基于USB攝像頭的嵌入式圖像采集系統(tǒng)的研究與實(shí)現(xiàn).pdf

1、江南大學(xué)碩士學(xué)位論文基于USB攝像頭的嵌入式圖像采集系統(tǒng)的研究與實(shí)現(xiàn)姓名：劉飛申請(qǐng)學(xué)位級(jí)別：碩士專(zhuān)業(yè)：計(jì)算機(jī)應(yīng)用技術(shù)指導(dǎo)教師：張曦煌20080701AbstractAbstractTheprocessofdesigningaimagecapturingsystemwitllaUSBwebcamerabasedonembeddedsystemisdescribedThisimage—capturingsystemcontainsthree

2、modules：USBwebcameradriver，upperimagecapturingmodule，avifile—generatingmoduleAwebcameradriverwhichaimsforUSBwebcamerachipze301plhisdesignedTheflamerateofthedriverisimprovedTherearethreemethodsadoptedinordertoimprovethewe

3、bcameradriver’SframerateFirstlyaccordinglytothecertaincamerachip—zc301plh，thefreespca5xxdriveristrimmedreasonablySecondlydoubleURBalternatecirculationanddoubleframesforbufferingdataandimprovingtheV4Lprotocolareadoptedino

4、rdertoimprovetheperformanceofthedesigneddriverThirdlytheUSBwebcameradriverwedesignedhasmmap0systemcallbutithasnoread()systemcallSotheupperapplicationappliesforimagebymeansofmmapOsystemcallBecausemmap0systemcallcouldmapth

5、edevicememoryspcacewhichbelongstokernelspacetotheusermemoryspace，andthereforereducethetimesofcopyingimagedatabetweenthekernelspaceandtheuserspace，improvetheefficiencyofimagecapturingTheupperimage—capturingprogrammewhicho

6、bservestheimprovedvideoforlinuxstandardTheimprovedvideoforlinuxstandardfollows：firstlydriverconstantlycapturesimagesandbuffersimagedatawithdoubleflamebuffers，andsetsflagwhichisusedformarking‘imagealreadycaptured’whenafra

7、meimageiscaptured；secondlyusermodeprogrammeCanconstantlygrabimagesbygivingonlyonce‘capturingimage’requestandwaitingfortheflag、析thblockingitselfTheavifilegeneratingprogrammeisdesignedItCangenerateanavivideofilebasedonmany

8、jpegfilescapturedbythesystemThentheavivideofilecouldbesavedintheremovedstorageinordertoimplementthevideoreplayAtlast，theimage—capturingsystemwedesignedCanworkstablyundertheconditionof$3C2440AmicroprocessorandalTlllinuxop