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.

Mixed excitation linear prediction coding of wideband speech at 8 kbps

Abstract: This paper presents our study on the feasibility and effectiveness of using the MELP (mixed excitation linear prediction) model for coding wideband (7 kHz) speech signals at a transmission bit rate of 8 kbps. In order to achieve a reasonably good subjective quality for the decoded speech while maintaining a low operating bit rate at the same time, modifications to the pitch estimation, LP analysis/synthesis and post filtering stages of the original MELP model are discussed. Informal listening tests show that the subjective quality of the decoded speech of the proposed coder is rated to be slightly better than the MPEG-4 CELP coder operating at 14.4 kbps for both male and female utterances. The subjective quality of the decoded female utterances from the proposed coder operating at 8.4 kbps is rated to be comparable to that produced by the ITU G.722 coder operating at 48 kbps.

LSP quantization in wideband speech coders

Abstract: This paper deals with multi-stage vector quantization of line spectrum pair (LSP) parameters in wideband speech coders and discusses commonly used spectral distortion measures and their relation to the perceptual quality of the speech coding.

Entropy-constrained linear vector prediction for motion-compensated video coding

Abstract: Theoretical and experimental results for motion-compensated linear prediction of video signals are presented. The rate distortion theory of motion-compensated prediction is extended to linear predictive models. For practical implementations, linear vector predictors are employed. The rate of the motion data is controlled by minimizing a Lagrangian cost function where rate is weighted against distortion using a Lagrange multiplier. An adaptive algorithm for optimally selecting the number of input signals to the linear vector predictor is given.

Residual DPCM for lossless coding in HEVC

Abstract: Incorporating sample-based prediction during lossless coding can significantly improve coding performance. However, its use within a codec designed for lossy coding requires a modification of the available prediction scheme. When implementing the codec, two different prediction processes will have to be implemented. This paper describes a lossless coding scheme that delays the sample-based prediction till the residue coding stage of the codec and carries out prediction in the residual domain. In this way, the prediction scheme of the lossy coder can be retained while realizing the coding gains associated with sample-based prediction. The proposed scheme improves lossless intra coding performance in HEVC Main Profile by an average of 6.5%.

Rate-distortion function for speech coding based on perceptual distortion measure

Abstract: The authors (1992) proposed a perceptual distortion measure for speech coders using an auditory (cochlear) model. This measure evaluates the neural-firing cross-entropy of the coded speech with respect to that of the original speech. Here the output space of the cochlear model is explored using this measure, in order to verify the existence of the pitch and formant information. A rate-distortion analysis for speech coding is provided. A lower bound to the rate-distortion function is evaluated based on the distortion measure, and the exact rate-distortion function is computed using the Blahut (1972) algorithm. Four state-of-the-art speech coders with rates ranging from 4.8 kb/s (CELP) to 32 kb/s (ADPCM) are studied from the viewpoint of their performance with respect to the rate-distortion limits. >