Implementation and evaluation of video filtering mechanisms for real-time multicast

摘要

QoS requirements in video multicast services are diverse due to the heterogeneity of the network and clients, and the difference in users' preferences on the requested video quality. In previous work, we have proposed a multicast tree construction algorithm, considering an active network in which active nodes can filter or transcode the video stream, which assists the server to provide various qualities of a video stream to satisfy different quality requirements. In this paper, we implemented and evaluated three filter mechanisms, i.e., frame dropping, low-pass and requantization filters for MPEG-2 video streams intended to realize heterogeneous video multicasting in active networks. We propose heuristic algorithms for those filters to appropriately adjust an incoming video stream to the specified output rate. Through experimentation with MPEG-2 video streams, in which we observe the rate and quality variation of filtered streams, we show that the proposed algorithms are practical and effective in regulating video rate without degrading in excess the perceived video quality.