Investigation of threshold dependence in adaptive vector quantization for image transmission in packet switched networks

Document Type

Conference Proceeding

Publication Date

10-25-1988

Abstract

In heavily congested packet-switched networks, instead of trying, a priory, to predict the load to the network for a particular set of users, a preferred approach may be to endeavor to control the load. In order to effect dynamic control of the network load, the user (video encoder), and the service provider (packet-switched network), must be interactively linked, in marked departure of traditional source - network separation. Moreover, the resulting source-network system must be capable to dynamically adjust the values of the average bit rate (B) and/or distortion (D) of the variable bit rate transmission source. Adaptive vector quantization has been employed to encode the image source with constant local picture quality. An activity index, A, has been used to classify image areas into two groups, active and non-active, according to whether A>T or A- = a+b∗T and D=c + d∗T. The value of has been found to be approximately equal to 4.0 for all images studied, while a, b, c, and d vary with the image and can be initially estimated by sampling. By allowing the determination of the proper operating point value for T, these relations may provide the required "handle" to the source-network sytem to effect dynamic adjustments to the distortion, and thus the average picture quality level, and/or the average bit rate, and thus the source load to the network.

Identifier

85076376881 (Scopus)

Publication Title

Proceedings of SPIE the International Society for Optical Engineering

External Full Text Location

https://doi.org/10.1117/12.969053

e-ISSN

1996756X

ISSN

0277786X

First Page

999

Last Page

1005

Volume

1001

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