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.

Vocoder with efficient, fault tolerant excitation vector encoding

Abstract: A CELP vocoder efficiently encodes an excitation vector in a way that is less sensitive to single bit errors. Each of the pulses composing the excitation vector are limited to one of four predetermined positions. As a result, only three bits are required to encode each pulse (two bits for position and one sign bit) and, in addition, a single bit error only produces an error in one pulse.

CELP-coded speech parameter decoding method and apparatus

Abstract: Provided is a parameter decoding device for a CELP-type encoded speech signal which performs parameter compensation process so as to suppress degradation of a main observation quality in a prediction quantization The parameter decoding device includes amplifiers (305-1 to 305-M) which multiply inputted quantization prediction residual vectors x n-1 to x n-M by a weighting coefficient β 1 to β M The amplifier (306) multiplies the preceding frame decoding LSF vector y n-1 by the weighting coefficient β -1 The amplifier (307) multiplies the code vector x n+1 outputted from a codebook (301) by the weighting coefficient β 0 An adder (308) calculates the total of the vectors outputted from the amplifiers (305-1 to 305-M), the amplifier (306), and the amplifier (307) A selector switch (309) selects the vector outputted from the adder (308) if the frame erasure coding B n of the current frame indicates that 'the n-th frame is an erased frame' and the frame erasure coding B n+1 of the next frame indicates that 'the n+1-th frame is a normal frame'

Code excited linear prediction codec for electrocardiogram

Abstract: In This work we propose a CELP ECG codec for medical telemetry. The encoding algorithm is based on code-excited linear prediction (CELP). The general framework proposed is: QRS detection, calculation of LPC parameter, generation of residual error signal, codebook generation, MSE (mean square error) search. The codebook is generated for residual error. The indices of the codebook and corresponding LPC parameters are transmitted where the minimum MSE occurs. A replica of the transmitter codebook is present at the receiver. Corresponding to the received index value residual error coefficients are retrieved from the receiver codebook. The ECG signal is reconstructed from the retrieved code word.

Adaptive window excitation coding in low-bit-rate CELP coders

Abstract: A new paradigm for efficient coding of the fixed-codebook excitation in CELP coders at low-bit rates is presented. In this scheme, the non-zero components of the fixed-codebook excitation are localized to a set of windows whose locations are dependent on the pitch frequency and on the energy contour of a modified residual signal. Highly efficient coding is thus achieved by allocating most of the fixed excitation bits to capture the essential excitation events. The paradigm is validated by computer simulation of a variable-rate speech codec. The performance of the codec is evaluated by informal subjective tests comparing it with TIA standard variable rate speech codecs. The results confirm that the proposed scheme can be used to reproduce speech at average bit rates from 2.3 to 3.4 kbps with very high quality and intelligibility.

Performance of the CELP speech codec in channel with common fading

Abstract: We present results of simulation of a low-bit rate speech transmission system in a channel with common Rayleigh fading. The system uses code-excited linear voice prediction (CELP) and the channel errors correction. The quality of the speech restoration provided by the system is estimated with the help of two tests. The first one is the well known intelligibility diagnostic rhyme test (DRT) and the second one is the mean opinion score (MOS). The system considered appears to be rather robust i.e., demonstrates high noise and fading immunity and provides good speech quality for the bit-rate 4.8 kb/s in channels with the bit-error rate not exceeding 10/sup -2/.