Multimedia system

Overview

Fromanarrowsense,amultimediasystemisacomputersystemwithmultimediafunctions;

Fromabroadsense,amultimediasystemisacollectionoftelephone,television,andmedia,Computernetworkisequaltoanintegratedinformationsystem.

Multimediasystemconsistsoftwoparts:1.Multimediahardwaresystem;2.Multimediasoftwaresystem.Thehardwaresystemmainlyincludes:themainconfigurationofthecomputer,variousexternalequipmentandcontrolinterfacecardswithvariousexternalequipment(includingmultimediareal-timecompressionanddecompressioncircuits),andthesoftwaresystemincludesmultimediadriversoftware,multimediaoperatingsystem,andmultimediadataprocessingsoftware,Multimediaauthoringtoolsoftwareandmultimediaapplicationsoftware.

Android'smultimediasystemmainlyincludesJavaframeworklayer,Clanguageframeworklayer(MediaAPI)andOpenCore.TheJavaframeworklayerisconnectedtotheJavaapplicationlayer.BetweentheJavaframeworklayerandtheClanguageframeworklayeristheJavalocalcallpart(MediaJNI).ThecoreoftheClanguagepartoftheAndroidmultimediapartisthemedialibrary,whichmainlyprovidesaframeworkformediaplayersandmediarecorders.ThemedialibraryprovidesaninterfacetotheupperlayerthroughJNI,andthelowerlayerisimplementedthroughPacketVideoandsoon.

Typesofmultimediainformation

Overview

Multimediainformationincludestext,graphics,images,sounds,movies,animations,etc.,inmanydifferentformsanddifferenttypesofmediaDuetothedifferenceincontentandformat,thecorrespondingcontentmanagementandprocessingmethodsarealsodifferent,andthestoragecapacityvariesgreatly.

Text

Textisthemainformofcommunicationbetweenpeopleintherealworldandthemainmediumforinformationexchangebetweenpeopleandcomputers.Incomputers,charactersarerepresentedbybinarycodes,thatis,differentbinarycodesareusedtorepresentdifferentcharacters.CommonlyusedcharactersincludeWesternandChinesecharacters.

(1)Westerncharacterencoding.Incomputers,Westernlanguages​​arerepresentedbyASCII(AmericanStandardCodeforInformationInterchange)codes.TheASCIIcodeincludes128charactersincludingupperandlowercaseEnglishletters,punctuationmarks,Arabicnumerals,mathematicalsymbols,andcontrolcharacters.AnASCIIcodeoccupiesonebyteandiscomposedof7-bitbinarynumbers.

(2)Chinesecharacterencoding.Chinesecharactercodingincludes:Chinesecharacterinputcoding,ChinesecharacterinternalcodeandChinesecharactermodelcode.

①TheinputcodeofChinesecharacters.Westernlanguages​​canbedirectlyinputintothecomputerthroughthekeyboard,whileChinesecharactersaredifferent.TousethekeyboardtoinputChinesecharacters,youmustdesigncorrespondinginputcodingmethodsforChinesecharacters,suchasMicrosoftPinyininputmethod,Wubifontinputmethod,etc.

②Chinesecharacterinternalcode.NomatterwhatcodeisusedtoinputChinesecharacters,eachChinesecharacterisrepresentedinthecomputerbyauniquecode~Chinesecharacterinternalcode,whichisaninternalcodeusedforoperationssuchasstorage,exchange,andretrievalofChinesecharacterinformation.ThecurrentChinesecharacterencodinghastwobytes,threebytesorevenfourbytes.Amongthem,GB231280(Chinesecharactercodefornationalstandardinformationexchange,referredtoasthenationalstandardcode)isatwo-bytecodethatusestwo7-bitbinarynumberstoencodeaChinesecharacter.Inthecomputer,theChinesecharactercodeandtheWesterncodecoexist.Inordertobeabletodistinguisheachother,thenationalstandardcodespecifiesthehighestbitofthetwobytesas1,andthehighestbitofthebyteusedbytheASCIIcodeis0,andthenthesoftware(Orhardware)judgedaccordingtothehighestbitofthebyte.

