Add keyboard shortcuts that will increase/decrease the playback rate for video elements.
// ==UserScript==
// @name Video Element Rate Controller Re-dux
// @namespace https://github.com/mirnhoj/video-element-playbackrate-setter
// @version 1.0
// @description Add keyboard shortcuts that will increase/decrease the playback rate for video elements.
// @include http*://*.youtube.com/*
// @include http*://*.gfycat.com/*
// @include http*://*.vimeo.com/*
// @include https://www.facebook.com/video.php*
// @include https://www.facebook.com/*/videos/*
// @include https://www.kickstarter.com/*
// @require https://cdnjs.cloudflare.com/ajax/libs/big.js/5.1.2/big.js
// @grant none
// ==/UserScript==
/* jshint esversion: 6 */
//
// if you want to extend the functionality of this script to other sites
// besides youtube, add additional @include keys to the metadata block.
//
// if you want to change the default playback rate from 1x, change the line
// "var currentPlaybackRate = 1;" to equal something other than 1, like 1.3 to
// have all videos start playing at an increased speed, or 0.7 to have all
// videos start playing at a decreased speed.
//
// if you want change the granularity of the playback rate adjustment, change
// the line "var speedStep = 0.1;" to equal something other than 0.1, like 0.01
// for more granular adjustments, or 0.25 for less granular adjustments.
var currentPlaybackRate = 1; // default playback rate.
var speedStep = 0.125; // how much to modify speed for each keypress
var displayTimeMilliSec = 1500; // how long to show the current speed indicator in milliseconds
var enhancerExtention = true; // set to false if you aren't using Enhancer for Youtube
var infobox = document.createElement("h1");
infobox.setAttribute("id", "playbackrate-indicator");
infobox.style.position = "absolute";
infobox.style.top = "10%";
infobox.style.right = "10%";
infobox.style.color = "rgba(255, 0, 0, 1)";
infobox.style.zIndex = "99999"; // ensures that it shows above other elements.
infobox.style.visibility = "hidden";
infobox.style.marginTop = "3%";
var timeoutID;
var showDisplay = false;
var pref = "preference-changed";
var eventName = "speed";
if (document.readyState !== "loading") {
onReady(); // Or setTimeout(onReady, 0); if you want it consistently async
} else {
document.addEventListener("DOMContentLoaded", onReady);
}
function setPlaybackRate(rate, showInfobox) {
rate = new Big(rate);
// grab the video elements and set their playback rate.
var videoElement = document.getElementsByTagName("video")[0];
videoElement.playbackRate = rate;
infobox.innerHTML = rate + "x";
// add infobox to dom if it doesn't already exist.
if (videoElement && !document.getElementById("playbackrate-indicator")) {
videoElement.parentElement.appendChild(infobox);
}
// show infobox and update rate indicator.
if (showInfobox) {
infobox.style.visibility = "visible";
// clear out any previous timers and have the infobox hide after the pre-set time period
window.clearTimeout(timeoutID);
timeoutID = window.setTimeout(function() {
infobox.style.visibility = "hidden";
}, displayTimeMilliSec);
showDisplay = false;
}
}
// mimic vlc keyboard shortcuts
function addKeyListener() {
window.addEventListener('keydown', function(event) {
var key = event.key;
var videoElement = document.getElementsByTagName("video")[0];
currentPlaybackRate = videoElement.playbackRate;
switch (key) {
// decrease playback rate if '[' is pressed
case "[":
currentPlaybackRate -= speedStep;
showDisplay = true;
setPlaybackRate(currentPlaybackRate, showDisplay);
break;
// increase playback rate if ']' is pressed
case "]":
currentPlaybackRate += speedStep;
showDisplay = true;
setPlaybackRate(currentPlaybackRate, showDisplay);
break;
}
if (enhancerExtention === true) {
window.postMessage({
enhancerforyoutube: pref,
name: eventName,
value: currentPlaybackRate
}, "*");
}
});
}
// show the current speed display on the video when mouse wheel is rolled on the speed element if using Enhancer For Youtube
function addWheelListener() {
var enhancerToolbar = document.getElementById("enhancer-for-youtube-toolbar");
var enhancerToolbarChildren = enhancerToolbar.children[0].children;
for (var i = 0; i < enhancerToolbarChildren.length ; i++ ) {
if (enhancerToolbarChildren[i].dataset.name === eventName) {
var speedChild = enhancerToolbarChildren[i];
}}
if (speedChild) {
speedChild.addEventListener('wheel', function(event) {
var wDelta = event.wheelDelta < 0 ? 'down' : 'up';
var videoElement = document.getElementsByTagName("video")[0];
currentPlaybackRate = videoElement.playbackRate;
switch (wDelta) {
case "down":
// currentPlaybackRate -= speedStep; // uncomment to actually modify the playback speed
showDisplay = true;
setPlaybackRate(currentPlaybackRate, showDisplay);
break;
case "up":
// currentPlaybackRate += speedStep; // uncomment to actually modify the playback speed
showDisplay = true;
setPlaybackRate(currentPlaybackRate, showDisplay);
break;
}
});
}
}
async function onReady() {
addKeyListener();
if (enhancerExtention === true) {
var i = 0;
do {
await wait(200);
i++
} while (!document.getElementById("enhancer-for-youtube-toolbar") && i < 50);
onExtentionReady(); // Or setTimeout(onReady, 0); if you want it consistently async
}
}
function wait(time) {
return new Promise(resolve => {
setTimeout(() => {
resolve();
}, time);
});
}
function onExtentionReady() {
addWheelListener();
}