从本地加载 SRT/VTT 字幕，并将其注入为 YouTube 原生 CC 字幕轨道，不创建独立字幕层，也不隐藏原生字幕层。
// ==UserScript==
// @name YouTube Local Subtitles - Native CC Subtitle Injection
// @name:en YouTube Local Subtitles - Native CC Subtitle Injection
// @name:zh-CN YouTube 本地字幕 - 注入原生CC字幕
// @name:zh-TW YouTube 本地字幕 - 注入原生CC字幕
// @namespace https://github.com/FaQxD233/YouTube-Local-Subtitle-Loader-for-Tampermonkey
// @version 1.2.1
// @description 从本地加载 SRT/VTT 字幕，并将其注入为 YouTube 原生 CC 字幕轨道，不创建独立字幕层，也不隐藏原生字幕层。
// @description:en Load local SRT/VTT subtitles and inject them as a YouTube native CC track without creating a separate subtitle layer or hiding the native subtitle layer.
// @description:zh-CN 从本地加载 SRT/VTT 字幕，并将其注入为 YouTube 原生 CC 字幕轨道，不创建独立字幕层，也不隐藏原生字幕层。
// @description:zh-TW 載入本地 SRT/VTT 字幕，並將其注入為 YouTube 原生 CC 字幕軌道，不建立獨立字幕層，也不隱藏原生字幕層。
// @match https://www.youtube.com/watch*
// @match https://www.youtube.com/*&v=*
// @run-at document-start
// @grant none
// @license MIT
// ==/UserScript==
(function () {
'use strict';
const TRACK_VSS_ID = '.yt-local-subtitle';
const TRACK_LANG = 'yt-local';
const MENU_CLASS = 'tm-local-native-cc-menuitem';
const STATE_KEY = '__ytLocalNativeCcState';
const MESSAGES = {
zh: {
trackName: '本地字幕',
uploadLabel: '上传本地字幕',
notLoaded: '未加载',
countSuffix: '条',
loadedLog: '[本地字幕] 已作为 YouTube 原生 CC 轨道注入:',
countLog: '条目数:',
emptyWarn: '[本地字幕] 没有解析到有效字幕:',
debugPrefix: '[本地字幕:debug]',
},
en: {
trackName: 'Local subtitles',
uploadLabel: 'Upload local subtitles',
notLoaded: 'Not loaded',
countSuffix: 'cues',
loadedLog: '[Local subtitles] Injected as a YouTube native CC track:',
countLog: 'cues:',
emptyWarn: '[Local subtitles] No valid subtitles parsed:',
debugPrefix: '[Local subtitles:debug]',
},
};
const state = window[STATE_KEY] || {
cues: [],
filename: '',
version: 0,
track: null,
retryTimer: null,
fileInput: null,
settingsObserverAttached: false,
initialResponsePatched: false,
xhrPatched: false,
initTimer: null,
adBypassTimer: null,
};
window[STATE_KEY] = state;
function onReady(fn) {
if (document.readyState === 'loading') {
document.addEventListener('DOMContentLoaded', fn, { once: true });
} else {
fn();
}
}
function init() {
ensureLocalTrack();
ensureFileInput();
patchLocalTimedtextXhr();
patchInitialPlayerResponseSetter();
injectKnownPlayerResponses();
setupSettingsObserver();
setupAdBypass();
}
function setupAdBypass() {
if (state.adBypassTimer) return;
state.adBypassTimer = setInterval(() => {
const player = getPlayer();
if (!player || !player.classList || !player.classList.contains('ad-showing')) return;
clickSkipAdButton(player);
fastForwardCurrentAd();
}, 250);
}
function clickSkipAdButton(player) {
const skipButton = player.querySelector(
'.ytp-ad-skip-button, .ytp-ad-skip-button-modern, .ytp-skip-ad-button, button[class*="skip"]'
);
if (skipButton && !skipButton.disabled) skipButton.click();
}
function fastForwardCurrentAd() {
const video = document.querySelector('video.html5-main-video');
if (!video || !Number.isFinite(video.duration) || video.duration <= 0) return;
try { video.playbackRate = Math.max(video.playbackRate || 1, 16); } catch (err) {}
try {
if (video.duration - video.currentTime > 0.5) {
video.currentTime = Math.max(0, video.duration - 0.1);
}
} catch (err) {}
}
function ensureLocalTrack() {
if (!state.track || isLegacyLocalTrack(state.track)) state.track = createLocalCaptionTrack();
if ('captionDataUrl' in state) delete state.captionDataUrl;
}
function isLegacyLocalTrack(track) {
