電機工程學系 ; © 2007 Elsevier-In this paper, we propose a two-pass error-resilience transcoding scheme based on adaptive intra-refresh for inserting error-resilience features to a compressed video at the intermediate transcoder of a three-tier streaming system. The proposed transcoder adaptively adjusts the intra-refresh rate according to the video content and the channel's packet-loss rate to protect the most important macroblocks against packet loss. In this work, we consider the problem of multicast of video to multiple clients having disparate channel-loss profiles. We propose a MINMAX loss rate estimation scheme to determine a single intra-refresh rate for all the clients in a multicast group. For the scenario that a quality variation constraint is imposed on the users, we also propose a grouping method to partition a multicast group of heterogeneous users into a minimal number of subgroups to minimize the channel bandwidth consumption while meeting the quality variation constraint. Experimental results show that the proposed method can effectively mitigate the error propagation due to packet loss as well as achieve fairness among clients in a multicast. [All rights reserved Elsevier]