基于CATV网络视频服务器的数据实时性保证策略

:2004-11-02:(863-306-ZD-01-04-4).:,,1972,,.,,1972,,.,,1978,,;,,1968,,,.CATV1,2,1,1,2,11(,100080)2(,100039)E-mail:[e-mail]:,,.,.PC,.PC,,,PC.:;;:TP391:A:1000-1220(2006)02-0354-05ControlStrategyofDataReal-TimePropertyinVideoServerBasedCATVNetworksMIAOYan-chao1,2,YANGXiao-jun1,ZHOUYing-chao1,2,SUNNing-hui11(InstituteofComputingTechnologyTheChineseAcadenyofScience,Beijing100080,China)2(GraduateSchoolofChineseAcademyofSciences,Beijing100039,China)Abstract:Improvementofcomputerperformanceandincrementofnetworkbandwidth,incompanywithproceedingofvideodatacompressingtechnology,makeitpossibletoprovidedigitvideoservice.OnvideoserversbasedonCATV,thedata'sre-al-timepropertycompletelydependsonvideoserver.Thereal-timepropertyofgeneral-purposePCserver'soutputdataislowsomewhat,andisdifficulttoadapttothevideoserver'sdemand.Thispaperextendsthegeneral-purposePCserverbothinhardwareandsoftwaretodesignadatatransferpolicy.Withthepolicy,real-timedatatransfercanbeguaranteedtosomeex-tent,andconsequentlyavideoserverbasedongeneral-purposePCservercanbeobtained.Keywords:CATV;videoserver;real-timeproperty1,,.[1],.,,.(CableTelevision,CATV)(HybridFiberCoaxial-cable,HFC),,,,.CATV,DVB-C(DigitalVideoBroadcasting-Cable),,4[2].(jitter),.PCLinux/Win32,,.MPEG-2[2](TransportStream,TS),.、,.2CATV1,QAM,,CATV,(),、.PC、Win32/Linux、RAID/SCSI、.DVB-C27220062MINI-MICROSYSTEMSVol.27No.2Feb.2006PCI,ASI(AsynchronousSerialInterface)SPI(SynchronousParallelInterface),1CATVQAM.,,.3[3].2,Th,r,r',r',r'=1Th∫t+Thtr(t)dt(1),Th,(1),.Th,r'r.,,,.,.44.1,Th,.2,3,、,,,.、,.,,.,,..3,,,.4ASI,PCI,4,FPGA(FieldProgrammableGateArray),ASI,ASI.4.23,,,,,:,,,,;,,1,,[4],;,,5532:CATV;,,,,();,,,,,.(ASI),.ASI,.,,,,,,.,,.,,.57.52,100,PCWinNT4.0,,,DVB-C,MPEG-2,.5:T,DMA.,0.5msDMA,40MB/s,8KB.:Pentium166CPU,33MHz、32PCI,WinNT4.0.,,.,PC,,.1:,.:ts:tsN[…]:PCR:pcr-M=(27MHz)×(ts、PCRpcr-apcr-bpkt-apkt-b;pcr-apcr-bpcr-a;pkt-r,PCRpcr-r;whilepkt-bdoΔpcr=Mod(pcr-b-pcr-a+pcr-r,233);//PCR,ModifΔpcr≥pcr-M//1Δpkt=pkt-b-pkt-a+pkt-r;//PCRpcr-r=Mod(Δpcr,pcr-M);//PCRpkt-r=Δpkt×pcr-r/Δpcr;//(Δpcr/pcr-M)(Δpkt-pkt-r),N[…];pcr-a=pcr-b;pkt-a=pkt-b;//endiftsPCRpcr-bpkt-bendwhilepkt-b:pcr-apcr-bpkt-b:PES,188;PCR,[2].5,,,.、VCR.5.1,.,,.::;.,,.,:Tp:,、;Tm:;6532006Tw:,Tw=kw·Tm,kw;T1:,;T2:,,T2=2Tw;T3:,T3=2Tw;Tcp:;.·,,,,6,():6AB:,,TAB=Tp;BC:,TBC=0();CD:,,,TCD=Tcp;DE:,,TDE=Tcp;EF:,,0～Tm;FG:,,Tm;Tp,,.,Ta=2Tcp+2Tm≈2Tm·,,,(6C),,BC,().,.,,,,3,,,T2+T3,Tb=T2+T3+Ta≈4Tw+2TmTm,Tcp,TaTm,T2、T3,Tw,Tp,TbTa.,:(1),,,;(2),.(3).7(Tp),0.012.7:12,0～5,10.:ASI:36Mbit/s:7.52ms:752ms:MPEG-2,3.0Mbit/s::PII333,512M,Linux2.2,、3.008(4Tw).,、,.5.2VCRVCR、、(Seek)/、/,,,VCR.,:5.2.1/3,,,,..,.,Tb;Tm()./,,./,/.,Tb.5.2.27532:CATV.,:(1),,,.(2),,.,().,,,,.、、,Tb.,,,(GroupofPic-ture,GOP).,PCR.5.35.3.1,,I/O、CPU,,.、,、,,.,8,,,,,.,,,,.,,、,.8,()().,,,.,,,.,.,,.5.3.2FIFO,,.,,,,.(,).、,.,,,,.6,PC,.,,.References:[1]ZhongYu-zhuo,XiangZhe,ShenHong:Streammediaandvideoserver[M].Beijing:TsinghuaUniversityPress,2003.[2]ZhongYu-zhuo,QiaoBing-xin,QiWei.ISO/IEC13813[M].Beijing:TsinghuaUniversityPress,1996.[3]YangXiao-jun,MiaoYan-chao,GuoLi-li,SunNing-hui.TransferMethodofDigitalVideoonUnreal-timeOperatingSystem.Contributed,2004.[4]MiaoYan-chao,YangXiao-jun,ZhaoYi,SunNing-hui.De-signofVideoServeronCATVnetwork[M].Microelectronics&Computer.2003,20(6).:[1],,.[M].:,2003.[2],,.-MPEG-2(ISO/IEC13813)[M].:,1996.[3],,,.,,2004.[4],,,.CATV[J].,2003,20(6).8532006