return !!(track && typeof track.baseUrl === 'string' && track.baseUrl.startsWith('data:'));
}
function ensureFileInput() {
if (state.fileInput && document.body && document.body.contains(state.fileInput)) return;
if (!document.body) return;
const input = document.createElement('input');
input.type = 'file';
input.accept = '.srt,.vtt,.txt';
input.style.display = 'none';
input.addEventListener('change', handleFileChange);
document.body.appendChild(input);
state.fileInput = input;
}
function handleFileChange(event) {
const file = event.target.files && event.target.files[0];
event.target.value = '';
if (!file) return;
const reader = new FileReader();
reader.onload = function (ev) {
const text = ev.target && ev.target.result ? String(ev.target.result) : '';
loadLocalSubtitles(text, file.name);
};
reader.readAsText(file, 'utf-8');
}
function loadLocalSubtitles(text, filename) {
const cues = /^\s*WEBVTT/i.test(text) ? parseVtt(text) : parseSrt(text);
cues.sort((a, b) => a.start - b.start);
state.cues = cues;
state.filename = filename || msg('trackName');
state.version += 1;
ensureLocalTrack();
state.track = createLocalCaptionTrack();
injectKnownPlayerResponses();
refreshNativeCaptionTracklist();
updateMenuStatus();
if (cues.length) {
selectLocalTrackWithRetry(4);
console.log(msg('loadedLog'), filename, msg('countLog'), cues.length);
} else {
console.warn(msg('emptyWarn'), filename);
}
}
function createLocalCaptionTrack() {
const displayName = getTrackDisplayName();
return {
baseUrl: getLocalCaptionBaseUrl(),
name: { simpleText: displayName, runs: [{ text: displayName }] },
vssId: TRACK_VSS_ID,
languageCode: TRACK_LANG,
languageName: { simpleText: displayName, runs: [{ text: displayName }] },
isTranslatable: false,
isDefault: false,
trackName: msg('trackName'),
displayName,
rtl: false,
};
}
function createCaptionsBaseUrl() {
const videoId = getVideoId();
const baseUrl = new URL('/api/timedtext', location.origin);
baseUrl.searchParams.set('v', videoId || 'local');
baseUrl.searchParams.set('type', 'track');
return baseUrl.toString();
}
function getLocalCaptionBaseUrl() {
const videoId = getVideoId();
const url = new URL('/api/timedtext', location.origin);
url.searchParams.set('v', videoId || 'local');
url.searchParams.set('lang', TRACK_LANG);
url.searchParams.set('name', msg('trackName'));
url.searchParams.set('fmt', 'json3');
url.searchParams.set('local_subtitle', '1');
url.searchParams.set('version', String(state.version));
return url.toString();
}
function patchLocalTimedtextXhr() {
if (state.xhrPatched || typeof XMLHttpRequest === 'undefined') return;
const originalOpen = XMLHttpRequest.prototype.open;
const originalSend = XMLHttpRequest.prototype.send;
XMLHttpRequest.prototype.open = function patchedOpen(method, url) {
this._tmLocalSubtitleUrl = isLocalTimedtextUrl(url) ? String(url) : '';
return originalOpen.apply(this, arguments);
};
XMLHttpRequest.prototype.send = function patchedSend() {
if (!this._tmLocalSubtitleUrl) return originalSend.apply(this, arguments);
const xhr = this;
const body = makeLocalTimedtextResponse(xhr._tmLocalSubtitleUrl);
defineGetter(xhr, 'readyState', 4);
defineGetter(xhr, 'status', 200);
defineGetter(xhr, 'statusText', 'OK');
defineGetter(xhr, 'responseURL', xhr._tmLocalSubtitleUrl);
defineGetter(xhr, 'responseText', body);
defineGetter(xhr, 'response', body);
setTimeout(() => {
fireXhrEvent(xhr, 'readystatechange');
fireXhrEvent(xhr, 'load');
fireXhrEvent(xhr, 'loadend');
}, 0);
return undefined;
};
state.xhrPatched = true;
}
function isLocalTimedtextUrl(rawUrl) {
