Topic
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.
Papers published on a yearly basis
Papers
More filters
18 May 1998
TL;DR: Experiments show that the proposed variable rate conjugate structure-algebraic code excited linear prediction coder produces the same speech quality as G.729, at the average bit rate of 4.4 kb/s.
Abstract: In this paper, we propose an efficient variable rate algorithm for G.729. The variable rate algorithm consists of two main subjects, the rate determination algorithm and the design of sub rate coders. For the rate determination, we combine the energy-thresholding method, the phonetic segmentation method and the variable hangover period method. Through the analysis of noise features, a 1 kb/s sub rate coder is designed for coding the background noise signal. Also, we design a 4 kb/s sub rate coder for the unvoiced parts. Experiments show that the proposed variable rate conjugate structure-algebraic code excited linear prediction (CS-ACELP) coder produces the same speech quality as G.729, at the average bit rate of 4.4 kb/s.
5 citations
NEC1
TL;DR: This paper proposes an MP-CELP (multi-pulse based CELP) speech coding at 4 kb/s which significantly improves the mean opinion score (MOS) value and further improvement is still required, except for interference talker condition.
Abstract: This paper proposes an MP-CELP (multi-pulse based CELP) speech coding at 4 kb/s. In MP-CELP, amplitudes or signs of multi-pulse excitation are simultaneously vector quantized (VQ). In order to improve speech quality for background noise conditions, the excitation signal is switched between voiced and unvoiced speech, and the number of pulse is greatly increased for unvoiced speech by restricting pulse locations. Further, in order to improve voiced speech quality, the optimal combination among adaptive codebook lag, pulse location, sign codevector and gain codevector is selected which minimizes distortion by employing delayed-decision search. The subjective evaluation results show that speech quality for 4 kb/s MP-CELP is close to that for ITU-T G.723.1 (6.3 kb/s) and G.729 (8 kb/s) in M-TRS clean speech condition. For background noise conditions, the introduction for the excitation switching and the pulse location restriction significantly improves the mean opinion score (MOS) value by 0.4. However, further improvement is still required, except for interference talker condition.
5 citations
TL;DR: A subjective comparison with vector sum excited linear prediction (VSELP) indicates that the 8 kbps TEC and the VSELP reconstructed speech is about equally preferable.
Abstract: Trellis coded vector quantization (TCVQ) and code-excited linear prediction (CELP) coding are combined to form an efficient low-bit rate speech coding system. The resulting system uses a trellis search to select the synthesis filter excitation sequence, and is referred to as trellis excitation coding (TEC). Simulations are performed for encoding rates of 6.4 and 8 kbps. Informal listening tests indicate that the 8 kbps TEC system has quality roughly between that of 6-bit and 7-bit /spl mu/-law PCM with /spl mu/=255. The 6.4 kbps TEC system provides speech quality between 5-bit and 6-bit /spl mu/-law PCM. A subjective comparison with vector sum excited linear prediction (VSELP) indicates that the 8 kbps TEC and the VSELP reconstructed speech is about equally preferable. >
5 citations
13 Apr 1994
TL;DR: An unrestricted text-to-speech synthesis system for Brazilian Portuguese based on concatenation by rules of basic speech units and a reduced set of speech units is proposed, showing that using this inventory of units it is possible to synthesize highly intelligible speech.
Abstract: An unrestricted text-to-speech synthesis system for Brazilian Portuguese is presented. The system is based on concatenation by rules of basic speech units. A reduced set of speech units (149) is proposed. This set comprises mostly consonant-oral vowel (CV) transitions, which represent crucial acoustic segments in the speech production process. The authors show that using this inventory of units it is possible to synthesize highly intelligible speech for Brazilian Portuguese. A CELP model is used as compression and synthesis structure. >
5 citations
02 Jul 2003
TL;DR: A linear predictive coding procedure is developed to allow its implementation with number theoretic transforms and the use of fermat number transform can reduce the cost of linear predictive algorithm implantation on digital signal processor.
Abstract: This paper is about the reduction of the computational complexity of a speech codec. A linear predictive coding procedure is developed to allow its implementation with number theoretic transforms. The use of fermat number transform can reduce, in a significant way, the cost of linear predictive algorithm implantation on digital signal processor.
5 citations