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An Overlay Multicast Infrastructure for Live/Stored Video Streaming Visual Communication Laboratory Department of Computer Science National Tsing Hua University Outline Live video broadcasting Typical service model Limitations Our goals Overlay multicast infrastructure Our previous works
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An Overlay Multicast Infrastructure for Live/Stored Video Streaming Visual Communication Laboratory Department of Computer Science National Tsing Hua University
Outline • Live video broadcasting • Typical service model • Limitations • Our goals • Overlay multicast infrastructure • Our previous works • Multicast video streaming • Peer-to-peer search & delivery • Scalable video coding
Live Video Broadcasting • Techniques • Live video encoding • Multicast delivery • Commercial products • Windows Media Services (Microsoft) • Real System Server (Real) • QuickTime Streaming Server (Apple)
Service Architecture StreamServer (VOD) Stream Server (Live) Encoder Storage Internet (Live Broadcast) (VOD)
Multicast Routing Tree Client A (10:00) Client B (10:00) Client C (10:00) Client D (10:00)
5, 6, 7, … 1, 2, 3, 4 Common Solution: Prefix Caching • Permanently cache the front part of the video. • Clients request before (the start time + the length of the prefix) can see the entire video program. Prefix cache 1 2 3 4 C1
5 min store the first 5 min Client D (10:05) Multicast + Prefix Caching Client A (10:00) Client B (10:00) 5 min Client C (10:00) (10:05) queue the stream (10:10) read data from the buffer
Limitations • Must know the video source in advance. • Need router support. (IP multicast) • Cannot pass through firewall/NAT. • Users arrive after the system startup time cannot view the front part of the video. • Prefix caching is not perfect.
Scenario: Request & Playback • User input • Service mode (live/on-demand) • Video attributes • Peer-to-peer search • Streaming • Overlay multicast • Payment (?) • By service mode (VOD > live) (from server > from p2p) • By video (popular > unpopular) (bit rate) • By search method (advanced > basic)
Request flow distributed query input : service mode query rules init multicast video stream peer 0 EPG peer 1 Search Player peer 4 meta data P2P peer 3 peer 2
Topics in this project • Overlay multicast • Peer-to-peer infrastructure • Performance optimization • Two-mode multicasting • Live broadcasting (real-time) • On-demand streaming (see the entire video)
Advanced Topics (?) • Advanced electronic program guide • Intelligent search • Personal profile • Ambiguous keyword search • Melody / scene search • Distributed / continuous query • Matchmaker (?) • Meta datas • Creation/collection/distribution • Format (?) (object-based?)
Our Previous Works • On-Demand Multicast Streaming Delivery Platform • Technology and Systems • Peer-to-Peer Streaming Video (Directory Search) • Proxy-based Streaming Video • Multicast streaming platform for layered videos
10:02 10:01 10:02 10:04 10:03 On-Demand Multicast Communications 10:00 10:02 10:00 10:00 10:00 10:00 10:00 Source 10:00 10:04 10:00 10:03 10:00 Node with timing control
5 4 3 2 4 3 2 1 C1 C2 10:04 10:00 Interval Caching • Cache a sliding interval of the video. Caching buffer 2, 1 1 5, 4, 3, 2, 1 4, 3, 2, 1 1
Timing Control Mechanism 10:00 10:00 10:03 10:05 2, 1 7 6 5 4 3 To player D, 10:05 4, 3, 2, 1 To player C, 10:03 To player B, 10:00 7, 6, 5, 4, 3, 2, 1
10:08 10:06 On-Demand Multicast Routing source 10:06 10:03 10:02 10:00 Network • Constructing an on-demand multicast tree • find a routing path • allocate buffers to generate path delay
WWW Playback (with Directory Server) directory server Source 1 3 Proxy 4 7 IE 2 5 8 module.exe 6 module.exe Client
10:00 source client … … … Pi Pj Ps 10:02 Playback (Peer-to-Peer) • find a source • find a routing path • allocate buffers
P2P v.s. Proxy Platform Media Player • Mgmt. GUI • Network Mgmt. • QoS Reservation • Proxy • Protocol • Replacement • Chaining Media Player Video Streaming (HTTP) Video Streaming (HTTP) Virtual File System (Media Query) (Information Delivery) Proxy Selection & Chaining Cache Replacement Network Mgmt. IP Networks IP Networks QoS Proxy-Based Peer-to-Peer
11:32 11:33 11:34 11:35 Fault Handling Source One of the clients faults Auto reconfiguration 11:30 11:30 11:40 11:40 11:43 11:44
aggregated stream 1.5 Mbps Bottleneck = 0.7 Mbps 0.7 Mbps 1.5 Mbps High quality 0.8 Mbps 0.8 Mbps low quality 1.5 Mbps 0.8 Mbps Heterogeneous Network Bandwidth Server
Sender Layer L Lossy Channel … Scheduler Layer 2 Layer 1 Decoder with Error Concealment Receiver End-to-end Layer Subscription with Bandwidth Constraint
filename number of layers GUI (Media Player)