if (!rawUrl) return false;
try {
const url = new URL(String(rawUrl), location.origin);
return url.origin === location.origin && url.pathname === '/api/timedtext' && url.searchParams.get('local_subtitle') === '1';
} catch (err) {
return false;
}
}
function makeLocalTimedtextResponse(rawUrl) {
let fmt = 'json3';
try {
fmt = (new URL(String(rawUrl), location.origin).searchParams.get('fmt') || 'json3').toLowerCase();
} catch (err) {}
if (fmt === 'srv3' || fmt === 'ttml' || fmt === 'xml') return toYouTubeTranscriptXml(state.cues);
if (fmt === 'vtt' || fmt === 'webvtt') return toWebVtt(state.cues);
return JSON.stringify(toYouTubeJson3(state.cues));
}
function defineGetter(obj, key, value) {
try {
Object.defineProperty(obj, key, { configurable: true, get: () => value });
} catch (err) {}
}
function fireXhrEvent(xhr, type) {
const event = new Event(type);
const handler = xhr['on' + type];
if (typeof handler === 'function') handler.call(xhr, event);
xhr.dispatchEvent(event);
}
function getTrackDisplayName() {
const trackName = msg('trackName');
return state.filename ? `${trackName} (${state.filename})` : trackName;
}
function msg(key) {
const lang = detectUiLanguage();
return (MESSAGES[lang] && MESSAGES[lang][key]) || MESSAGES.en[key] || key;
}
function detectUiLanguage() {
const candidates = [
document.documentElement && document.documentElement.lang,
document.querySelector('html[lang]') && document.querySelector('html[lang]').getAttribute('lang'),
navigator.language,
];
return candidates.some((lang) => /^zh/i.test(String(lang || ''))) ? 'zh' : 'en';
}
function getVideoId() {
try {
return new URL(location.href).searchParams.get('v') || '';
} catch (err) {
return '';
}
}
function patchInitialPlayerResponseSetter() {
if (state.initialResponsePatched) return;
let currentValue = injectIntoPossiblePlayerResponse(window.ytInitialPlayerResponse);
try {
Object.defineProperty(window, 'ytInitialPlayerResponse', {
configurable: true,
get: () => currentValue,
set: (value) => {
currentValue = injectIntoPossiblePlayerResponse(value);
},
});
state.initialResponsePatched = true;
} catch (err) {}
}
function injectKnownPlayerResponses() {
injectIntoPossiblePlayerResponse(window.ytInitialPlayerResponse);
const player = getPlayer();
if (player && typeof player.getPlayerResponse === 'function') {
injectIntoPossiblePlayerResponse(player.getPlayerResponse());
}
try {
const ytcfg = window.ytcfg && window.ytcfg.data_;
if (ytcfg && ytcfg.PLAYER_VARS && ytcfg.PLAYER_VARS.raw_player_response) {
injectIntoPossiblePlayerResponse(ytcfg.PLAYER_VARS.raw_player_response);
}
} catch (err) {}
}
function injectIntoPossiblePlayerResponse(value) {
if (!value || typeof value !== 'object' || !state.track) return value;
if (value.videoDetails || value.streamingData || value.playabilityStatus || value.captions) {
ensureCaptionsContainer(value);
injectTracklistRenderer(value.captions.playerCaptionsTracklistRenderer);
}
if (value.playerResponse) {
ensureCaptionsContainer(value.playerResponse);
injectTracklistRenderer(value.playerResponse.captions.playerCaptionsTracklistRenderer);
}
return value;
}
function ensureCaptionsContainer(playerResponse) {
if (!playerResponse.captions) playerResponse.captions = {};
if (!playerResponse.captions.playerCaptionsRenderer) {
playerResponse.captions.playerCaptionsRenderer = { baseUrl: createCaptionsBaseUrl() };
}
if (!playerResponse.captions.playerCaptionsTracklistRenderer) {
playerResponse.captions.playerCaptionsTracklistRenderer = {};
}
