yet having a competitive distortion performance. This is acheived by avoiding an explicit perceptual filtering step in the coding, still utilizing close to optimal VQ techniques in a perceptual domain. Subjective and objective distortion performance is better than, or in parity with, that of conventional white noise excitation methods or multipulse structures.
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