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 practical handbook of speech coders

Abstract: INTRODUCTION SPEECH PRODUCTION The Speech Chain Articulation Source-Filter Model SPEECH ANALYSIS TECHNIQUES Sampling and the Speech Waveform Systems and Filtering z Transform Fourier Transform Discrete Fourier Transform Windowing Signal Segments LINEAR PREDICTION VOCAL TRACT MODELING Sound Propagation in the Vocal Tract Estimation of LP Parameters Transformations of LP Parameters for Quantization Examples of LP Modeling PITCH EXTRACTION Autocorrelation Pitch Extraction Cepstral Pitch Extraction Frequency-Domain Error Minimization Pitch Tracking AUDITORY INFORMATION PROCESSING The Basilar Membrane: A Spectrum Analyzer Critical Bands Thresholds of Audibility and Detectability Monaural Masking QUANTIZATION AND WAVEFORM CODERS Uniform Quantization Nonlinear Quantization Adaptive Quantization Vector Quantization QUALITY EVALUATION Objective Measures Subjective Measures Perceptual Objective Measures VOICE CODING CONCEPTS Channel Vocoder Formant Vocoders The Sinusoidal Speech Coder Linear Prediction Vocoder LINEAR PREDICTION ANALYSIS BY SYNTHESIS Analysis by Synthesis Estimation of Excitation Multi-Pulse Linear Prediction Coder Regular Pulse Excited LP Coder Code Excited Linear Prediction Coder MIXED EXCITATION CODING Multi-Band Excitation Vocoder Mixed Excitation Linear Prediction Coder Split Band LPC Coder Harmonic Vector Excitation Coder Waveform Interpolation Coding PERCEPTUAL SPEECH CODING Auditory Processing of Speech Perceptual Coding Considerations Research in Perceptual Speech Coding APPENDIX: RELATED INTERNET SITES

Reduced complexity signal transmission system

Abstract: In a CELP coder a comparison between a target signal and a plurality of synthetic signals is made. The synthetic signal is derived by filtering a plurality of excitation sequences by a synthesis filter having parameters derived from the target signal. The excitation signal which results in a minimum error between the target signal and the synthetic signal is selected. The search for the best excitation signal requires a substantial computational complexity. To reduce the complexity a preselection of a small number of excitation sequences is made by selecting a small number of excitation sequences resembling the most a backward filtered target signal. With this small number of excitation sequences a full complexity search is made. Due to the reduced number of excitation sequences involved in the final selection the required computational complexity is reduced.

Method for speech coding based on a code excited linear prediction (CELP) model

Abstract: The invention provides a method for speech coding using Code-Excited Linear Prediction (CELP) producing toll-quality speech at data rates between 4 and 16 Kbit/s. The invention uses a series of baseline, implied and adaptive codebooks, comprised of pulse and random codebooks, with associated gain vectors, to characterize the speech. Improved quantization and search techniques to achieve real-time operation, based on the codebooks and gains, are also provided.

Phonetically-based vector excitation coding of speech at 3.6 kbps

Abstract: A phonetically based segmentation of speech is performed to classify segments into five classes: onset, unvoiced low-pass voiced, steady-state voiced, and transient voiced. The segment lengths are constrained to an integer multiple of a unit-frame. For each segment class, a distinctive coding scheme based on vector excitation coding (VXC) is used. The maximum bit-rate is 3.6 kb/s, and a moderate coding delay of 45 ms is incurred. Performance is roughly comparable to conventional VXC/CELP (code-excited linear prediction) coding at 4.8 kb/s. >

Dynamic codebook for efficient speech coding based on algebraic codes

Abstract: A method of encoding a speech signal is presented. This method improves the excitation codebook and search procedure of the conventional Code Excited Linear Prediction (CELP) speech encoders. Use is made of a dynamic codebook (201, 202) based on the combination of two modules: a sparse algebraic code generator (201) associated to a filter (202) having a transfer function varying in time. The generator (102) is a structured codebook with codewords having very few non zero components. The filter (202) shapes the spectral characteristics whereby the resulting excitation codebook (201, 202) exhibits favorable perceptual properties. The search complexity in finding the best codeword is greatly reduced by bringing the search back to the algebraic code domain thereby allowing the sparsity of the algebraic code to speed up the necessary computations.