3 Single layer video streaming Scenario –PCs, set-top boxes and mobile devices may all need to access and provide service for the same content. Problems –Use multiple versions of video content (each encoded at different resolution or visual quality). For example, lower resolution video can be sent to, mobile devices while higher resolution or high quality video is sent to PC or STB players –Peers in different versions will not help each other. –The overall video quality received will not be optimal.
4 Multiple layer video streaming Layered Encoding –A video sequence is divided into multiple non- overlapped bit streams, or layers. –Base Layer Contains the basic data representing the most important features of the video. –Enhancement Layers Contain data that progressively refine the reconstructed video quality. –Layered Dependency The upper layers depend on the lower layers. –Benefit Each peer contribute its maximized bandwidth. Minimize the overall transmission cost
7 Message Flows PUT-LAYER (Put Layer Information) into Tracker GET-LAYER (Get Layer Information) from Tracker PUT-CHUNK (Put Chunk Information) into Tracker GET-PEERLIST (Peer Selection) LAYER-CHANGE (Layer Change) STATISTICS
8 Open issues Data Scheduling –Different strategy with single layer streaming System Performance Metrics –Throughput and Delay –Layer Delivery Ratio –Useless Packets Ratio –Jitter Prevention User Performance Metrics –Start-up Delay Playback Continuity –Playback Delay
9 User Performance Metrics Start-up Delay –PCs and set-top boxes may all need to access and provide service for the same content. Problem –Use multiple versions of video content (each encoded at different resolution or visual quality) –Peers in different versions will not help each other. –The overall video quality received will not be optimal.