DirectShow/sup TM/ RTP support for adaptivity in networked multimedia applications

Execution of a collaboration application or a distributed game involves many individual multimedia applications that concurrently generate and consume audio and video streams. As the resource requirements of individual streams change and as streams/applications are started or terminated, the amount of available resources may change dynamically. Networked MultiMedia applications must be willing to adapt to these changes by taking advantage of the fact that they can deliver varying levels of service that are acceptable to users. The paper addresses the problem of adding network and host adaptive capability to DirectShow/sup TM/ RTP. DirectShow/sup TM/ is Microsoft's architecture for capture and presentation of multimedia data. DirectShow RTP is a framework that extends the DirectShow architecture, adding support for streaming multimedia data using the RTP protocol. We have extended this framework by adding support for streaming applications which dynamically compensate for varying resource availability on the local host and on the computer networks being used to deliver multimedia data to and from these applications. The lessons learned are useful both to applications and to designers of frameworks used to build such applications.