The Recording of Interactive Media Streams Using a Common Framework1

The development of real-time transport protocols for the Internet has been a focus of research for several years. Meanwhile, the Real-Time Transport Protocol (RTP) is a well accepted standard that is widely deployed for the transmission of video and audio streams. The RTP specification, combined with a companion RTP profile, covers common aspects of real-time transmissions of video and audio in various encodings. This enabled the development of RTP recorders which record and play back video and audio streams regardless of a specific media encoding. Interactive media streams with real-time characteristics are now gaining importance rapidly. Examples are the data streams of shared whiteboards, remote Java animations and distributed VRML worlds. In this paper we present a generalized recording service that enables the recording and playback of this new class of media. In analogy to video and audio streams we have defined an RTP profile covering common aspects of the interactive media class. We discuss design principles for this recording service and describe the key mechanisms that allow to randomly access recorded interactive media streams independent of a specific media type and encoding.