③Chinesecharactercode.ThefontcodeisaChinesecharacterfontcoderepresentedbyadotmatrix,anditistheoutputformoftheChinesecharacter.AccordingtothedifferentoutputrequirementsofChinesecharacters,thenumberofdotmatrixis​​alsodifferent.SimpleChinesecharactersare16×16dotmatrix,andimprovedChinesecharactersare24×24dotmatrix,32×32dotmatrix,orevenhigher.Therefore,theamountofinformationofthefontdotmatrixis​​verylarge,andthestoragespaceoccupiedisalsoverylarge.Forexample,eachChinesecharacterina16×16dotmatrixoccupies32bytes,whileeachChinesecharacterina32×32dotmatrixoccupies128bytes.

ItcanbeseenthattheinputcodeofChinesecharacters,theinternalcodeofChinesecharacters,andthefontcodearecodesusedforinput,internalprocessing,andoutputincomputersforthreedifferentpurposes.

Thetraditionaltextinputmethodistousethekeyboardforinput.Youcaninputtextdirectlyintothecomputerthroughahandwritinginputdevice,oryoucanautomaticallyrecognizetextthroughopticalsymbolrecognition(OCR)technologyforinput.Theidealinputmethodistousevoicetoinput,sothatthecomputercanunderstandthehumanlanguageandconvertitintotheinternalcode.Atthesametime,thecomputercanpronouncethetextaccordingtothetext,whichtrulyrealizesthe"human-computerdialogue".ThisisexactlythemultimediaTheproblemthattechnologyneedstosolve.

Graphics

Graphsrefertogeometricalfiguresrepresentedbypoints,lines,surfacesandthree-dimensionalspaces.Ingeometry,geometricelementsareusuallyrepresentedbyvectors,sographicsarealsocalledvectorgraphics.Vectorgraphicsarerepresentedbyasetofinstructions.Theseinstructionsareusedtodescribetheshapes,positions,colors,andotherattributesandparametersofthelines,rectangles,circles,arcs,andcurvesthatmakeupapicture.

Image

Animageisamatrixwhoseelementsrepresentapointinspace,calledapixel.Thecolorandbrightnessofeachpixelarerepresentedbybinarynumbers.Thiskindofimageisalsocalledabitmap.Forblackandwhiteimages,itisrepresentedbya1-bitvalue.Forgrayscaleimages,4bits(16graylevels)or8bits(256graylevels)arecommonlyusedtorepresentthebrightnessofacertainpoint,whilecolorimageshavemultipledescriptionmethods.Bitmapimagesaresuitableforimagesthataremoredetailed,richinlevelsandcolors,andcontainalotofdetails.

Sound

Soundisanimportantpartofmultimediainformationandanessentialmediumforexpressingthoughtsandemotions.Thesoundmainlyincludesthreetypes:wavesound,voiceandmusic.Soundisakindofvibrationwave.Wavesoundisthemostgeneralformofsound.Itcontainsallsoundforms.Voiceisawavesoundwithrichlanguageconnotations.Peoplecanabstractandextractspecificcomponentsofspeech.Inordertoachievetheunderstandingofitsmeaning,itisaspecialmediuminsound;musicisasymbolizedsound.Comparedwithspeech,itsformismorestandardized,suchasmusicinmusic,andsheetmusicisthenormofmusic.Formofexpression.

Movies

Thehumaneyehasabiologicalphenomenonof"visualstay",thatis,afterobservingtheobject,theimageoftheobjectwillremainontheretinaoftheeyeforashorttime.Therefore,ifyoucontinuetoplayimagesatasufficientlyfastspeedthatslightlychangethepositionandshapeoftheobjecteachtime,youreyeswillperceivetheobjectincontinuousmotion.Videosystems(suchasmoviesandTV)aredynamicimagesgeneratedbyapplyingthisprinciple.Thispictureiscalledaframe(Frame),whichisthebasicunitthatconstitutesfilmandtelevisioninformation.

Traditionalradioandtelevisionsystemsuseanalogstorage.Toprocessmoviesandtelevisionswithcomputers,analogmoviesmustbeconvertedintodigitalmovies.Thedigitalfilmandtelevisionsystemisaninformationsystemthatrecordscontinuouslychangingimageinformationinadigitalmanner,andcanbeplayedbackunderthecontrolofanapplicationprogram,andevenspecialeffectscanbeaddedthrougheditingoperations.