}
function injectTracklistRenderer(renderer) {
if (!renderer || !state.track) return;
if (!Array.isArray(renderer.captionTracks)) renderer.captionTracks = [];
const nextTrack = createLocalCaptionTrack();
state.track = nextTrack;
const existingIndex = renderer.captionTracks.findIndex((track) => track && track.vssId === TRACK_VSS_ID);
if (existingIndex >= 0) {
renderer.captionTracks[existingIndex] = nextTrack;
} else {
renderer.captionTracks.push(nextTrack);
}
const trackIndex = renderer.captionTracks.findIndex((track) => track && track.vssId === TRACK_VSS_ID);
ensureAudioTrackReferences(renderer, trackIndex);
if (!Array.isArray(renderer.translationLanguages)) renderer.translationLanguages = [];
if (!renderer.defaultAudioTrackIndex) renderer.defaultAudioTrackIndex = 0;
}
function ensureAudioTrackReferences(renderer, trackIndex) {
if (trackIndex < 0) return;
if (!Array.isArray(renderer.audioTracks) || !renderer.audioTracks.length) {
renderer.audioTracks = [{ captionTrackIndices: [trackIndex], defaultCaptionTrackIndex: trackIndex }];
return;
}
renderer.audioTracks.forEach((audioTrack) => {
if (!Array.isArray(audioTrack.captionTrackIndices)) audioTrack.captionTrackIndices = [];
if (!audioTrack.captionTrackIndices.includes(trackIndex)) audioTrack.captionTrackIndices.push(trackIndex);
if (audioTrack.defaultCaptionTrackIndex == null && state.cues.length) audioTrack.defaultCaptionTrackIndex = trackIndex;
});
}
function refreshNativeCaptionTracklist() {
const player = getPlayer();
if (!player || !state.track) return;
try { player.loadModule && player.loadModule('captions'); } catch (err) {}
try {
const response = typeof player.getPlayerResponse === 'function' ? player.getPlayerResponse() : null;
injectIntoPossiblePlayerResponse(response);
} catch (err) {}
try {
if (typeof player.getOption === 'function' && typeof player.setOption === 'function') {
const tracklist = player.getOption('captions', 'tracklist') || { captionTracks: [] };
injectTracklistRenderer(tracklist);
player.setOption('captions', 'tracklist', tracklist);
debugLog('tracklist refreshed', tracklist.captionTracks && tracklist.captionTracks.length);
}
} catch (err) {}
}
function selectLocalTrackWithRetry(remaining) {
if (state.retryTimer) {
clearTimeout(state.retryTimer);
state.retryTimer = null;
}
refreshNativeCaptionTracklist();
forceCaptionButtonOn();
clearNativeCaptionTrack();
setTimeout(() => {
selectLocalTrack();
pokeVideoClock();
if (remaining > 0) {
state.retryTimer = setTimeout(() => selectLocalTrackWithRetry(remaining - 1), 500);
}
}, 80);
}
function clearNativeCaptionTrack() {
const player = getPlayer();
if (!player) return;
try {
if (typeof player.setOption === 'function') {
player.setOption('captions', 'track', null);
player.setOption('captions', 'track', {});
}
} catch (err) {}
try {
if (typeof player.setSubtitlesTrack === 'function') player.setSubtitlesTrack(null);
} catch (err) {}
}
function selectLocalTrack() {
const player = getPlayer();
if (!player || !state.track) return;
const trackForApi = {
languageCode: TRACK_LANG,
vssId: TRACK_VSS_ID,
trackName: msg('trackName'),
displayName: getTrackDisplayName(),
};
try {
if (typeof player.setOption === 'function') {
player.setOption('captions', 'captionsInitialState', 'CAPTIONS_INITIAL_STATE_ON');
player.setOption('captions', 'enabled', true);
player.setOption('captions', 'track', trackForApi);
player.setOption('captions', 'track', state.track);
debugLog('track selected', state.track);
}
} catch (err) {}
try {
