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Media Speed Changer

Enables you to change the speed of video and audio with hotkeys (even if the video is inside an iframe)

目前為 2020-12-31 提交的版本，檢視 最新版本。

// ==UserScript==
// @name			Media Speed Changer
// @description		Enables you to change the speed of video and audio with hotkeys (even if the video is inside an iframe)
// @author			BLBC (github.com/hjk789, greasyfork.org/users/679182-hjk789)
// @copyright		2020+, BLBC (github.com/hjk789, greasyfork.org/users/679182-hjk789)
// @version			1.0
// @homepage		https://github.com/hjk789/Creations/tree/master/Userscripts/Media-Speed-Changer
// @license			https://github.com/hjk789/Creations/tree/master/Userscripts/Media-Speed-Changer#license
// @grant			none
// @include			*
// @namespace https://greasyfork.org/users/679182
// ==/UserScript==

document.onkeyup = function(e)
{
	if		(e.key == "Pause") 		 	 		  changeSpeed(0.25,  "relative")
	else if (e.key == "PrintScreen") 			  changeSpeed(-0.25, "relative")
	else if (e.shiftKey && e.key == "ScrollLock") changeSpeed(1)
	else if (e.key == "ScrollLock") 			  changeSpeed(2.5)
	else if (e.ctrlKey && e.key == "Cancel") 	  changeSpeed(4)  // Ctrl + ScrollLock/Pause = Cancel
	else if (e.ctrlKey && e.key == "Insert") 	  changeSpeed(16)
}

function changeSpeed(value, mode = "absolute")
{
	const medias = document.querySelectorAll("video, audio")

	for (i=0; i < medias.length; i++)
		medias[i].playbackRate = (mode == "absolute" ? value : medias[i].playbackRate + value)

	for (i=0; i < window.frames.length; i++)
		window.frames[i].postMessage("changeSpeed(" + value + ",'" + mode + "')", "*")
}

if (window.self == window.top)
{
	// Workaround for GreaseMonkey's bug of not running inside IFRAMEs. But there are some embeded medias that still won't have the script running in it, 
	// like YouTube's embeds. You'll have to use another script manager, like TamperMonkey.

	if (typeof GM_info != "undefined" && GM_info.scriptHandler == "Greasemonkey")
	{
		setInterval(function()  // For sites that lazy-load the iframes
		{
			const iframes = document.querySelectorAll("iframe")

			for (i=0; i < iframes.length; i++)
			{
				if (/youtube|player|video|\.mp4|audio/.test(iframes[i].src) && !/comments/.test(iframes[i].src))  // Only frames that are likely for media embedding
				{
					const frameParent = iframes[i].offsetParent
					frameParent.innerHTML = frameParent.innerHTML.replace(/(<iframe .+?) src=/, "$1 data=").replace("<iframe ","<object ")  // Change the IFRAME element to an OBJECT element, so that the script can run inside it
				}
			}

		}, 2000)
	}

}
else
{
	window.addEventListener("message", function(e){
		try { eval(e.data) } // Some frames have CSP protection, which throws an error and breaks the script. This try-catch prevents it from breaking.
		catch(e) {}  
	})
}