YouTube Live の遅延を自動的に最小化します
当前为
// ==UserScript==
// @name YouTube Live minimum latency
// @description YouTube Live の遅延を自動的に最小化します
// @namespace https://gitlab.com/sigsign
// @version 0.1.0
// @author Sigsign
// @license MIT or Apache-2.0
// @match https://www.youtube.com/*
// @noframes
// @grant none
// ==/UserScript==
(function () {
'use strict';
function loadPage(fn) {
/**
* YouTube は SPA になっているため load だけではページ遷移を捕捉できない。
* load と yt-page-data-updated を併用するか yt-navigate-finish を使う。
*
* See: https://stackoverflow.com/questions/24297929/
*/
document.addEventListener('yt-navigate-finish', fn, false);
}
function getPlayer() {
return document.querySelector('#movie_player');
}
function getLiveLatency(player) {
const current = Date.now() / 1000;
const time = player.getMediaReferenceTime();
return time ? current - time : 0;
}
function getBufferHealth(player) {
const stats = player.getVideoStats();
if (!stats) {
return;
}
const buffers = stats.vbu;
if (!buffers) {
return;
}
const [buffer] = buffers.split('-').reverse();
const bufferTime = Number(buffer);
const currentTime = Number(stats.vct);
if (isNaN(bufferTime) || isNaN(currentTime)) {
return;
}
return bufferTime - currentTime;
}
const thresholds = {
NORMAL: 6.0,
LOW: 3.0,
ULTRALOW: 1.0,
};
loadPage(() => {
let isAccelerated = false;
const player = getPlayer();
if (!player) {
return;
}
const stats = player.getVideoStats();
if (stats.live !== 'live' && stats.live !== 'dvr' && stats.live !== 'lp') {
return;
}
if (!player.getAvailablePlaybackRates().includes(1.25)) {
return;
}
if (typeof stats.latency_class === 'undefined') {
return;
}
const threshold = stats.live === 'lp' ? 12.5 : thresholds[stats.latency_class];
if (typeof threshold !== 'number') {
return;
}
const video = document.querySelector('video');
if (!video) {
return;
}
const startAcceleration = () => {
const rate = player.getPlaybackRate();
if (rate !== 1.0) {
return;
}
const latency = getLiveLatency(player);
if (stats.live !== 'live' && latency > 180) {
/**
* DVR or プレミア公開、かつ遅延が 3 分以上ある場合、
* ユーザーが自分の意思でシークしていると想定して対象から外す。
*/
return;
}
if (latency > threshold + 0.5) {
player.setPlaybackRate(1.25);
isAccelerated = true;
}
};
const stopAcceleration = () => {
if (!isAccelerated) {
return;
}
const rate = player.getPlaybackRate();
if (rate !== 1.25) {
return;
}
const bufferLimit = stats.latency_class === 'ULTRALOW' ? 0.8 : 0.4;
const buffer = getBufferHealth(player) || 1.0;
const latency = getLiveLatency(player);
if (buffer < bufferLimit || latency < threshold) {
player.setPlaybackRate(1.0);
}
};
const updateFlag = () => {
if (!isAccelerated) {
return;
}
const rate = player.getPlaybackRate();
if (rate !== 1.25) {
isAccelerated = false;
}
};
video.addEventListener('playing', startAcceleration);
video.addEventListener('timeupdate', stopAcceleration);
video.addEventListener('ratechange', updateFlag);
const timer = setInterval(startAcceleration, 120 * 1000);
const eventCleaner = () => {
video.removeEventListener('playing', startAcceleration);
video.removeEventListener('timeupdate', stopAcceleration);
video.removeEventListener('ratechange', updateFlag);
clearInterval(timer);
};
document.addEventListener('yt-navigate-start', eventCleaner, { once: true });
});
}());