macOS 10.10用户，Qt5.4 MediaPlayer路径配置完全教程

在MacOS 10.10, Qt5.4, 使用QML运行一段简单的代码，发现一个奇怪的报错，记录一下，代码如下：

	import QtQuick 2.3
	import QtQuick.Window 2.2
	import QtMultimedia 5.4
	
	ApplicationWindow{
		id: root
		visiable:true
		width:800; height:600
		color:"#1F1F1F"
		MediaPlayer{
			id: player
			source:"qrc:/logo.mp4"// source: "qrc:///logo.mp4"}
		VideoOutput{
			anchors.fill: parent
			source: player
		}
		Component.onCompleted:{
			player.play()}}

出现运行报错：
FigByteFlumeCustomURLOpen signalled err=-12936 (kFigByteFlumeError_BadState) (no provider) at /SourceCache/CoreMedia/CoreMedia-1562.238/Prototypes/FigHTTP/FigByteFlumeCustomURL.c line 1486

查找资料：

发现这个问题在Qt5.5.0版本被修复，主要的问题是：资源文件的路径不被识别

参考：

在Qt5.4版本的解决方式为：引入绝对路径

main.cpp：

QQmlApplicationEngine engine;
engine.rootContext()->setContextProperty("applicationDirPath", QApplication::applicationDirPath());
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

main.qml：

ApplicationWindow{
	id: root
	visiable:true
	width:800; height:600
	color:"#1F1F1F"
	MediaPlayer{
		id: player
		source:"file:///"+ applicationDirPath +"/Logo.mp4"}
	VideoOutput{
		anchors.fill: parent
		source: player
	}
	Component.onCompleted:{
		player.play()}}