Foundations and Trends® in Signal Processing > Vol 3 > Issue 4

A History of Realtime Digital Speech on Packet Networks: Part II of Linear Predictive Coding and the Internet Protocol

Robert M. Gray, Department of Electrical Engineering, Stanford University, USA, rmgray@stanford.edu
 
Suggested Citation
Robert M. Gray (2010), "A History of Realtime Digital Speech on Packet Networks: Part II of Linear Predictive Coding and the Internet Protocol", Foundations and Trends® in Signal Processing: Vol. 3: No. 4, pp 203-303. http://dx.doi.org/10.1561/2000000036

Published: 15 May 2010
© 2010 R. M. Gray
 
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In this article:
1 1966: On-Line Signal Processing and Statistical Speech Coding
2 1967: Maximum Entropy and APC
3 1968: SCRL, the Burg Algorithm, IMPs, and CHI
4 1969: SCRL, PARCOR, LPC, and ARPAnet
5 1970–1971: Early LPC Hardware and SUR
6 1972: Early Efforts Toward Packet Speech
7 1973: USC/ISI and NSC
8 1974: TCP, NVP, and Success
9 1975: PRnet, TSP, Markelisms, Quantization, and Residual/Voice-Excited LP
10 1976: Packet Speech Conferencing, Speak & Spell
11 1977: STI, STU, Packet Speech Patent, IP Separation, and MELP
12 1978: IP, PRnet, and Speak & Spell
13 1979: Satellite Networks
14 1981: NVP-II and Residual Codebook Excitation
15 1982: Voice Through the Internet
16 Epilogue
Acknowledgments
References

Abstract

In December 1974 the first realtime conversation on the ARPAnet took place between Culler-Harrison Incorporated in Goleta, California, and MIT Lincoln Laboratory in Lexington, Massachusetts. This was the first successful application of realtime digital speech communication over a packet network and an early milestone in the explosion of real-time signal processing of speech, audio, images, and video that we all take for granted today. It could be considered as the first voice over Internet Protocol (VoIP), except that the Internet Protocol (IP) had not yet been established. In fact, the interest in realtime signal processing had an indirect, but major, impact on the development of IP. This is the story of the development of linear predictive coded (LPC) speech and how it came to be used in the first successful packet speech experiments. Several related stories are recounted as well.

This is the second part of a two part monograph on linear predictive coding (LPC) and the Internet protocol (IP). The first part presented an introduction to this history and a tutorial on linear prediction and its applications to speech, providing background and context to the technical history of the second part.

DOI:10.1561/2000000036
ISBN: 978-1-60198-348-0
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Table of contents:
Preface
Part I: Linear Prediction and Speech
1: Prediction
2: Optimal Prediction
3: Linear Prediction
4: Autoregressive Modeling
5: Maximum Likelihood
6: Maximum Entropy
7: Minimum Distance and Spectral Flattening
8: Linear Predictive Coding
Part II: History
LPC and IP Introduction
9: 1966: On-Line Signal Processing and Statistical Speech Coding
10: 1967: Maximum Entropy and APC
11: 1968: SCRL, the Burg Algorithm, IMPs, and CHI
12: 1969: SCRL, PARCOR, LPC, and ARPAnet
13: 1970-1971: Early LPC Hardware and SUR
14: 1972: Early Efforts towards Packet Speech
15: 1973: USC/ISI and NSC
16: 1974: TCP, NVP, and Success
17: 1975: PRnet, TSP, Markelisms, quantization, and residual/voice-excited LP
18: 1976: Packet Speech Conferencing, Speak & Spell
19: 1977: STI, STU, Packet Speech Patent, IP Separation, and MELP
20: 1978: IP, PRnet, and Speak & Spell
21: 1979: Satellite Networks
22: 1981: NVP II and Residual Codebook Excitation
23: 1982: Voice through the Internet
24: Epilogue
Acknowledgements
References
Index

Linear Predictive Coding and the Internet Protocol

In December 1974 the first realtime conversation on the ARPAnet took place between Culler-Harrison Incorporated in Goleta, California, and MIT Lincoln Laboratory in Lexington, Massachusetts. This was the first successful application of realtime digital speech communication over a packet network and an early milestone in the explosion of realtime signal processing of speech, audio, images, and video that we all take for granted today. It could be considered as the first voice over Internet Protocol (VoIP), except that the Internet Protocol (IP) had not yet been established. In fact, the interest in realtime signal processing had an indirect, but major, impact on the development of IP. This is the story of the development of linear predictive coded (LPC) speech and how it came to be used in the first successful packet speech experiments. Several related stories are recounted as well. The history is preceded by a tutorial on linear prediction methods which incorporates a variety of views to provide context for the stories. This part is a technical survey of the fundamental ideas of linear prediction that are important for speech processing, but the development departs from traditional treatments and takes advantage of several shortcuts, simplifications, and unifications that come with years of hindsight. In particular, some of the key results are proved using short and simple techniques that are not as well known as they should be, and it also addresses some of the common assumptions made when modeling random signals. Linear Predictive Coding and the Internet Protocol is an insightful and comprehensive review of an underpinning technology of the internet and other packet switched networks. It will be enjoyed by everyone with an interest in past and present real time signal processing on the internet.

 
SIG-036