Moviecast Project Description
The aim of the project Moviecast is the design and development of an Internet based videoconference solution for mobile devices. The solution will consist purely in software, ready to run on standard devices (PDAs) under current operating systems (e.g. Windows Mobile). All software components will be standard compliant. The result of the project will be a highly optimized software library, which encodes and decodes video streams in real-time and supports user and session mobility as well as secured and optimized mobile group communication.
Moviecast addresses the following subproblems:
- signalling schemes suitable for mobile unicast and multicast communication
- optimized communication overlay scenarios
- transport security
- improvement and implementation of a scalable, highly efficient video codec for mobile devices
- design of a modal and scalable GUI for adaptive displays on mobile devices
Technical Core Components
The mobility stack developed within the scope of Moviecast will consist of a multi-layered software architecture
and is devided in two functional blocks: the point-to-(multi)point conference management and the audio-visual media processor. Description parameters will be provided at first using the Session Description Protocol (SDP) and may be delivered within the network as Internet Media Guides (IMGs).
Session negotiation for conference establishment and continuation under user and device mobility is realized with the aid of the Internet standard Session Initiation Protocol (SIP). Up until now SIP only supports group mobility on an abstract level. Negotiations based on overlay and Source Specific Multicast (SSM) resp. are not considered. Moviecast will supplement SIP to support efficient group communication and - if needed - add signalling about device characteristics and resource allocation.
The second functional block - the audio-visual media processor - particularly includes the media codecs. Part of the project will be the development of a scalable video compression codec software employable on PDAs. Moviecast implements temporally scalable video coding. Concepts and implementations will set up on our available, very fast Base Line H.264 version.
Audio and video streams will be transmitted via the Real-Time Transport Protocol (RTP). With regard to mobility requirements, Moviecast applys RTP protocol elements and components for transport optimization.
The network communication of both functional blocks is based on the TCP/UDP-layer, whereupon an optional transport encryption will be applicable. Beyond TLS Moviecast takes group communication into account, i.e. symmetric keys shared by a group.
Furthermore, a major research block within Moviecast is dedicated to real-time Internet mobility, focussing on next generation Mobile IP (MIPv6) group communication and future accelerating schemes.
The interaction of all components will be verified in a testbed: