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1、上海交通大学硕士学位论文VoD系统中的若干问题研究姓名：章政申请学位级别：硕士专业：通信与信息系统指导教师：王嘉20060201摘要下采样转码模块本文提出了针对H.264/AVC的运动矢量下采样的映射关系对于误码掩盖本文提出了一种新型的误码掩盖框架模型这些方法通过实验仿真证明能拥有很好的性能对于调度算法本文提出一种双向链处理方案以平衡服务器负载和延迟关键词H.264/AVCVoD误码掩盖转码IIABSTRACTABSTRACTInrecentyears,withthedevelopmentofcomputer
2、,telecommunicationandnetworktechnology,multimediacommunicationhasbecomesmoreandmoreimportantinoursociety.Asoneofthemajorservicesinthefieldofmultimediacommunication,videoondemand(VoD),whichplaysagreatroleinbusiness,education,entertainment,etc.hasalsobecomesm
3、oreandmorenecessaryinourdailylife.Duetoitsgreatprosperity,VoDisstilloneofthehotspotsinmultimediafield.VoDincludesthreemainparts:codec,networktransmissionandresourceschedule.Codecisresponsibleforcompressingvideosourceseffectivelyandrobustly.Networktransmissi
4、onisresponsibleforphysicaltransportation.ResourcescheduleisaimingatenhancingVoDsystem’scapacity.Thesethreepartsarecloselylinked.Forexample,whenthenetworkbandwidthisrestricted,compressionefficiencywillplayamuchmoreimportantroletogettheamountofdatathroughthel
5、imitedchannel.Thispapermainlyfocusesontheimplementationofstaticresourceschedule,thefastalgorithmoftranscodinganderrorconcealment.Firstly,wemakeabriefintroductionofcurrentVoDsystemsolutions,andanalyzeexistingproblemsinthesesolutions.Adoublechainresourcesched
6、ulesolutionisproposedbasedontypicalschedulesolutions.Afterwhichourunicastandmulticastsolutionswillbedescribedindetail,inthejointprojectwithLeadtekandthejointprojectwithShanghaiscienceandtechnologycommitteerespectively.Secondly,atranscodingmoduleisintroduced
7、intoVoDserver.Basedonfastdownsizingalgorithm,anewtranscodingalgorithmforH.264/AVCisproposed:oldmotionvectors,whichareextractedfromtheformercompressedbitstream,aremappedtogethertoformthenewmotionvectors.Transcodingspeedwillbeimproveddramaticallyasthemostcomp
8、utationalintensivepartofthealgorithm,encoding---motionestimation,isomitted.Finally,AimedattheproblemsencounteredinnetworktransmissionssuchasIIIABSTRACTjitter,bursterrors,etc.,amodebasederrorconcealment