if (typeof player.setSubtitlesTrack === 'function') player.setSubtitlesTrack(state.track);
} catch (err) {}
}
function forceCaptionButtonOn() {
const button = document.querySelector('.ytp-subtitles-button');
if (button && button.getAttribute('aria-pressed') !== 'true') button.click();
}
function pokeVideoClock() {
const video = document.querySelector('video.html5-main-video');
if (!video) return;
try { video.dispatchEvent(new Event('timeupdate')); } catch (err) {}
if (!Number.isFinite(video.duration) || video.duration <= 0 || video.seeking) return;
try {
const nextTime = Math.min(video.duration - 0.05, video.currentTime + 0.001);
if (nextTime > 0 && Math.abs(nextTime - video.currentTime) > 0.0001) {
video.currentTime = nextTime;
}
} catch (err) {}
}
function getPlayer() {
return document.querySelector('#movie_player') || document.querySelector('.html5-video-player');
}
function debugLog() {
console.log(msg('debugPrefix'), ...arguments);
}
function setupSettingsObserver() {
const player = getPlayer();
if (!player) return;
const settingsMenu = player.querySelector('.ytp-settings-menu');
if (!settingsMenu || settingsMenu._tmLocalNativeCcObserverAttached) return;
const observer = new MutationObserver(() => injectUploadMenuItem(settingsMenu));
observer.observe(settingsMenu, { childList: true, subtree: true });
settingsMenu._tmLocalNativeCcObserverAttached = true;
injectUploadMenuItem(settingsMenu);
}
function injectUploadMenuItem(settingsMenu) {
const rootMenu = Array.from(settingsMenu.querySelectorAll('.ytp-panel-menu')).find((menu) => {
const panel = menu.closest('.ytp-panel');
return panel && !panel.querySelector('.ytp-panel-header');
});
if (!rootMenu || rootMenu.querySelector(`.${MENU_CLASS}`)) return;
const item = document.createElement('div');
item.className = `ytp-menuitem ${MENU_CLASS}`;
const label = document.createElement('div');
label.className = 'ytp-menuitem-label';
label.textContent = msg('uploadLabel');
const content = document.createElement('div');
content.className = 'ytp-menuitem-content';
content.textContent = getMenuStatusText();
item.appendChild(label);
item.appendChild(content);
item.addEventListener('click', (event) => {
event.preventDefault();
event.stopPropagation();
ensureFileInput();
state.fileInput && state.fileInput.click();
});
rootMenu.appendChild(item);
}
function updateMenuStatus() {
document.querySelectorAll(`.${MENU_CLASS} .ytp-menuitem-label`).forEach((el) => {
el.textContent = msg('uploadLabel');
});
document.querySelectorAll(`.${MENU_CLASS} .ytp-menuitem-content`).forEach((el) => {
el.textContent = getMenuStatusText();
});
}
function getMenuStatusText() {
if (!state.cues.length) return msg('notLoaded');
return `${state.cues.length} ${msg('countSuffix')}`;
}
function parseSrt(text) {
const lines = text.replace(/\r/g, '').split('\n');
const entries = [];
let i = 0;
while (i < lines.length) {
let line = lines[i].trim();
if (!line) {
i += 1;
continue;
}
if (/^\d+$/.test(line)) {
i += 1;
line = (lines[i] || '').trim();
}
const timeMatch = line.match(/(.+?)\s*-->\s*(.+)/);
if (!timeMatch) {
i += 1;
continue;
}
const start = parseTime(timeMatch[1]);
const end = parseTime(timeMatch[2]);
i += 1;
const textLines = [];
while (i < lines.length && lines[i].trim() !== '') {
textLines.push(cleanCueText(lines[i]));
i += 1;
}
if (end > start && textLines.length) entries.push({ start, end, text: textLines.join('\n') });
}
return entries;
}
function parseVtt(text) {
const lines = text.replace(/\r/g, '').split('\n');
const entries = [];
