YouTube 720p

change default YouTube video quality to 720p or highest available below 720p. can be used for other video qualities by changing preferredQuality in the code below.

您需要先安裝使用者腳本管理器擴展,如 TampermonkeyGreasemonkeyViolentmonkey 之後才能安裝該腳本。

您需要先安裝使用者腳本管理器擴充功能,如 TampermonkeyViolentmonkey 後才能安裝該腳本。

您需要先安裝使用者腳本管理器擴充功能,如 TampermonkeyViolentmonkey 後才能安裝該腳本。

您需要先安裝使用者腳本管理器擴充功能,如 TampermonkeyUserscripts 後才能安裝該腳本。

你需要先安裝一款使用者腳本管理器擴展,比如 Tampermonkey,才能安裝此腳本

您需要先安裝使用者腳本管理器擴充功能後才能安裝該腳本。

(我已經安裝了使用者腳本管理器,讓我安裝!)

你需要先安裝一款使用者樣式管理器擴展,比如 Stylus,才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展,比如 Stylus,才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展,比如 Stylus,才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展後才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展後才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展後才能安裝此樣式

(我已經安裝了使用者樣式管理器,讓我安裝!)

// ==UserScript==
// @name         YouTube 720p
// @namespace    http://www.youtube.com/
// @version      1.4.3
// @description  change default YouTube video quality to 720p or highest available below 720p. can be used for other video qualities by changing preferredQuality in the code below.
// @match        http://youtube.com/*
// @match        https://youtube.com/*
// @match        http://www.youtube.com/*
// @match        https://www.youtube.com/*
// @grant        none
// @run-at       document-end
// ==/UserScript==


youtubeOverride = function (unsafeWindow) {
    
    // qualities = ['auto', 'hd1080', 'hd720', 'large', 'medium', 'small', 'tiny'];
    // set the quality desired here:
    preferredQuality = 'hd720';
    // overrideMaxAttempts = 30;
    overrideTryDelay = 1000;
    
    console.log('override script starting');
    if (location.pathname.indexOf("/embed/") === 0) {
        var player = unsafeWindow.yt.player.getPlayerByElement(unsafeWindow.document.getElementById("player"));
        if (player != null) {
            overridePlayer(player);
        } else {
            console.log('cannot get player api');
        }
    } else {
        tryToOverride();
        
        var target = document.getElementById('player');
        var MutationObserver = window.MutationObserver;
        var observer = new MutationObserver(function (mutations) {
            mutations.forEach(function (mutation) {
                if (mutation.target.id === 'player-unavailable')  {
                    console.log('player mutation detected');
                    var player = unsafeWindow.document.getElementById('movie_player');
                    if (player != null) {
                        overridePlayer(player);
                    } else {
                        console.log('cannot get player api2');
                    }
                }
            });
        });
        observer.observe(target, { childList: true, subtree: true });
    }
    
    function getPlayerApi() {
        if (location.pathname.indexOf("/embed/") === 0) {
            var player = unsafeWindow.yt.player.getPlayerByElement(unsafeWindow.document.getElementById("player"));
            return player;
        } else {
        	return unsafeWindow.document.getElementById('movie_player');
        }
    }
        
    function tryToOverride(player) {
        console.log('quality override starting');

        player = player != null ? player : getPlayerApi();

        if (player == null || !('setPlaybackQuality' in player)) {
            console.log('error: setPlaybackQuality not available');
            return false;
        }

        var qualityLevels = player.getAvailableQualityLevels();
        var qualityToSet = null;
        for (var i = 0; i < qualityLevels.length; i++) {
            if (qualityLevels[i].trim().toLowerCase() === preferredQuality) {
                qualityToSet = qualityLevels[i];
                break;
            }
        }
        if (qualityToSet == null) {
            qualityToSet = qualityLevels[0];
        }
        if (qualityToSet == null) {
            console.log('error: no quality levels available');
            return false;
        }
        player.setPlaybackQuality(qualityToSet);
        console.log('set quality to ' + qualityToSet);
        return qualityToSet == player.getPlaybackQuality();
    }
    
    function overridePlayer(player) {
        if (overridePlayer.running) {
            return;
        }
        overridePlayer.running = true;
        
        overrideTimeoutFunc.attempts = 0;
        overrideTimeoutFunc();
        
        function overrideTimeoutFunc() {
            overrideTimeoutFunc.attempts++;
            var success = tryToOverride(player);
            if (!success /*&& overrideTimeoutFunc.attempts < overrideMaxAttempts*/) {
                setTimeout(overrideTimeoutFunc, overrideTryDelay)
            } else {
                overridePlayer.running = false;
            }
        }
    }
};

(function () {
    // inject script into page
    if (this.unsafeWindow != null) {
        youtubeOverride(unsafeWindow);
    } else {
        var scriptElem = document.createElement('script');
        scriptElem.setAttribute('type', 'text/javascript');
        scriptElem.text = '(' + youtubeOverride.toString() + ')(window);';
        
        document.documentElement.appendChild(scriptElem);
        document.documentElement.removeChild(scriptElem);
    }
})();