puppeteerでスクリーンキャプチャを実行する

capture.js

// 
'use strict';


const puppeteer = require('puppeteer');
const { spawn } = require('child_process');
const viewportWidth = 1280; //parseInt(process.argv[4]);
const viewportHeight = (viewportWidth * 9) / 16; //parseInt(process.argv[3]);

const fps = 30;
const ffmpegArgs = (fps) => [
	'-y',
	'-f',
	'image2pipe',
	'-r',
	`${+fps}`,
	'-i',
	'-',
	'-c:v',
	'libx264',
	'-auto-alt-ref',
	'0',
	'-pix_fmt',
	'yuva420p',
	'-metadata:s:v:0',
	'alpha_mode="1"',
];

const write = (stream, buffer) =>
	new Promise((resolve, reject) => {
		stream.write(buffer, (error) => {
			if (error) reject(error);
			else resolve();
		});
	});

// ---------------

(async () => {
	let options = {
		pipeOutput: true,
		output: 'output.mp4',
	};

	const ffmpegPath = 'ffmpeg';
	const args = ffmpegArgs(fps);
	const outfile = options.output;

	args.push(outfile);

	const ffmpeg = spawn(ffmpegPath, args);
	if (options.pipeOutput) {
		ffmpeg.stdout.pipe(process.stdout);
		ffmpeg.stderr.pipe(process.stderr);
	}

	console.log('ffmpeg0');
	const closed = new Promise((resolve, reject) => {
		ffmpeg.on('error', reject);
		ffmpeg.on('close', resolve);
	});

	console.log('ffmpeg1');
	const browser = await puppeteer.launch({
		headless: true,
		// devtools: true,
		defaultViewport: {
			width: viewportWidth,
			height: viewportHeight,
			deviceScaleFactor: parseFloat(process.argv[5]),
		},
	});

	const page = await browser.newPage();
	await page.goto('http://localhost:1234/');

	await page.evaluate(async () => {
		await new Promise(function (resolve) {
			setTimeout(resolve, 1000);
		});
	});

	await page.evaluate(async () => {
		window.simApp.initVideo();
	});

	for (let ii = 0; ii < 30 * 20; ii++) {
		await page.evaluate(async () => {
			window.simApp.updateVideo(1 / 30);
			await window.simApp.loop();
		});
		let screenshot = await page.screenshot({
			fullPage: false,
		});
		await write(ffmpeg.stdin, screenshot);
	}

	console.log('done!');
	ffmpeg.stdin.end();
	await closed;
	await browser.close();
})();

package.json

{
	"name": "packet-data-node",
	"version": "1.0.0",
	"main": "index.js",
	"license": "MIT",
	"dependencies": {
		"child_process": "^1.0.2",
		"fluent-ffmpeg": "^2.1.2",
		"puppeteer": "^5.2.0"
	},
	"scripts": {
		"start": "node capture.js"
	}
}