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
13 Sep 1994
TL;DR: The paper deals with the design of a digital acoustic underwater phone prototype and uses a scheme where synchronization and equalization (FSE+DFE) were jointly optimized to achieve a synthesized speech with a quality close to the telephonic one.
Abstract: The paper deals with the design of a digital acoustic underwater phone prototype. Digital techniques allow to achieve a synthesized speech with a quality close to the telephonic one. The input speech signal is compressed down to 5.45 kbit/s using a CELP coder. The bit rate is 6 kbit/s before channel coding and expected to be about 8 kbits/s after channel coding. A QPSK modulation with differential encoding was chosen to transmit the useful signal. For the receiver the authors use a scheme where synchronization and equalization (FSE+DFE) were jointly optimized. The whole system (unidirectional link) has been implemented on single DSPs (Motorola 56001) and tested successfully in a very difficult environment (IFREMER pool). >
20 citations
20 Jun 1999
TL;DR: A wideband (7 kHz) speech coding scheme using code-excited linear prediction (CELP) with mixed time and frequency domain excitation with improved synthesis filter is described.
Abstract: This paper describes a wideband (7 kHz) speech coding scheme using code-excited linear prediction (CELP) with mixed time and frequency domain excitation. The proposed frequency domain innovation can be used alternatively or in parallel to a time domain codebook. In addition an improved synthesis filter is used consisting of a signal dependent combination of a forward adaptive and a backward adaptive (FA/BA) structure. An experimental codec operating at 15.5 or 20.0 kbit/s is demonstrated.
20 citations
06 Sep 2004
TL;DR: In order to improve coding efficiency, not only prediction coefficients of the 3D linear prediction but also motion vectors in all the blocks are iteratively optimized for each frame so that a coding rate of prediction errors can have a minimum.
Abstract: This paper proposes an efficient lossless coding scheme for video signals. The coding scheme utilizes a novel block-adaptive 3D prediction method which predicts a video signal at each pel based on both the current frame and the motion-compensated previous frame. The resulting prediction errors are encoded using a kind of context-adaptive arithmetic coding. In order to improve coding efficiency, not only prediction coefficients of the 3D linear prediction but also motion vectors in all the blocks are iteratively optimized for each frame so that a coding rate of prediction errors can have a minimum. Moreover, a variable block-size motion compensation technique is employed for efficient representation of motion information. Experimental results show that coding rates of the proposed scheme are 18–55% lower than those of the JPEG-LS based intra-frame coding scheme.
20 citations
Patent•
14 Sep 2011
TL;DR: In this article, the spectral coefficients of synthesized signal from CELP core layer are utilized to fulfill spectral gaps in error signal spectrum coefficients from a transform coding layer, and decoded signal spectral coefficients are generated.
Abstract: Provided is an audio encoding device that can suppress degradation of audio quality. Spectral coefficients of synthesized signal from CELP core layer are utilized to fulfill spectral gaps in error signal spectrum coefficients from a transform coding layer. By both spectral coefficients, decoded signal spectral coefficients are generated. The decoded signal spectral coefficients and the input signal spectral coefficients are divided into a plurality of sub bands. In each sub band, the energy of the input signal spectral coefficient corresponding to a zero decoded error signal spectral coefficient is calculated, and the energy of the decoded signal spectral coefficient corresponding to the zero decoding error signal spectral coefficient is calculated, and their energy ratio is calculated and is quantized and transmitted.
20 citations
09 May 1995
TL;DR: A low-complexity CELP (LC-CELP) coder with a complexity as low as 3 MIPS, which achieved slightly higher mean opinion stores than the CCITT 32 kb/s ADPCM and exhibits good performance when tandemed with itself or transcoded with other coders.
Abstract: We present a 16 kb/s CELP coder with a complexity as low as 3 MIPS. The main thrust is to reduce the complexity as much as possible while maintaining toll-quality. This low-complexity CELP (LC-CELP) coder has the following features: (1) fast LPC quantization, (2) 3-tap pitch prediction with efficient open-loop pitch search and predictor tap quantization, (3) backward-adaptive excitation gain, and (4) a trained excitation codebook with a small vector dimension and a small codebook size. Most CELP coders require one full DSP or even two DSP chips to implement in real-time. In contrast, 3 to 6 full-duplex LC-CELP coders can fit into a single DSP chip, since each takes only around 3 MIPS to implement. This coder achieved slightly higher mean opinion stores (MOS) than the CCITT 32 kb/s ADPCM. It also exhibits good performance when tandemed with itself or transcoded with other coders.
20 citations