Animation

Animationissimilartofilmandtelevision.Itconsistsofaframeofstillpicturesarrangedinacertainorder,andeachframeisslightlydifferentfromadjacentframes.Whenplayingcontinuouslyatacertainspeed,thepersistenceofvisionresultsinacontinuousdynamiceffect.

Themaindifferencebetweencomputeranimationandfilmandtelevisionissimilartothedifferencebetweengraphicsandimages,thatis,thewaythatframesaregeneratedisdifferent.Computeranimationistheuseofcomputerstoexpressthebehaviorandactionsofrealobjectsandanalogobjectsovertime.Itisacontinuouspicturedrawnbycomputergraphicstechnology.Itisanimportantbranchofcomputergraphics;whiledigitalfilmandtelevisionmainlyrefertoanalogsignalsources(suchasTelevision,movies,etc.)amixtureofdigitizedimagesandsynchronizedsounds.Inmultimediaapplications,thereisatendencytoconfusecomputeranimationwithdigitalfilmandtelevision.

HypertextandHypermedia

Intoday’sinformationsociety,informationcontinuestoincreaserapidly,andthetypescontinuetogrow.Inadditiontotextandnumbers,graphics,images,sounds,Multimediainformationsuchasfilmandtelevisionhasoccupiedanincreasingproportioninthefieldofinformationprocessing;howtoeffectivelyorganizeandmanagemassivemultimediainformationsothatpeoplecanretrieveandviewithasbecomeanimportanttopic.Theemergenceofhypertext/hypermediatechnologyhasmadethisissueabettersolution,andithasbecomethecoretechnologyofinformationretrievalontheInternet.

Humanmemoryisanetworkstructureconstructedinawayofassociation.Therearemultiplepathsinthenetworkstructure,anddifferentassociationsearcheswillinevitablyleadtodifferentpaths.Thenetworkedinformationstructurecannotbemanagedinthetraditionaltextform,andahigher-levelinformationmanagementtechnology-hypertextmustbeadopted.

Hypertextcanbesimplydefinedasatechnologythatcollects,stores,andbrowsesdiscreteinformation,andestablishesandrepresentstherelationshipbetweeninformation.Conceptually,theinformationthathasbeenformedintothewebisgenerallycalledhypertext,andthesystemthatmanagesandusesitiscalledhypertextsystem.

Hypertexthasanon-linearnetworkstructure.Thisstructurecanlinkrelatedinformationblockstogetheraccordingtotheassociativethinkingmodeofthehumanbrain,throughthe"hotwords"and"hotspots"intheinformationblocks.Waitforthedefinedchaintoopenotherrelatedmediainformationforuserstobrowse.

Withthedevelopmentofmultimediatechnology,inadditiontotext,themediainformationinhypertextcanalsobemultimediainformationsuchassound,graphics,images,andmovies,thusintroducingtheconceptof"hypermedia".Media-Multimedia+Hypertext.Thetwoconceptsof"hypertext"and"hypermedia"aregenerallynotstrictlydistinguished,andcanusuallyberegardedassynonyms.

Thecompositionofthemultimediasystem

1.MultimediahardwaresystemsAtpresent,themostcommonmultimediahardwaresystemsaremultimediapersonalcomputers(MPC)basedontheIBMPCseriesandseriescomputersbasedonAppleMacintosh.

2.MultimediasoftwaresystemSoftwaresystemisthesoulofmultimediatechnology,anditsfunctionistoenableuserstoorganizeandusemultimediadataconvenientlyandeffectively.Multimediasoftwarecanbedividedinto:①systemsoftware,whichisthebasicoperatingsystemofpersonalcomputers,suchasWindowsseriessoftware;②editingsoftware,issoftwareforcollecting,organizingandeditingvariousmediadata,suchaswordprocessingsoftware,Audio-visualprocessingsoftware,etc.;③Creationsoftwareisaprogramusedtointegratemultimediamaterialsandsetinteractivecontrol,includinglanguage-basedcreationsoftwaresuchasVisualBasic,tool-basedcooperationsoftwaresuchasToolBook,etc.;④Multimediaapplicationsoftware,referstoThemultimediaproductscompiledbytheabovesoftware,andthemultimediaproductsusedforteachingarecalledmultimediateachingmaterialsormultimediacourseware.