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.
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01 Jan 2001
TL;DR: This chapter contains sections titled: Introduction Motivation and Background backward-adaptive G728 Codec Schematic Backward- adapting G728 Coding Algorithm Reduced-rate G728-like Codec: Variable-length Excitation Vector The Effects of Long-term Prediction Closed-loop Codebook Training
Abstract: This chapter contains sections titled: Introduction Motivation and Background Backward-adaptive G728 Codec Schematic Backward-adaptive G728 Coding Algorithm Reduced-rate G728-like Codec: Variable-length Excitation Vector The Effects of Long-term Prediction Closed-loop Codebook Training Reduced-rate G728-like Codec: Constant-length Excitation Vector Programmable-rate 8-4 kbps Low-delay CELP Codecs Backward-adaptive Error Sensitivity Issues A Low-delay Multimode Speech Transceiver Chapter Summary
1 citations
09 May 1995
TL;DR: The results show that a CELP coder using TCVQ produces significantly better quality than the same coding using VQ, with reasonable complexity, which can favorably trade coding quality against complexity and/or delay.
Abstract: We describe a systematic procedure to replace vector quantization (VQ) with trellis-coded vector quantization (TCVQ) in existing CELP coders. Following this procedure, we design an 8/16 kbit/s TCVQ CELP coder. We analyze the performance of this method in terms of quality and complexity. Our results show that a CELP coder using TCVQ produces significantly better quality than the same coder using VQ, with reasonable complexity. By modifying the TCVQ CELP coder parameters one can favorably trade coding quality against complexity and/or delay.
1 citations
01 Jan 1993
TL;DR: The leading idea, supported by some preliminary experiments on human perception, is that customers will prefer systems providing images with highly natural speech and also telephone services with wideband speech.
Abstract: Future applications like HDTV video, multimedia, mobile audio-visual, N-ISDN and B-ISDN services will require wideband speech coding (7 KHz bandwidth). The leading idea, supported by some preliminary experiments on human perception, is that customers will prefer systems providing images with highly natural speech and also telephone services with wideband speech.
1 citations
Patent•
04 Aug 1995
TL;DR: In this article, a self correlation expression of a preprocessing in a CELP vocoder for obtaining a standby pitch by the self correlation method of the preprocessing at the time of retrieving the pitch of a sound signal, obtaining the coefficient of a pitch filter against the obtained standby pitch and shortening the conventional pitch retrieval.
Abstract: PURPOSE: To provide a shortening method of the processing time by the self correlation expression of a preprocessing in a CELP vocoder for obtaining a standby pitch by the self correlation method of the preprocessing at the time of retrieving the pitch of a sound signal, obtaining the coefficient of a pitch filter against the obtained standby pitch and shortening the conventional pitch retrieval. CONSTITUTION: The method for grasping a period when the correlation is shown to be high by the self correlation expression of the preprocessing from the sound signal, executing pitch retrieval only to the section and executing pitch retrieval for removing the remaining section from pitch retrieval is provided. The CELP vocoder can be realized on a real time basis as an inexpensive DSP chip with low processing speed by the method. The processing process of calculation quantity reduced at the time of pitch retrieval can be used for the other service function so as to design the economic CELP vocoder.
1 citations
TL;DR: For efficient variable-rate speech coding, Karhunen-Loeve transform based adaptive entropy-constrained vector quantization (KLT-AECVQ) is proposed, which produces superior perceptual quality to KLT-based classified vector quantize that yielded better quality than conventional code excited linear predictive (CELP) codec.
Abstract: For efficient variable-rate speech coding, Karhunen-Loeve transform based adaptive entropy-constrained vector quantization (KLT-AECVQ) is proposed. The proposed method consists of backward-adaptive linear predictive coding (LPC) analysis, KLT estimation based on LPC coefficients, and lattice vector quantization followed by Huffman coding according to KLT statistics. As different statistics in an original-signal domain can be mapped into identical statistics in a KLT domain, only a few classified Huffman codebooks are sufficient to represent KLT-domain source statistics. KLT-AECVQ with 32 Huffman codebooks has comparable rate-distortion performance with theoretically optimal AECVQ with infinite number of Huffman codebooks. KLT-AECVQ also produces superior perceptual quality to KLT-based classified vector quantization (KLTCVQ) that yielded better quality than conventional code excited linear predictive (CELP) codec. Under five-sample delay constraints, KLT-AECVQ has also three times lower complexity than CELP codec.
1 citations