CONTENT ADAPTION FOR A STREAMING ENVIRONMENT ENABLING UNIVERSAL MULTIMEDIA ACCESS Andrew Perkis and Tor Halvorsen Department of Telecommunications, NTNU {andrew,torhalv}@tele.ntnu.no ABSTRACT Universal Multimedia Access (UMA) is about how users can access the same media resources with different terminal equipment and preferences. For this to be enabled the media resources have to be adaptable and flexible according to the users needs, and capabilities. To accomplish this a media delivery architecture has been developed taking advantage of some of the possibilities in the upcoming Multimedia Framework, MPEG-21 A test bed, used for experimentations and developments of MPEG-21, is under development, which models parts of the UMA concept and MPEG-21. The test bed emulates media resource delivery in a streaming environment, with various terminal and network capabilities. The paper describes the test bed concepts and discusses issues on media representation and presentation relating to a streaming media environment 1. INTRODUCTION The development of wireless services as e.g. Universal Mobile Telecommunications System (UMTS), has created a possible demand for access to the same type of media resources from different terminals and a variety of user preferences, and over a multitude of continuously varying network connections. There are a wide variety of different terminals, some examples are cellular phones, personal digital assistants (PDA) and ordinary laptops. These terminals vary widely in their features such as resolution, screen size, computing power and also network access technologies yielding amongst other very different bandwidth resources. This myriad of different combinations requires a technology that will adapt the multimedia content to each individual user, his current terminal capabilities and preferences. This adaptation is most likely to become a critical issue in a near future [1]. This article describes a vision for UMA [2], and a test bed demonstrating some of the capabilities for this vision in media delivery in a streaming environment. 1.1. UMA vision The vision of UMA is to define an architecture that deals with delivery of media resources under various network and user conditions. The system is based on the notation of a media base where the media resources are stored once in its original form. The media resource consists of digital items represented in our experimentation as e.g. a picture or a video clip, and an associated informative description (metadata), which is the core in the adaptation process. Adaptation is done after negotiating with the terminal (user preferences) and network capabilities [3]. This concept is used for validation and demonstration within the newest ISO-WG11 standardisation activity, MPEG-21 The Multimedia Framework [4]. MPEG-21 serves as the architecture for exchanging information and media resources between two generic users, such as a client and server. The developed test bed is used within MPEG- 21 and also serves as the departments media research engine [3]. 2. TEST BED The test bed is a part of the currently ongoing development of the MPEG-21 architecture and system model (MPEG-21-YM) related to media resource delivery in a streaming environment. 2.1. MPEG-21 The MPEG-21 vision is to define a Multimedia Framework to enable transparent and