let i = 0;
while (i < lines.length) {
const line = lines[i].trim();
if (!line || /^WEBVTT/i.test(line) || line.startsWith('NOTE')) i += 1;
else break;
}
while (i < lines.length) {
let line = lines[i].trim();
if (!line) {
i += 1;
continue;
}
if (!line.includes('-->')) {
i += 1;
line = (lines[i] || '').trim();
}
const timeMatch = line.match(/(.+?)\s*-->\s*(.+)/);
if (!timeMatch) {
i += 1;
continue;
}
const start = parseTime(timeMatch[1]);
const end = parseTime(timeMatch[2]);
i += 1;
const textLines = [];
while (i < lines.length && lines[i].trim() !== '') {
textLines.push(cleanCueText(lines[i]));
i += 1;
}
if (end > start && textLines.length) entries.push({ start, end, text: textLines.join('\n') });
}
return entries;
}
function parseTime(raw) {
let text = String(raw || '').trim().split(/[ \t]/)[0].replace(',', '.');
const parts = text.split(':');
let h = 0;
let m = 0;
let s = 0;
if (parts.length === 3) {
h = parseInt(parts[0], 10) || 0;
m = parseInt(parts[1], 10) || 0;
s = parseFloat(parts[2]) || 0;
} else if (parts.length === 2) {
m = parseInt(parts[0], 10) || 0;
s = parseFloat(parts[1]) || 0;
} else {
s = parseFloat(parts[0]) || 0;
}
return h * 3600 + m * 60 + s;
}
function cleanCueText(text) {
return String(text)
.replace(/<\/?(?:font|b|i|u|c|v|ruby|rt|lang)[^>]*>/gi, '')
.replace(/\{\\[^}]+}/g, '')
.trimEnd();
}
function toYouTubeJson3(cues) {
return {
wireMagic: 'pb3',
pens: [],
wsWinStyles: [],
wpWinPositions: [],
events: cues.map((cue) => ({
tStartMs: Math.max(0, Math.round(cue.start * 1000)),
dDurationMs: Math.max(1, Math.round((cue.end - cue.start) * 1000)),
segs: textToJson3Segs(cue.text),
})),
};
}
function toYouTubeTranscriptXml(cues) {
return '<transcript>' + cues.map((cue) => {
const start = formatXmlNumber(cue.start);
const dur = formatXmlNumber(Math.max(0.001, cue.end - cue.start));
return `<text start="${start}" dur="${dur}">${escapeXml(cue.text)}</text>`;
}).join('') + '</transcript>';
}
function formatXmlNumber(value) {
return Number(value || 0).toFixed(3).replace(/\.0+$/, '').replace(/(\.\d*?)0+$/, '$1');
}
function escapeXml(value) {
return String(value || '')
.replace(/&/g, '&')
.replace(/</g, '<')
.replace(/>/g, '>')
.replace(/"/g, '"')
.replace(/'/g, ''')
.replace(/\n/g, ' ');
}
function textToJson3Segs(text) {
const lines = String(text || '').split('\n');
const segs = [];
lines.forEach((line, index) => {
if (index > 0) segs.push({ utf8: '\n' });
segs.push({ utf8: line });
});
return segs.length ? segs : [{ utf8: '' }];
}
function toWebVtt(cues) {
return 'WEBVTT\n\n' + cues.map((cue, index) => {
return `${index + 1}\n${formatVttTime(cue.start)} --> ${formatVttTime(cue.end)}\n${cue.text}`;
}).join('\n\n') + '\n';
}
function formatVttTime(seconds) {
const safe = Math.max(0, seconds || 0);
const h = Math.floor(safe / 3600);
const m = Math.floor((safe % 3600) / 60);
const s = Math.floor(safe % 60);
const ms = Math.round((safe - Math.floor(safe)) * 1000);
return `${pad2(h)}:${pad2(m)}:${pad2(s)}.${String(ms).padStart(3, '0')}`;
}
function pad2(value) {
return String(value).padStart(2, '0');
}
patchLocalTimedtextXhr();
patchInitialPlayerResponseSetter();
injectKnownPlayerResponses();
setupAdBypass();
onReady(init);
window.addEventListener('yt-navigate-start', () => {
state.cues = [];
state.filename = '';
state.track = createLocalCaptionTrack();
updateMenuStatus();
}, true);
window.addEventListener('yt-navigate-finish', () => setTimeout(init, 800), true);
state.initTimer = state.initTimer || setInterval(init, 3000);
})();