Abstract

Abstract

Abstract

Abstract
An efficient algorithm for dynamically multiplexing MPEG2 encoded video sources is presented. Sources are grouped into classes regarding different combined levels of spatial detail and amount of movement. Simulations were performed using different associations of sources belonging to distinct classes, different bit rates and GOP structures. The implications associated to a real implementation are analyzed and a modular architecture is proposed. Simulation results are presented and discussed, showing that sequences with higher spatial detail and motion are those which exhibit the higher quality improvements. These results are almost not affected by the non alignment, at GOP level, between video sequences.

Abstract
The explosion of interest in consuming rich multimedia content resulted in a growing demand for technologies that enable seamless access over any network using any terminal without affecting the viewing experience. Scalable Video Coding (SVC) is considered to be one of the key technologies that will improve the accessibility to video resources through adapting them at network nodes or destination node at a negligible computational cost. State-of-the-art video coding technologies enable a comprehensive set of scalability options. However, the trade-off of having such enriched set of scalability options is the reduced compression efficiency and increased encoder/decoder complexity. This trade-off can be mitigated if the encoder has prior knowledge of the scalability options and levels that are actually needed at a given time. It is possible to achieve this goal in a closely monitored system, such as a Virtual Collaboration System (VCS), in which users and their usage environment are known. This paper proposes a framework to determine the scalability options and levels for encoding scalable video for a VCS. Simulation results highlight the benefits of the proposed framework.

Abstract
The MPEG experts are currently developing the MPEG-21 set of standards and this includes a framework and specifications for digital rights management (DRM), delivery of quality of services (QoS) over heterogeneous networks and terminals, packaging of multimedia content and other things essential for the infrastructural aspects of multimedia content distribution. Considerable research effort is being applied to these new developments and the capabilities of MPEG-21 technologies to address specific application areas are being investigated. One such application area is broadcasting, in particular the development of digital TV and its services. In more practical terms, digital TV addresses networking, events, channels, services, programs, signaling, encoding, bandwidth, conditional access, subscription, advertisements and interactivity. MPEG-21 provides an excellent framework of standards to be applied in digital TV applications. Within the scope of this research work we describe a new model based on MPEG-21 and its relevance to digital TV: the digital broadcast item model (DBIM). The goal of the DBIM is to elaborate the potential of MPEG-21 for digital TV applications. Within this paper we focus on a general description of the DBIM, quality of service (QoS) management and metadata filtering, digital rights management and also present use-cases and scenarios where the DBIM's role is explored in detail.