javascriptquicktime.docx

javascriptquicktime.docx

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javascriptquicktime

HowtoUseJavascripttoControlQuicktime（eithersoundorvideo）

byStephenWilson,Professor,ConceptualInformationArtsProgram,ArtDept,SFSU

Javascriptcontrolofsoundandvideoishighlyspecifictothebrowser,theversionofthebrowser,theplug-in, theoperatingsystem,andtheformatofthefileused Writingroutinesthatwillworkacrossallthesevariationsiscomplex. Therearedifferentcodeforembeddingfiles,differentsetsofjavascriptcommandsavailable,anddifferentjavascriptsyntaxforaddressingthefiles. ItisworththeeffortbecauseJavascriptenablesyoutocreateyourownvisualinterfacestomedia（thusnotrelyingonthestandardcontrollers）andtodynamicallycontrolfeaturesofthemediasuchasstart,stop,pause,locationtoplay,volume,etc. TheexamplebelowillustratesuseofQuicktimetocontrolsoundandmovies. Itassumesyouhavetheappropriatequicktimepluginforyourbrowserandoperatingsystem. Seeapple'ssitefordownloadingtheapproriateplug-in. Alsowiththeconstantchangeofbrowsers,theseexamplesmightnotworkwithyoursystem.

UnfortunatelyatthetimeofcompilingthisresourcetherewerenoadequateguidesortutorialsforusingJavascripttocontrolquicktime. EvenApple'ssitewassketchy. Herearesomelinksthatmightbeuseful:

∙Infoartsgeneralguideonhowtoauthorwebpagesthatincludesound

∙InfoArtsquickguidetoQuickTimeontheWeb

∙InfoartshowtoguidelistingoflinkstoappleandothertuoritalsonQuicktimeandJavascriptcontrolofJavascript

∙InfoartshowtoguidelistingoflinkstoJavascripttutorials

∙InfoartsguideonhowtousejavascripttocontrolNetscape'sLiveAudioplugin（LiveAudiowasthemainplug-inusedbyNetscape tocontrolAudiobutnowotherplug-inshavecomeintoprevalence.）

**LimitationsontheseExamples-NetscapeOnlyforNow-DocumentObjectModels（DOM）

Unfortunately,theexamplesbelowwillonlyworkreliablywithNetscapeNavigator4fornow. IdiosyncraciesintheMacintoshversionofInternetExplorerdevelopmentleftouttheabilityofJavascripttotalktoQuicktimeinExplorer4and5.   FurthermoretheW3organization'sstandardsforaddressingobjectsonapagemeansthattheexamplesherewillprobablynotworkinNetscape6+andExplorer6+ Theauthorwillcontinuetoworkontheproblems.

Theproblemsareworthexploringbecausetheyillustratethecurrentcomplexities. Javascriptrequirestheabilitytoidentifytheobjectinthewebpagethatistobeactedon. ThemethodforindicatingobjectsiscalledtheDocumentObjectModelorDOM. Navigator,Explorer,andtheW3orgallusedifferentmethodsoflocatingobjectsonapage.

ThereareotherapproachespossiblewithInternetExplorer. The bgsoundmethodofembeddingsoundsalsoallowsuseofJavascript. Althoughdetailscannotbeofferedhere,pleasevisitMicrosoftDeveloperNetworkinformationonbgsoundforlistingofpossiblecommands. Also,seeDrJavascript'spagesonuseofactiveXtocontrolaudioinExplorer-EmbeddingSoundinWebPages,PartI:

AudioControlExampleCode-DocJavaScript.Theexamplesbelowshouldbeusefulbecauseuseoftheseotherjavascriptsystemswouldbesimilartowhatispresentedhere.  Althoughitisbeyondthescopeofthistutorial,itmightbepossibletowriteJavascriptfunctionsthatuseddetectionofbrowser,version,andostomakeroutinesthatwouldworkinmostsituations.,

EmbeddingtheQuicktimefileinwebpages.

Differentbrowsersrequiredifferentcommandstoembedfiles. AtthetimeofwritingthispagethenewestInternetExplorerwasusingtheOBJECTtagandNavigatorwasusingtheEMBEDtag. Thecodebelowshouldworkonmostbrowserssinceitusesbothmethods. TheclassidisrequiredbyExplorertoidentifythequicktimeplugin. Thenumberisreference#setbyApplefortheactiveXidentifierforQuicktimeplug-in. Aviewermightneedtodownloadthequicktimeplug-insincemicrosoftquitincludingitautomaticallywiththeIEbrowser.

Theexampleillustratesloadingtwofiles. Oneisamidisoundfilecalled"Jesu-Joy.mid"andtheotherisaquicktimemoviefilecalled"test.mov". Yoursrcwouldneedtoincludethefullorrelativeurlleadingtowhereyourfilesarestored. （2filesareloadedherejustforthesakeofthisexample）. EachfileneedsanameoridassignedbecauseJavascriptwouldneedtheesepropertiestodirectcommands. Theid/nameofthefirstoneisdeclaredtobe"jesu"andthesecondisdeclaredas"test". TheseOBJECTsequencesareplacedwithintheBODYhtmltags. ThisexampleisbasedonresourcesforanAppledeveloperWhat'sNewwebpageonQuicktime.

