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 New Architecture Model for Multi Pulse Linear Predictive Coder for Low-Bit-Rate Speech Coding

Abstract: Speech coding is a very important area that finds civilian and military applications. It deals with the problem of reducing the bit rate required for the speech representation while preserving the quality of the speech which reconstructed from that representation. In this paper, we focused on developing algorithms and methods for a waveform speech coder operating at low bit rate with high quality reconstructed speech signal. Therefore, a new model for linear predictive coding of speech that can be used to produce high quality speech at low data rate is introduced. In this model, the residual (excitation signal) encoding is based on selecting the important pulses in the residual signal rather than encoding all pulses. Hence, this vocoder forms an excitation sequence which consists of multiple non-uniformly spaced pulses. During analysis, both the amplitude and location of the pulses are determined. In addition, this paper involves new techniques in the process of modeling and encoding of the amplitude and location of each pulse as well as linear prediction parameters.

Structured Stochastic Codebook and Codebook Adaptation for CELP

Abstract: Since its introduction in 1984, Code Excited Linear Prediction (CELP) [1] has been intensively investigated as a promising coding algorithm for providing good quality speech at low bit rates. CELP is the name for a class of coding algorithms that employs vector quantization (VQ) using a perceptually weighted error criterion measured in an Analysis-by-Synthesis loop. This process gives an efficient representation of the excitation signal and exhibits better performance than conventional coding methods. However, the codebook search requires a huge computational load, which is a major drawback in the practical implementation of CELP. In particular, for digital cellular communications, which is considered the biggest application for low bit-rate speech coding, reducing the complexity of CELP is important for small hardware size and low power consumption.

Speech decoding and encoding apparatus for lost frame concealment using predetermined number of waveform samples peripheral to the lost frame

Abstract: An audio decoding device capable of suppressing an information amount for a lost flame compensation process and encoding efficiency is provided. A decoded sound source generator generates a lost frame's CELP decoded sound source signal. A pitch pulse information decoder CELP decodes a pitch pulse position information and a pitch pulse amplitude information. A pitch pulse waveform learner learns a pitch pulse learning waveform in a past frame in advance from the lost frame. A convolution adjuster amplitude-adjusts the pitch pulse learning waveform according to the pitch pulse amplitude information by considering a predetermined number of waveforms peripheral to a peak position of the lost frame's CELP decoded excitation signal, and convolutes a pitch pulse waveform into a time axis which has been amplitude-adjusted according to the pitch pulse position information. A sound source signal corrector adds or replaces the pitch pulse waveform convoluted into the time axis to the lost flame decoded sound source signal.