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.

Description of a hybrid 7.2 kbps vocoder

Abstract: A speech bandwidth compression system is described which employs a hybrid processing approach combining a baseband system and a Linear Predictive Coding system to produce high quality speech at a transmission rate of 7.2 Kbps. The system requires the extraction and transmission of excitation parameters, but is not very sensitive to errors in those parameters nor is it particularly sensitive to errors in the baseband portion of the processing. Since the system is composed of two independent processes, errors in one process have no effect on the other process and the system is remarkably robust. The system is essentially a modification of a similar system which was operated at 16 Kbps (1) which utilizes unique coding techniques to reduce the bit rate to 7.2 Kbps.

Method and apparatus for layered code-excited linear prediction speech utilizing linear prediction excitation corresponding to optimal gains

Abstract: A layered code-excited linear prediction (CELP) encoder, an Adaptive Multirate Wideband (AMR-WB) encoder and methods of CELP encoding and decoding. In one embodiment, the encoder includes: (1) a core layer subencoder and (2) at least one enhancement layer subencoder, at least one of the core layer subencoder and the enhancement layer subencoder having first and second adaptive codebooks and configured to retrieve a pitch lag estimate from the second adaptive codebook and perform a closed-loop search of the first adaptive codebook based on the pitch lag estimate.

A mixed harmonic excitation linear predictive speech coding for low bit rate applications

Abstract: The mixed harmonic excitation linear predictive speech coder (MHE-LPC) is based on a technique derived from the multi-band excitation (MBE) and multi-band linear predictive coding (MB-LPC) types of speech coding algorithms The MHE-LPC coder has the potential of producing high quality speech at 48 kb/s and below This coder employs a new pitch estimation and a mixed voicing technique that utilizes a number of bands within the 4 kHz speech bandwidth (6-8 bands), each band having a voicing probability that defines voiced and unvoiced portions of the excitation spectrum In addition to these, a new DCT based LPC and residual amplitude quantization technique has been developed and is described in this paper The 36 kb/s MHE-LPC coder with 14th order LPC filter was found to produce better speech quality than various other low rate speech coding standards During an informal listening test, the 36 kb/s MHE-LPC vocoder produced better performance than the 36 kb/s INMARSAT Mini-M coder The MHE-LPC algorithm can be easily extended to bit rates between 12 and 8 kb/s depending on the applications

Low bit-rate image coding using 2-D linear prediction and 2-D stochastic excitation

Abstract: The use of stochastic excited linear predictive coding method is investigated for image coding and its parameters are studied. It is shown that it is not necessary to transmit local bias values of the image frames. It is also shown that the stochastic excitation is not adequate to represent the prediction residual signal. In order to get good performance from this coder, it is necessary to generate the codebook from the actual prediction residual signal. >