Supporting VCR Operation in a Mesh-Based P2P VoD System

Supporting user interactivity such as VCR operations is desirable however it introduces extra complexity and overhead into the VoD system. VCR operations such as random seek, rewind, and fast forward change the location of viewing point, the video playback direction, and the video playback speed. In traditional client-server service model, the streaming server adjusts the streaming schedule on the fly and allocates extra server bandwidth to accomodate these interactive operations. In P2P VoD system, an overlay is established among server and users/peers. Peers pull the video content from the server and neighboring peers. The change of viewing location, direction, and speed not only affects the server but also other peers. The neighboring peers may not have the data at the new playback point, or sufficient uplink capacity to support faster playback rate. The available data at the requesting peer is changed due to VCR operations, which may affect neighboring peers' data downloading. In this paper, we investigate the feasibility of supporting VCR operations in PONDER, a mesh-based P2P VoD system. PONDER employs a dual approach that incorporates the mesh-based p2p downloading into the unicast-based VoD. To accommodate VCR operations, PONDER dynamically adjusts the downloading priority based on the interactivity requirements. The measurement-based admission control admits as many users as possible yet achieves good performance level in face of users' interactivities. Initial results show that PONDER can support VCR operations without degrading users' viewing quality.