Solution Seamless automatic media adaptation allows sophisticated responses to mobile delivery challenges

Transcription

1 Motivation Emerging mobile networks and devices present unique challenges for high quality multimedia delivery Challenge: Heterogeneity Differing access technologies Differing network characteristics Differing device capabilities Java performance issues Challenge: Network Congestion Shared network scenarios Unpredictable join / leave Fluctuating network load Challenge: Radio Access Signal interference Propagation problems Uneven network coverage Network handoff

2 specified MinMax specified MinMax specified MinMax Solution Seamless automatic media adaptation allows sophisticated responses to mobile delivery challenges Automatic Media Adaptation User QoS Policy Waiting for events Mobility Event Access network changes RTCP Monitor Event New RTCP report arrived Adaptation Algorithm User Policy Event User changed his Policy Monitoring Results ADAPT VIDEO STREAM WITH PRE-DREFINED ADAPTATION VALUES ESTIMATE NEW ACCESS NETWORK NETWORK STATUS = CONGESTED Calculate smoothed packet loss and estimate NETWORK STATUS NETWORK STATUS = UNLOADED No ADAPT VIDEO STREAM WITH USERS min OR max VALUES Update user policy parameters Estimate USERS PREFERENCE Estimate USERS PREFERENCE Movement Detection Resource Availability DECREASE QUALITY or FRAMERATE ADAPT VIDEO STREAM TO NEW VALUE INCREASE QUALITY or FRAMERATE ADAPT VIDEO STREAM TO NEW VALUE QoS Parameters Codec Selections Filter Selections Seamless Chain Switching Media Processing Chains consist of Codecs, Filter, Packetizer etc. Switching between Chains usually imposes additional degradations Our approach: Seamless switching

3 Seamless vs. Traditional Adaptation Problems: - Data loss during chain teardown & rebuilding - Long adaptation time interrupts stream Advantages: - No loss during chain reconstruction - Reduced adaptation time

4 Traditional Adaptation Loss Time Lost Frames Gap Time : New Chain Set-up time : Old Chain Tear-down time, : Intrinsic Chain Delays

5 Seamless Adaptation Loss Time Lost Frames No loss at all! Gap Time Just codec-intrinsic delay! Overall adaptation time also reduced!

6 Demo Scenario Mobility Event RTCP Monitor Event User P olicy Event U ser c hanged his Polic y New R TC P report arriv ed Acc es s netw ork c hanges W aiting for ev ents Adaptation Algorithm Set ac tual Q Update us er polic y parameters ADAPT VID EO STR EAM W IT H PRE-DR EF INED AD APT AT ION VALUES EST IMATE NEW AC C ESS N ET WORK Calc ulate s moothed pac ket los s and es timate NET WOR K ST AT US specified MinM ax Video Server No N ET WORK STATU S = C ON GESTED N ET WORK STATU S = U NLOAD ED Es timate U SERS PR EF ERENC E Estimate U SERS PR EF ERENC E D EC REASE QUALIT Y or F RAM ER AT E and fram erate specified M inmax Set ac tual Q and fram erate AD APT VIDEO STR EAM T O N EW VALU E ADAPT VID EO STR EAM W IT H U SERS min OR m ax VALU ES Set ac tual Q INC R EASE QUALIT Y or F R AM ER AT E specified MinMax RTP Streaming Adaptation based on RTCP feedback Set ac tual Q and fram erate AD APT VIDEO ST REAM TO NEW VALUE and fram erate Adaptation Algorithm Nistnet Emulator Hotspot Technologies GSM/GPRS/UMTS Adaptive Mobile Device

7 Prototype Implementation Java based adaptive multimedia API Based on Java Media Framework (JMF) Pluggable Adaptation Modules (Frame Filter, Quality, Datarate,, Codec Switch) Reference implementation of Seamless Codec Switcher as a plug-in module Enhanced high-speed switching datasource to enable on-the the-fly format switching to JMF RTP mechanisms. MPEG-4 Packetizer / Depacketizer / Frame Filter (DivX4.12) Optimized Resource Management (multi-threading, threading, event-driven) JMF Native Encoder extensions to allow DivX on-the the-fly parameter changes Transcoding Support NistNet Emulator remote control (Java/C++)

8 Sequential Mode Preliminary Results! CaptureDataSource reading audio from microphone Loss Time [ms] DVI GSM DVI GSM G G MP Average of 10 adaptation cycles (Athlon Thunderbird 750MHz, 256MByte Memory, Windows 2000) G G MP ! Results with FileDataSources are even worse (worst case 3 seconds!) Seamless Mode 148.2! Loss Time is 0ms! Chain Switching Time below 1ms (measurement accuracy) Proposed Approach improves Codec Changes significantly! Zero Loss at Sender (verified( with Packet Sniffer)! Reduced Overall Adaptation Time! Codec Independent! Media Type Independent