youtube-music/plugins/downloader/youtube-dl.js

const { randomBytes } = require("crypto");
const { writeFileSync } = require("fs");
const { join } = require("path");

const downloadsFolder = require("downloads-folder");
const is = require("electron-is");
const filenamify = require("filenamify");

// Browser version of FFmpeg (in renderer process) instead of loading @ffmpeg/ffmpeg
// because --js-flags cannot be passed in the main process when the app is packaged
// See https://github.com/electron/electron/issues/22705
const FFmpeg = require("@ffmpeg/ffmpeg/dist/ffmpeg.min");
const ytdl = require("ytdl-core");

const { createFFmpeg } = FFmpeg;
const ffmpeg = createFFmpeg({
	log: false,
	logger: () => {}, // console.log,
	progress: () => {}, // console.log,
});

const downloadVideoToMP3 = (videoUrl, sendFeedback, sendError, reinit) => {
	sendFeedback("Downloading…");

	let videoName = "YouTube Music - Unknown title";
	let videoReadableStream;
	try {
		videoReadableStream = ytdl(videoUrl, {
			filter: "audioonly",
			quality: "highestaudio",
			highWaterMark: 32 * 1024 * 1024, // 32 MB
		});
	} catch (err) {
		sendError(err);
		return;
	}

	const chunks = [];
	videoReadableStream
		.on("data", (chunk) => {
			chunks.push(chunk);
		})
		.on("progress", (chunkLength, downloaded, total) => {
			const progress = Math.floor((downloaded / total) * 100);
			sendFeedback("Download: " + progress + "%");
		})
		.on("info", (info, format) => {
			videoName = info.videoDetails.title.replace("|", "").toString("ascii");
			if (is.dev()) {
				console.log("Downloading video - name:", videoName);
			}
		})
		.on("error", sendError)
		.on("end", () => {
			const buffer = Buffer.concat(chunks);
			toMP3(videoName, buffer, sendFeedback, sendError, reinit);
		});
};

const toMP3 = async (videoName, buffer, sendFeedback, sendError, reinit) => {
	const safeVideoName = randomBytes(32).toString("hex");

	try {
		if (!ffmpeg.isLoaded()) {
			sendFeedback("Loading…");
			await ffmpeg.load();
		}

		sendFeedback("Preparing file…");
		ffmpeg.FS("writeFile", safeVideoName, buffer);

		sendFeedback("Converting…");
		await ffmpeg.run("-i", safeVideoName, safeVideoName + ".mp3");

		const filename = filenamify(videoName + ".mp3", { replacement: "_" });
		writeFileSync(
			join(downloadsFolder(), filename),
			ffmpeg.FS("readFile", safeVideoName + ".mp3")
		);

		reinit();
	} catch (e) {
		sendError(e);
	}
};

module.exports = {
	downloadVideoToMP3,
};