Multimedia tele-education - PC based real-time narrowband applications

Multimedia tele-education - PC based real-time narrowband applications

Algra, T.

National Aerospace Laboratory NLR

1994-08-29

After surveying tele-education systems and technology, this study describes the design of a tele-education system which is particularly suitable for the extension of the educational facilities of universities to remote communities. The study is focused on the application of third-world small-scale institutes like the University of the Netherlands Antilles (UNA), Curasao, which is used as a case. On the basis of the specific requirements, limiting conditions, and constraints, a PC-based system has been developed, with as much functionality as possible implemented in software. Interactive media considered are low frame-rate video, audio, and the communication of text, graphics, handwriting, and still pictures via a shared screen. A fast and effective low-frame rate video coding scheme is presented. It achieves acceptable image transfer times for application in real-time tele-education services, where the bandwidths are small to moderate and where a requirement exists for implementation based on standard microcomputer equipment without dedicated hardware. This method includes a novel approach to entropy coding: Modified Tunstall Coding, an improvement of Tunstall's variable-to-fixed-length coding algorithm. It is an attractive choice for software implemented entropy coding in the event of limited alphabet sources with a low entropy. Further, a number of improvements of telewriting systems is proposed in relation to tele-education services, concerning a colour-fill facility, an efficient coding algorithm and a method which supports editing of existing pages. To reduce end-to-end delays of compound pages for the purpose of tele-education, a method referred to as pretransfer is developed. It employs periods of low channel utilisation during the session for automatic transmission of these pages. The above mentioned techniques and solutions have been incorporated in the design of a tele-education system appropriate for narrow bandwidths. The development and implementation of this interactive real-time PC-based multimedia system is described. An initial version was involved in a classroom experiment at the UNA. From the evaluation results it may be concluded that the multimedia concept developed meets the recjuirements and is a viable approach to tele-education in the specific situations aimed at in this study.

Coding
Communication equipment
Education
Graphical user interface
Multimedia
Protocol (computers)
Rpal f-iTDP npPT-arinn
User requirements
Video communication
Teleconferencing
Training devices
Transmission efficiency
Video compression

http://resolver.tudelft.nl/uuid:7b6d7b88-67a4-4af4-8290-03964037c623

Nationaal Lucht- en Ruimtevaartlaboratorium

Campus only

NLR Technical Publication TP 94360 U

Aerospace Engineering Reports

report

(c)1994 National Aerospace Laboratory NLR