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Application Level Hand-off Support for Mobile Media Transcoding Sessions
Roy, Sumit; Shen, Bo; Sundaram, Vijay; Kumar, Raj
HPL-2002-91
Keyword(s): mobility transcoding; streaming media; hand-off
Abstract: Media transcoding can be used to enable mobile devices that have low resolution and low bit-rate capabilities to access content created for stationary, desktop clients with high bandwidth connections. By deploying transcoding servers near the edge of a large network, it becomes possible to support clients with multiple resolutions, while limiting the bandwidth requirements in the core network. In this paper we look at the problem of supporting mobility of such device by seamlessly handing off media transcoding sessions between servers. We explore different hand-off solutions, starting with the transfer of sufficient amount of state so as to produce byte identical streams when compared to the case when there is no hand-off. However it is found that such a scheme introduces a considerable amount of hand-off delay at the client, due to the large amount of data that needs to be transferred. We propose, analyze and experimentally evaluate more efficient hand-off schemes that reduce delay by coarsening the granularity of the hand-off, and relaxing the requirement for byte identical outputs. We find that these scheme introduce no noticeable degradation in the output quality. These hand-off schemes can also be used to provide load-balancing at the transcoder, or for fault tolerance. Notes: Copyright ACM To be published in and presented at the 12th International Workshop on Network and Operating Systems Support for Digital Audio and Video, 12-14 May 2002, Miami Beach, Florida
22 Pages
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