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.

Adaptive speech coder having code excited linear prediction with multiple codebook searches

Abstract: Methods and apparatus for determining codevectors in response to a speech signal including an adaptive-stochastic codebook search combination. Each stochastic codebook search is made up of BPC and SHC search components (124). The speech signal is used as the input to each of the two possible codebook searches, LTP-CB1 and CB0-CB1. The codebook target vector is computed at (120). The present invention determines when it is desirable to dispense with the adaptive LTP analysis (122) of the target vector and instead use the bits freed up by foregoing the LTP to add another codevector obtained from a second stochastic codebook to the modeling process. A first synthesized speech signal can be determined from the first and second codevectors and a second synthesized speech can be determined from the first and second codewords. The error between the synthesized and the input speech signals is computed (126), concurrently the SHC/BPC search for codebook is performed (128). The resultant vector is searched in the SHC/BPC (124) search for codebook 1 (130).

Estimation of speech energy based on code excited linear prediction (CELP) parameters extracted from a partially- decoded CELP-encoded bit stream and applications of same

Abstract: Methods, systems, and non-transitory computer readable media for estimating speech energy of an encoded bit stream based on coding parameters extracted from the partially-decoded bit stream are disclosed. According to one aspect, a method for estimating speech energy of an encoded bit stream based on coding parameters extracted from the partially-decoded bit stream includes receiving a CELP-encoded bit stream, partially decoding the bit stream, and estimating the speech energy of the bit stream based a set of four or fewer CELP parameters extracted from the partially decoded bit stream. According to another aspect, a method for estimating speech energy of an encoded bit stream based on coding parameters extracted from the partially-decoded bit stream includes receiving a CELP-encoded bit stream, partially decoding the bit stream, extracting at least one CELP parameter from the partially-decoded bit stream, and estimating the speech energy of the bit stream based on the extracted at least one CELP parameter without calculating a linear prediction coding (LPC) filter response energy.

LSP-based speech modification for intelligibility enhancement

Abstract: CELP coders commonly use line spectral pairs (LSP) to represent linear prediction parameters, giving stable filters and efficient coding. However, manipulation of LSPs can alter frequencies within the represented signals. This paper describes two computationally efficient LSP-based processing methods designed to enhance the intelligibility of speech degraded by acoustic interference.

Algebraic code-excited linear prediction speech coding method

Abstract: The method uses the technique of CELP coding with algebraic codebook The search for the CELP excitation includes a calculation of certain components of the covariance matrix U=H T ·H where H denotes a lower triangular Toeplitz matrix formed on the basis of the impulse response of a compound filter made up of synthesis filters and of a perceptual weighting filter The memory-stored components of the covariance matrix are only those of the form U(pos i ,p,pos i ,p) and those of the form U(pos i ,p, pos j ,q), pos i ,p and pos j ,q respectively denoting position i and position j for the pulses p and q in the codes of the algebraic codebook

Wideband coding of speech using a scalable pulse codebook

Abstract: Recent standardization efforts have provided motivation for research in the area of wideband speech coding (50 Hz to 7 kHz). Both the European Telecommunications Standards Institute (ETSI) in conjunction with the Third Generation Partnership Project (3GPP), and the ITU-T are currently in the process of evaluating candidate algorithms at bit rates from around 12 kbps to 32 kbps. This paper describes a code-excited linear prediction (CELP) technique used in the Motorola candidate algorithm that is scalable to a wide range of bit rates, thereby allowing the use of a ubiquitous speech model. Preliminary subjective test results indicate that the technique provides very high quality speech that meets or exceeds all requirements for both the ETSI/3GPP and ITU-T wideband speech standardization efforts.