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.

A distance measure based on the derivative of linear prediction phase spectrum

Abstract: A new distance measure based on the derivative of linear prediction (LP) phase spectrum is proposed for comparison of speech spectra. Relationships among several distance measures based on the linear prediction coefficients (LPCs) are discussed. The advantages of the new measure and an efficient method of computing it are also discussed.

Pitch-synchronous speech coding by applying multiple analysis to select and align a plurality of types of code vectors

Abstract: A speech coder using a pitch synchronous innovation code excited linear prediction (PSI-CELP) speech coding system. The speech coder is capable of representing a portion which is not sufficiently represented by an adaptive codebook in a periodic portion of input speech and capable of improving the quality of reproduced speech. The periodicity corresponds to the pitch cycle of input speech by preliminarily reproducing speech from simple impulse trains. The speech coder depending on the particular embodiment includes an adaptive code book, a fixed code book, a noise code book, and a pulse codebook. A pulse code book stores a plurality of types of codevectors corresponding to pitch waveforms of voiced sounds. At the time of coding input speech, the pulse code book is searched.

Speech Coding: A Computer Laboratory Textbook

Abstract: DSPLAB: The DSP Laboratory Software. Quantization: PCM and APCM. Waveform Coding with Fixed Prediction. Pitch-excited Linear Predictive Vocoder. Waveform Coding with Adaptive Prediction. Analysis-by-Synthesis LPC. Subband Coding. Projects. Appendices. Bibliography. Index.

Code excited linear predictive vocoder and method of operation

Abstract: Apparatus (101-112) for encoding speech using an improved code excited linear predictive (CELP) encoder (106, 104) using a virtual searching technique (708-712) to improve performance during speech transitions such as from unvoiced to voiced regions of speech. The encoder compares candidate excitation vectors stored in a codebook with a target excitation vector representing a frame of speech to determine the candidate vector that best matches the target vector by repeating a first portion of each candidate vector into a second portion of each candidate vector. For increased performance, a stochastically excited linear predictive (SELP) encoder (105, 107) is used in series with the adaptive CELP encoder. The SELP encoder is responsive to the difference between the target vector and the best matched candidate vector to search its own overlapping codebook in a recursive manner to determine a candidate vector that provides the best match. Both of the best matched candidate vectors are used in speech synthesis.

Techniques for improving the performance of CELP type speech coders

Abstract: Techniques for improving the performance of CELP (code excited linear prediction) type speech coders while maintaining reasonable computational complexity are explored. A harmonic noise weighting function which enhances the perceptual quality of the processed speech is introduced. The combination of harmonic noise weighting and subsample resolution pitch significantly improves the coder performance for voiced speech. A 6.9 kb/s VSELP speech coder which incorporates subsample resolution pitch and harmonic noise weighting is described. Complexity reduction techniques are discussed which allow the coder to be implemented using a single fixed point digital signal processor. >