Theheightandwidthwouldneedtobesetappropriatelyforyourfiles. Alsonotethesettingofthepropertyenablejavascript="true". ThisisrequiredtomakeQuicktimeabletorespondtoJavascriptcommands. Alsoyouneedtotreatthesequicktimefilesasvisualelementsofyourpageandusehtml,styles,tables,etctopositionthemonthepage.Thisexampleplacesthe2filessidebysideina2columntable; otherhtmlpageelementshavebeenomittedintheexamplecode.

LoadingtwofilesbyObjectandEmbedmethod

----（otherhtmlcode）

----

02BF25D5-8C17-4B23-BC80-D3488ABDDC6B"

                     codebase="

                     width="180"height="160"

                     id="jesu">

                     src="jesu-joy.mid"

                     name="jesu"

                     enablejavascript="true"

                     autostart="false">

02BF25D5-8C17-4B23-BC80-D3488ABDDC6B"

                     codebase="

                     width="180"height="160"

                     id="test">

                     src="test.mov"

                     name="test"

                     enablejavascript="true"

                   controller="true"

autostart="false">

----（otherhtmlcode）

----

BuildingLinksorButtonsorImagemapstoactivatetheJavascriptcommands

Hereisasampleofthe JavascriptcommandsQuicktimeunderstands:

 movnameisthenameassignedwiththeobjectorembedloadedthefile.

∙movname.Play（）

∙movname.Stop（）

∙movname.rewind（）

∙movname.SetRate（rate） 1=normalrate; 2+=quickspeed; 0=paused;-1...=backwards

∙movname.SetTime（time） For.movfilestimeisindicatedbynumberofframes-forexamplefora6framepersecondmoviesetTime（30）wouldtakeitto30thframeor5seconds.Forsoundthetimeisindicatedinmiliseconds-forexample,22000（22x1000）wouldtakeitto22thsecond. **notethissettingisdifferentthanthehour:

minute:

second:

framenotationusedintheembedtag.

∙movname.SetVolume（vol）

∙movname.SetStartTime（time）setsstarttimeforloopingusinghours:

minutes:

seconds:

framenotation

∙movname.SetEndTime（time）setsendtimeforloopingusinghours:

minutes:

seconds:

framenotation

ThesecommandscanbeuseddirectlyattachedtolinksorbuttonsorincorporatedintomorecomplexJavascriptfuntions.  Thecommandneedstoreferencethemovieandtheninvokethejavascriptcommand.Themethodofidentifyingthemovieobjectcandifferindifferentbrowsers. Theexamplesbelowillustratereferringbyname"document.jesu"andreferringbythearrayJavascriptkeepsofallobjectsthathavebeenloaded.Snce"jesu"wasthefirstoneloadeditwasthe0thitemoftheembedsarray-embeds（0）. Intheseexamples regularHREFhtmlisusedbuttheurlisreplacedwiththecalltojavascript. **Notethereareothercommandsavailable;seetheAppledeveloperWhat'sNewwebpageonQuicktime. Hereisalistofthejavascriptcommandslistedonthatpage.

voidPlay（

voidStop（）

Step（intcount）

SetRate（floatrate）

GetRate（）

SetTime（inttime）

GetTime（）

SetVolume（intvolume）

GetVolume（）

SetMovieName（stringmovieName）

GetMovieName（）

SetMovieID（intmovieID）

GetMovieID（）

SetStartTime（inttime）

GetStartTime（）

 SetEndTime（inttime）

GetEndTime（）

SetIsLooping（booleanloop）

GetIsLooping（）

SetLoopIsPalindrome（booleanloop）

GetLoopIsPalindrome（）

GetMute（）

SetMute（booleanmute）

SetBgColor（stringcolor）

GetBgColor（）

StartingandStopping:

Herearesomelinksthatusethevariousmethodsofaddressingtocausethemoviestostopandstart.

Callinganobject（referencedbyname）methoddirectly

javascript:

document.jesu.Play（）

javascript:

document.jesu.Stop（）

javascript:

document.test.Play（）

javascript:

document.test.Stop（）

Callinganobject（indexedinthedocument"embeds"arraybyindex）methoddirectly

javascript:

document.embeds[0].Play（）

javascript:

document.embeds[0].Stop（）

javascript:

document.embeds[1].Play（）

javascript:

document.embeds[1].Stop（）

Callinganobject（indexedinthedocument"embeds"arraybyname）methoddirectly

javascript:

document.embeds['jesu].Play（）

javascript:

document.embeds['jesu'].Stop（）

javascript:

document.embeds['test'].Play（）

javascript:

document.embeds['test'].Stop（）

Hereisasampleofthecompletehtmlcode

document.jesu.Play（）;">javascript:

document.jesu.Play（）

TheW3orgnewDOMstandardsusethe"getElementByID"toidentifyobjects. Thisstandardhasbeenpartiallyadoptedby