Papers in PDF format

1. Introduction
MHEG-5 Delivery in the DAVIC Environment
Chetan Gopal ✷ , Cesar A. C. Teixeira ✷✷ and John F. Buford ✷
Abstract: The Digital Audio-Visual Council (DAVIC), an international consortium, has
published specifications for the components of interactive television (ITV) systems to
interoperate. DAVIC 1.0 requires ISO MHEG part 5 (Multimedia Hypermedia Expert
Group - Coding of Multimedia and Hypermedia information) as a supported content
type at the STB, and uses MPEG2 DSM-CC (Digital Storage Media Command and
Control) as the basis for the interaction protocol between the clients and servers. This
paper is aimed at eliciting the relationship between DAVIC, DSMCC and MHEG and
how ITV can be integrated with the WWW.
The WWW provides a means for users to access media, both discrete (DM) such as text, images, and data
and continuous media (CM) such as video and audio, from various services over the Internet. Today these
media are embedded in HTML documents without synchronization or real-time delivery. There are no
quality of service (QOS) negotiations between the client and the server. The servers are generally stateless
and unaware of client profiles to make such QOS decisions. Several companies including Netscape, Xing
Technologies, and VDOnet extend the httpd server by adding a separate streaming media server. These
servers maintain a separate connection with the client to deliver CM and this connection may involve
transport using a special QOS-aware protocol, for example, RTP (Real-Time Protocol). In the future it is
expected that the introduction of RSVP (resource reservation setup protocol) into the Internet will make it
feasible to support large scale CM use in the Internet. In the meantime, existing solutions are proprietary
and seem suited primarily to intranet deployment. Further, the HTML document model has no notion of
time composition.
The ITV world, generally viewed as a joint activity of computer, entertainment, cable, and phone
companies, has been working on a system specification that would make the main components of an ITV
system interoperable. These components include the Set Top Box (STB), the network service providers,
and the content providers. The first version of this specification, DAVIC 1.0, was released in December
1995, and incorporates a number of existing standards including MPEG-2 systems, MPEG-2 DSM-CC,
and MHEG-5. DAVIC is currently working on a new version of the specification that will include support
for accessing Internet and WWW services, including the ability for the STB to execute Java applets. It is
expected that the Java VM will be integrated with the MHEG-5 engine to permit Java and MHEG content
✷ Distributed Multimedia Systems Lab, Department of Computer Science, University of Massachusetts
Lowell, Lowell, MA 01854; E-mail: {cgopal, buford}@cs.uml.edu
✷✷ Department of Computing, Federal University of S.
Carlos, S. Carlos - SP, Brazil; E-mail:
cesar@dc.ufscar.br