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.

Bit-width optimization of CS-ACELP speech coder by SIMULINK: Core layer of the new G.729.1 standard

Abstract: In this work, we present SIMUIINK bit-true modeling of the conjugate structure-algebraic CELP (CS-ACELP) speech coder which has been chosen as the core layer of speech coder standard ITU-T G.729.1. The optimum bit numbers of the computational blocks are defined as the minimum word-widths that maintain the quality of the output with minimum chip area and power. Such optimum bit-width of the coefficients and the internal computations are extracted. As a result, a golden model of the codec which best suits as a reference for its hardware implementation is developed. The power and area improvements are estimated in two blocks of CS-ACELP speech coder.

Waveform interpolation and analysis-by-synthesis-a good match?

Abstract: This paper considers the incorporation of analysis-by-synthesis (A-by-S) techniques in waveform interpolation (WI) coding architectures. It proposes an altered A-by-S mechanism which overcomes the non-synchronous input/output speech which is characteristic of WI coders. The proposed architectures operate on a prototype-by-prototype basis, optimising parameter choices within each frame. Three possible architectures are considered, with varying degrees of A-by-S integration. These low-rate, 2.4 kb/s coders are tailored to the transmission of no prototype phase information. It is also shown that the incorporation of A-by-S in WI allows exploitation of CELP style perceptual weighting techniques. The conclusion is that the use of A-by-S can improve the perceptual performance of WI coders.

Low-delay subband CELP coding for wideband speech

Abstract: In this paper we propose low-delay techniques for coding 7 kHz speech using subband coding together with code-excited linear predictive coding (CELP). We compare the use of separate as well as joint index codebooks. Specifically, the joint index subband CELP (JISBC) algorithm is found to provide good quality with processing delay in the range of 2.375 ms to 3.375 ms at corresponding bitrates of 16 kbit/s to 8 kbits/s.

Encoder apparatus and method that perform preliminary signal selection for transform coding before main signal selection for transform coding

Abstract: An encoder apparatus is provided that suppresses the quality degradation of encoding processes. An ultimate selection candidate limiting unit uses the spectrum of an input signal and a residual spectrum to designate a given number of pre-selected suppression factors to a CELP component suppressing unit, which uses the designated suppression factors to generate a suppressed spectrum. A CELP residual signal spectrum calculating unit, to which the suppressed spectrum is input, calculates a residual spectrum. A conversion encoding unit uses the residual spectrum to perform a second encoding process. A distortion evaluating unit determines one of the designated suppression factors by use of the spectrum of a second decoded signal generated by decoding a second code obtained by the second encoding process, and further by use of the suppressed spectrum and the spectrum of the input signal.

Voice encoder and voice decoder

Abstract: PROBLEM TO BE SOLVED: To encode a voice signal in high quality by a specified bit rate and a specified encoding delay SOLUTION: An encoding parameter control circuit 31 calculates a frame length from a bit rate and an encoding delay and outputs it to a CELP encoding circuit 32 The encoding parameter control circuit selects a control parameter according to the bit rate from a table on which a plurality of control parameters to control the operation of the CELP encoding circuit on the basis of the calculated frame length are written, and outputs it to the CELP encoding circuit Further, the encoding parameter control circuit outputs a sub frame length and the number of bits allocated to a multi-pulse signal to a multi-pulse generating parameter setting circuit 33 The multi-pulse encoding parameter setting circuit calculates the number of pulses indicating a multi-pulse excitation signal, the number of pulse candidate positions of each pulse, and the candidate positions from the sub frame length and the number of bits of the multi-pulse signal COPYRIGHT: (C)2004,JPO