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troubleshooting Question

What is the purpose?

Avatar of max7
max7 asked on
7 Comments1 Solution594 ViewsLast Modified:
Hello Experts,

Attached is a javascript file and I would like someone to, generally, tell me all it's doing and why someone would incorporate this into a website.

I am just learning javascript but from what I can tell, this script:

*determines video formats and their preference
*determines video dimensions within the webpage
*will alert if it can't find a video AND/OR if it has the ability to play a particular video format (not sure on this one)
*determines if certain video formats are not supported by client browser
*loads necessary assets or plugins to play a particular video format

For me, and this may just be my ignorance, if  I don't see why I would go through the all the trouble with determining and prioritizing video formats since I would be the one embedding the video (or serving it) and would know it's format before hand e.g. flash OR quicktime, etc.

What am I missing and why would this script be essential or desirable?
// Movie loading code

var siteBase = "http://mysite.com/";
var formatPriorityOrder = [ 'mov', 'mp4','ogg','flv' ];

var quicktimeFormats = [ 'mov', 'mp4'];
var html5Formats = [ 'ogg' ];
var flashFormats = [ 'flv' ];

//load QuickTime files
document.write('<script src="../../scripts/qt/ac_quicktime.js" type="text/javascript"></script>');
document.write('<script src="../../scripts/qt/qtp_library.js" type="text/javascript"></script>');
document.write('<link href="../../css/qt/qtp_library.css" rel="StyleSheet" type="text/css" />');

function LoadVideo(){
	var vidFormats = "";
	var args = Array.prototype.slice.call(arguments);
	var element = args.shift();
	var vidSrc = args.shift();
	element = $(element);
	var vidWidth = "";
	var vidHeight = "";
	if (args.length == 2){
		vidWidth = args[0];
		vidHeight = args[1];
		element.style.width = vidWidth + "px"; //make passed element the same size as movie
		element.style.height = vidHeight + "px";
		vidWidth = "100%";//element.style.width.sub("px","");
		vidHeight = "100%";//element.style.width.sub("px","");
		element.style.height = "100%";
		element.style.width = "100%";
	if (vidSrc.endsWith(".mov")){ vidFormats = "mov";}
	else if (vidSrc.endsWith(".flv")){ vidFormats = "flv";}
	else if (vidSrc.endsWith(".mp4")){ vidFormats = "mp4";}
	else if (vidSrc.endsWith(".ogg")){ vidFormats = "ogg";}
		//var gettingFormats = true;
		var formatGetter = new Ajax.Request('util/movie.php?vidBaseName=' + vidSrc,
				asynchronous: false,
  				onSuccess: function(response) 
    				if (response.responseText != "NotFound"){
						vidFormats = response.responseText;
						//gettingFormats = false;
						alert("Unable to locate an asset for video " + vidSrc);
	//if (vidFormats == "")
	////	{
	//		while (gettingFormats){
	//			//do nothing
	//			}
	//	}
	handlerAndFormat = determineVidHandler(vidFormats);
	if (handlerAndFormat == "unsupportedFormat"){
		alert(vidSrc + " not available in a format supported by your browser.");
		var useFormat = handlerAndFormat.formatToUse;
		var vidHandler = handlerAndFormat.handler;
		if (! vidSrc.endsWith("." + useFormat)){
			vidSrc = siteBase + vidSrc + "." + useFormat;
		switch (vidHandler)
			case "QuickTime":
			case "HTML5":
				loadHTML5(element, vidSrc,vidWidth,vidHeight);
			case "Flash":
				loadFlash(element, vidSrc,vidWidth,vidHeight);

function determineVidHandler(availFormats){
	var useFormat = "";
	if (availFormats.indexOf(',') > -1){ //more than one format available
		availFormats = availFormats.split(",");

		formatPriorityOrder.each(function(format){ //select a format based on its priority and availablity
			if ( availFormats.lastIndexOf(format) != -1) {
				if (useFormat == ""){
					useFormat = format;
		useFormat = availFormats;
	var vidHandler = "";
	if ( quicktimeFormats.lastIndexOf(useFormat) != -1){ vidHandler = "QuickTime";}
	if ( html5Formats.lastIndexOf(useFormat) != -1){ vidHandler = "HTML5";}
	if ( flashFormats.lastIndexOf(useFormat) != -1){ vidHandler = "Flash";}
	if (vidHandler != ""){
		return { formatToUse : useFormat, handler : vidHandler};
		return "unsupportedFormat";

function loadQuickTime(dstElement, vidSrc, vidWidth, vidHeight){
	var vidName = vidSrc.substring(vidSrc.lastIndexOf("/"));
	vidName = vidName.slice(1,vidName.length-4);
		vidWidth, vidHeight, '',
		//'controller', 'false',
		'autoplay', 'true',
		'bgcolor', 'black',
		'scale', 'aspect',
		'EnableJavaScript', 'True',
		'postdomevents', 'True',
		'emb#NAME' , vidName,
		'obj#id' , vidName);
	var qtObj = eval("document."+vidName);

function loadHTML5(dstElement, vidSrc, vidWidth, vidHeight){
	alert("will load HTML5");

function loadFlash(dstElement, vidSrc, vidWidth, vidHeight){
	alert("will load Flash");

		'558', '329', '',
		'controller', 'true',
		'autoplay', 'true',
		'bgcolor', 'black',
		'scale', 'aspect');