Download YouTube Captions

By Tim Smart — Last update Oct 28, 2009 — Installed 3,969 times.
There are 27 previous versions of this script.
// ==UserScript==
// @name           Download YouTube Captions
// @namespace      http://userscripts.org/users/tim
// @include        http://*youtube.com/watch*
// @include        https://*youtube.com/watch*
// @require        http://updater.usotools.co.cc/50003.js
// @require        http://translate.usotools.co.cc/3.jsonp?var=uso_translate
// @author         Tim Smart
// @copyright      2009 Tim Smart
// @license        GNU GPL v3.0 or later. http://www.gnu.org/copyleft/gpl.html
// ==/UserScript==

const PLAYER = unsafeWindow.document.getElementById('movie_player');
const VIDEO_ID = unsafeWindow.yt.getConfig('VIDEO_ID');
var caption_array = [];

function make_timeline( time ) {
	var time_array = [],
		milliseconds = Math.round( time % 1 * 1000 ).toString();
	
	while( 3 > milliseconds.length )
		milliseconds = '0' + milliseconds;

	time_array.push( Math.floor( time / (60 * 60) ) );
	time_array.push( Math.floor( ( time - ( time_array[0] * 60 * 60 ) ) / 60 ) );
	time_array.push( Math.floor( time - ( ( time_array[1] * 60 ) + ( time_array[0] * 60 * 60 ) ) ) );

	Array.forEach(time_array, function(string, i) {
		string = string.toString();

		if ( 1 === string.length )
			time_array[i] = "0" + string;
	});

	return time_array.join(":") + "," + milliseconds;
}

function load_caption( selector ) {
	var caption = caption_array[ selector.selectedIndex - 1 ];
	if ( !caption )
		return;

	GM_xmlhttpRequest({
		method: 'GET',
		url: 'http://video.google.com/timedtext?hl=' + caption.lang_code + '&lang=' + caption.lang_code + '&name=' + caption.name + '&v=' + VIDEO_ID,
		onload:function(xhr) {
			if ( xhr.responseText !== "" ) {
				var captions = new DOMParser().parseFromString( xhr.responseText, "text/xml" ).getElementsByTagName('text'),
					textarea = document.createElement("textarea"),
					srt_output = '',
					lookback = [ false, 0, 0 ];

				Array.forEach(captions, function( caption, i ) {
					if ( lookback[0] === true ) {
						lookback[2] = parseFloat( caption.getAttribute('start'), 10 );
						lookback[0] = false;

						textarea.innerHTML = captions[ i - 1 ].textContent.replace( /</g, "&lt;" ).replace( />/g, "&gt;" );
						srt_output += i + "\n" + make_timeline( lookback[1] ) + ' --> ' + make_timeline( lookback[2] ) + "\n" + textarea.value + "\n\n";
					}

					lookback[1] = parseFloat( caption.getAttribute('start'), 10 );
					if ( caption.getAttribute('dur') )
						lookback[2] = lookback[1] + parseFloat( caption.getAttribute('dur'), 10 );
					else {
						if ( captions[ i + 1 ] ) {
							lookback[0] = true;
							return;
						}
						lookback[2] = make_timeline( PLAYER.getDuration() );
					}

					textarea.innerHTML = caption.textContent.replace( /</g, "&lt;" ).replace( />/g, "&gt;" );
					srt_output += i + "\n" + make_timeline( lookback[1] ) + ' --> ' + make_timeline( lookback[2] ) + "\n" + textarea.value + "\n\n";
				});
				textarea = null;

				GM_openInTab( "data:text/plain;charset=utf-8," + encodeURIComponent( srt_output ) );
			}
			else
				alert("Error: No response from server.");

			selector.options[0].selected = true;
		}
	});
}

function load_captions( select ) {
	GM_xmlhttpRequest({
		method: 'GET',
		url: 'http://video.google.com/timedtext?hl=en&v=' + VIDEO_ID + '&type=list',
		onload: function( xhr ) {
			if ( xhr.responseText === "" ) {
				select.options[0].textContent = uso_translate['no_captions'];
				return;
			}

			var captions = new DOMParser().parseFromString( xhr.responseText, "text/xml" ).getElementsByTagName('track');
			Array.forEach( captions, function( caption ) {
				var option = document.createElement('option'),
					caption_info = {
						name: caption.getAttribute('name'),
						lang_code: caption.getAttribute('lang_code'),
						lang_name: caption.getAttribute('lang_translated')
					};

				caption_array.push( caption_info );
				option.innerHTML = caption_info.lang_name;
				select.appendChild( option );
			} );

			captions = null;

			select.options[0].textContent = uso_translate['download'];
			select.disabled = false;
		}
	});
}

(function() {
	var div = document.createElement('div'),
		select = document.createElement('select'),
		option = document.createElement('option'),
		tabs = document.getElementById('watch-actions-area').getElementsByTagName('div')[0],
		last_element = tabs.getElementsByTagName('div');

	last_element = last_element[ last_element.length - 1 ];

	div.setAttribute( 'style', 'padding-top:5px;' );

	select.id = 'captions_selector';
	select.disabled = true;

	option.textContent = uso_translate['loading'];
	option.selected = true;

	select.appendChild( option );
	select.addEventListener('change', function() {
		load_caption(this);
	}, false);

	div.appendChild( select );
	tabs.insertBefore( div, last_element );

	load_captions( select );
})();