nicokari-downloader-node/src/utils.ts

import { CriUserAgent, UserAgent } from './constants';
import { Parser } from 'm3u8-parser';
import * as crypto from 'crypto';
import fs from 'fs';

type Manifest = {
	allowCache: boolean;
	endList: boolean;
	mediaSequence: number;
	discontinuitySequence: number;
	targetDuration: number;
	discontinuityStarts: number[];
	segments: {
		duration: number;
		uri: string;
		timeline: number;
		key: {
			method: string;
			uri: string;
			iv: Record<string, number>;
		};
	}[];
	mediaGroups: {
		AUDIO: {
			[key: string]: {
				default: string;
				autoselect: boolean;
				uri: string;
			};
		};
		VIDEO: {
			[key: string]: {
				default: string;
				autoselect: boolean;
				uri: string;
			};
		};
		'CLOSED-CAPTIONS': {
			[key: string]: {
				default: string;
				autoselect: boolean;
				uri: string;
			};
		};
		SUBTITLES: {
			[key: string]: {
				default: string;
				autoselect: boolean;
				uri: string;
			};
		};
	};
	playlists: {
		attributes: {
			AUDIO: string;
			'FRAME-RATE': number;
			RESOLUTION: {
				width: number;
				height: number;
			};
			CODECS: string;
			'AVERAGE-BANDWIDTH': string;
			BANDWIDTH: number;
		};
		uri: string;
		timeline: number;
	}[];
};

export function getMediaPair(targetVideoId: string, targetAudioId: string, m3u8: string) {
	const parser = new Parser();
	parser.push(m3u8);
	parser.end();

	const manifest: Manifest = parser.manifest;
	const audio = manifest.mediaGroups.AUDIO[targetAudioId];
	const video = manifest.playlists.find(playlist => playlist.uri.includes(targetVideoId));

	return {
		audio,
		video,
	};
}

export const downloadAesM3u8 = async (url: string, cookie: string) => {
	const m3u8 = await fetch(url, {
		headers: {
			Cookie: cookie,
			'User-Agent': UserAgent,
		},
	}).then(res => res.text());

	const parser = new Parser();
	parser.push(m3u8);
	parser.end();

	const manifest: Manifest = parser.manifest;

	// console.log(JSON.stringify(manifest, null, 2));

	const initSegment = await fetch(manifest.segments[0].map.uri, {
		headers: {
			Cookie: cookie,
			'User-Agent': UserAgent,
		},
	}).then(res => res.arrayBuffer());

	const iv = Buffer.alloc(Object.keys(manifest.segments[0].key.iv).length * 4);

	for (const key in manifest.segments[0].key.iv) {
		iv.writeUInt32BE(manifest.segments[0].key.iv[key], parseInt(key) * 4);
	}

	const key = await fetch(manifest.segments[0].key.uri, {
		headers: {
			Cookie: cookie,
			'User-Agent': UserAgent,
		},
	}).then(res => res.arrayBuffer());

	const decipher = crypto.createDecipheriv('aes-128-cbc', Buffer.from(key), iv);

	const segments: Buffer[] = [];

	segments.push(Buffer.from(initSegment));

	let i = 0;

	for (const segment of manifest.segments) {
		const res = await fetch(segment.uri, {
			headers: {
				Cookie: cookie,
				'User-Agent': UserAgent,
			},
		});

		const buffer = await res.arrayBuffer();

		const arrayBufferView = new Uint8Array(buffer);

		let  decrypted = decipher.update(arrayBufferView);

		if (i > 0) {
			decrypted = decrypted.subarray(32, decrypted.length)
		}

		fs.writeFileSync(`${i}.mp4`, Buffer.from(decrypted));

		segments.push(decrypted);

		i++;
	}

	segments.push(decipher.final());

	const blob = new Blob(segments, { type: 'video/mp4' });

	return blob.arrayBuffer();
};

export function bufferToHexString(buffer: Buffer) {
	return Array.prototype.map
		.call(buffer, function (x: number) {
			return ('00' + x.toString(16)).slice(-2);
		})
		.join('');
}

export function objToUrlParams(obj: Record<string, string | number>) {
	return Object.keys(obj)
		.map(key => `${encodeURIComponent(key)}=${encodeURIComponent(obj[key])}`)
		.join('&');
}

export function objToCookieString(obj: Record<string, string>) {
	return Object.keys(obj)
		.map(key => `${encodeURIComponent(key)}=${encodeURIComponent(obj[key])}`)
		.join('; ');
}

export function cookieStringToObj(cookieString: string) {
	const obj: Record<string, string> = {};

	cookieString.split(';').forEach(cookie => {
		const [key, value] = cookie.trim().split('=');
		obj[key] = value;
	});

	return obj;
}