☰

Twitch - Live Recoder

Records live Twitch streams directly from the browser

// ==UserScript==
// @name         Twitch - Live Recoder
// @namespace    https://greasyfork.org/ja/users/941284-ぐらんぴ
// @version      2025-08-21
// @description  Records live Twitch streams directly from the browser
// @author       ぐらんぴ
// @match        https://www.twitch.tv/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=twitch.tv
// @grant        none
// @run-at       document-start
// @license      MIT
// ==/UserScript==

let $s = (el) => document.querySelector(el), $sa = (el) => document.querySelectorAll(el), $c = (el) => document.createElement(el)
let recorder, chunks = [], isRecording = false, seconds = 0, timerInterval, log = console.log;

const origAddEventListener = EventTarget.prototype.addEventListener;
EventTarget.prototype.addEventListener = function(type, listener, options) {
    if(type === "loadstart"){
        const recordWrapper = function(e){
            if(location.href == "https://www.twitch.tv/") return;
            record();
        };
        origAddEventListener.call(this, type, recordWrapper, options);
    }
    return origAddEventListener.call(this, type, listener, options);
};

function record(){
    let awaitAddon = setInterval(() => {
        let addon = $s(".player-controls__right-control-group")
        clearInterval(awaitAddon);

        let btn = $c('button');
        btn.textContent = ` [RECORD]`;
        btn.className = "GRMP";
        btn.style.color = "red"; //$s('html.tw-root--theme-light')
        btn.style.cursor = "pointer";
        btn.addEventListener("click", () => {
            const video = $s("video");
            if(!video){
                alert("Video element not found.");
                return;
            }

            if(video.paused || video.readyState < 3){
                video.play().catch(err => console.warn("Video play failed:", err));
            }

            if (!isRecording) {
                try {
                    let stream;
                    let recorderStream;

                    if (navigator.userAgent.indexOf('Firefox') > -1) { // Firefox
                        const audioCtx = new AudioContext();
                        const sourceNode = audioCtx.createMediaElementSource(video);
                        const destinationNode = audioCtx.createMediaStreamDestination();

                        sourceNode.connect(audioCtx.destination); // keep audio playback
                        sourceNode.connect(destinationNode);      // send to recorder

                        stream = video.mozCaptureStream();

                        recorderStream = new MediaStream([
                            ...stream.getVideoTracks(),
                            ...destinationNode.stream.getAudioTracks()
                        ]);
                    } else { // Chrome/Edge
                        recorderStream = video.captureStream();
                    }

                    if (!recorderStream) {
                        alert("Failed to capture stream");
                        return;
                    }

                    recorder = new MediaRecorder(recorderStream);
                    chunks = [];

                    recorder.ondataavailable = e => chunks.push(e.data);
                    recorder.onstop = () => {
                        clearInterval(timerInterval);
                        btn.textContent = ` [RECORD]`;

                        const blob = new Blob(chunks, { type: 'video/webm' });
                        const url = URL.createObjectURL(blob);
                        const a = document.createElement('a');
                        a.href = url;

                        // filename generation logic...
                        const now = new Date();
                        const month = String(now.getMonth() + 1).padStart(2, '0');
                        const day = String(now.getDate()).padStart(2, '0');
                        try {
                            let name = location.pathname.slice(1);
                            let title = $s('[data-a-target="stream-title"]').textContent;

                            if (location.pathname.startsWith('/videos/')) {
                                let videoId = location.pathname.replace('/videos/', '');
                                a.download = $s('h1.tw-title').textContent + "_" + title + "_" + videoId + ".webm";
                            } else {
                                a.download = name + "_" + title + "_" + month + "/" + day + ".webm";
                            }
                        } catch (e) {
                            a.download = name + "_" + month + "/" + day + ".webm";
                        }
                        a.click();
                    };

                    recorder.start();
                    isRecording = true;
                    seconds = 0;
                    btn.textContent = formatTime(seconds);

                    timerInterval = setInterval(() => {
                        seconds++;
                        btn.textContent = formatTime(seconds);
                    }, 1000);

                } catch (e) {
                    alert("Recording failed: " + e);
                }
            }else{
                recorder.stop();
                isRecording = false;
                clearInterval(timerInterval);
                btn.textContent = ` [RECORD]`;
            }
        });
        if(!$s('.GRMP')) addon.appendChild(btn);

        function formatTime(sec){
            const m = String(Math.floor(sec / 60)).padStart(2, '0');
            const s = String(sec % 60).padStart(2, '0');
            return ` [${m}:${s}]`;
        }
    }, 500);
}