Multimode coding: application to CELP

Taniguchi, Tomohiko; Unagami, S.; Gray, Robert M.

doi:10.1109/icassp.1989.266387

Cited by 12 publications

(2 citation statements)

References 4 publications

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“…Although the approach based on DSI has been widely and successfully applied to several types of digital circuit multiplication equipment (DCME), voice storage and packetized voice networks, the emerging request for the prevision of high-quality personal communication services able to support integrated multimedia applications has recently stimulated investigation into more efficient VBR speech compression algorithms based on multimode coding [3] [11][12], such as the so-called Variable Rate CELP (VR-CELP), recently proposed for adoption in UMTS systems [13]. A multimode VBR coder typically improves the spectral efficiency by exploiting, not only the silence periods, but also the diverse characteristics of the speech waveform.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of an ATM multiplexer loaded with VBR traffic generated by multimode speech coders

Beritelli

Lombardo

Palazzo

et al. 1999

IEEE J. Select. Areas Commun.

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Multimode coders are able to exploit the different characteristics of the speech waveform and to take into account the different peculiarities of background noise, thus allowing improvements in both signal reconstruction and network offered load. In this context the Variable Rate CELP (VR-CELP) coding, that is, a multimode VBR coding based on the Code Excited Linear Prediction technique, has been introduced in literature and is currently being considered for use in various applications, especially in the third generation UMTS cellular systems. The target of the paper is to introduce an efficient and accurate framework allowing a network designer to analyze the impact of multimode VBR speech coding on the quality of service provided by a wireless/wired ATM network. In order to capture the coder output characteristics, we propose to model a VR-CELP voice source by using a switched batch Bernoulli process (SBBP). More specifically, three models are introduced and compared in terms of accuracy and simplicity in determining network performance. As a result of the comparison, a four-state model has been chosen as the best trade-off. The model is then used to analytically derive the loss probability and the jitter probability density function of an ATM multiplexer loaded by a number of VR-CELP sources. Finally, the proposed paradigm has been assessed in a case study where we demonstrate that, for a given output ATM link capacity and for a number of telecommunication services involving voice transmission, VR-CELP coding performs better than traditional ON-OFF coding.

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Section: Introductionmentioning

confidence: 99%

Performance analysis of an ATM multiplexer loaded with VBR traffic generated by multimode speech coders

Beritelli

Lombardo

Palazzo

et al. 1999

IEEE J. Select. Areas Commun.

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“…Taniguchi et al [3] , Yong and Gersho [4] and Jayant and Chen [5] have investigated a time-varying bitallocation method to excitation and LPC parameters. A speech production system including the vocal tract and the glottal excitation signal is a non-stationary process.…”

Section: Introductionmentioning

confidence: 99%

CELP coding with an adaptive density pulse excitation model

Miseki

International Conference on Acoustics, Speech, and Signal Processing

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This paper proposes an approach to dynamic bitallocation to excitation vectors to improve the performance of CELP coder. The proposed method is based on an adaptive density pulse (ADP) excitation. By using the ADP, bit-allocation to the excitation vector can be easily varied. Also, the number of samples of excitation can be reduced. In this paper, the effects of the ADP parameters to the synthetic speech quality are discussed. The CELP coder with the ADP (ADP-CELP) is described. The benefit of introducing the ADP excitation model to the CELP coder is evaluated. The segmental SNR gains of the ADP-CELP over the conventional CELP were about 2 dB both at 8 kbps and at 4.8 kbps.

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