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Proceedings ArticleDOI

Variable-to-fixed rate conversion of narrowband LPC speech

E. Blackman, +2 more
- Vol. 2, pp 409-412
TLDR
Variable data rate LPC speech compression schemes are employed to transmit LPC parameters only when speech characteristics have changed sufficiently since the last transmission, yielding improved speech quality relative to fixed-rate schemes for a given average transmission rate.
Abstract: 
Variable data rate LPC speech compression schemes are employed to transmit LPC parameters only when speech characteristics have changed sufficiently since the last transmission, yielding improved speech quality relative to fixed-rate schemes for a given average transmission rate. Transmission of variable-rate LPC speech over fixed-rate channels is accomplished using transmit and receive buffers, with resulting transmission delays. Development of proper buffer control strategy is essential to minimize losses caused by exhausting either buffer, or by corrective actions, namely, forced or suppressed transmission. Certain aspects of such strategy and their impact on speech quality and data rate are discussed for a narrowband (2400 bps) speech transmission system.

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Citations
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PatentDOI

Speech synthesis system utilizing variable frame rate

Alva E. Henderson, +1 more
- 25 Jan 1982 - 
TL;DR: A frame control circuit accomplishes the foregoing utilization of speech data at a variable frame rate by the speech synthesizer by providing for a variable number of interpolation calculations between adjacent speech frames from last implemented speech data.
Patent

Method and system for encoding digital speech information

Panagiotis E. Papamichalis
TL;DR: In this article, Markov models are applied to quantized speech parameters to represent their time behavior in a probabilistic manner, which is accomplished by representing the quantised speech parameters as finite state machines having predetermined matrices of transitional probabilities from which the conditional probabilities as to the quantization of successive speech data frames are established.
Patent

Variable frame length vocoder

Tetsu Taguchi
TL;DR: In this paper, a variable frame length vocoder extracts a feature vector for each given frame, a predetermined number of frames being defined as a section, and the feature vectors in each section are stored, changes in feature vectors within a section being approximated by a given number of variable time length flat sections with a constant time length portion between adjacent flat sections, adjacent flat segments being interconnected by an inclined section of the same duration.
Patent

Sub-sampled excitation waveform codebooks

Ananthapadamanabhan A. Kandhadai, +2 more
TL;DR: In this paper, a sub-sampled sparse codebook is generated by decimating permissible pulse locations from the codebook track in accordance with the frequency characteristic of the acoustic signal.
Patent

Method of and means for variable-rate coding of LPC parameters

Yeunung Chen, +1 more
TL;DR: In this paper, a signal exhibiting redundancy is transmitted in a reduced bandwidth by performing a linear interpolation over a number of frames, where interpolated coefficients are tested against quantized values to see if they differ by no more than a threshold.
References
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Journal ArticleDOI

Linear prediction: A tutorial review

John Makhoul
TL;DR: This paper gives an exposition of linear prediction in the analysis of discrete signals as a linear combination of its past values and present and past values of a hypothetical input to a system whose output is the given signal.
Journal ArticleDOI

Minimum prediction residual principle applied to speech recognition

F. Itakura
- 01 Feb 1975 - 
TL;DR: A computer system is described in which isolated words, spoken by a designated talker, are recognized through calculation of a minimum prediction residual through optimally registering the reference LPC onto the input autocorrelation coefficients using the dynamic programming algorithm.
Journal ArticleDOI

Quantization properties of transmission parameters in linear predictive systems

R. Viswanathan, +1 more
- 01 Jun 1975 - 
TL;DR: It is concluded that the reflection coefficients are the best set for use as transmission parameters for linear predictive speech compression systems and logarithms of the ratios of normalized errors associated with linear predictors of successive orders are rendered as the optimal quantization parameters.