canvasStream.js

import ffmpeg from 'fluent-ffmpeg';
import Canvas from 'canvas';
import path from 'path';
import debug from 'debug';
import { Readable } from 'stream';
import fs from 'fs';

const HWM = 90000;
const debugFFMPEG = debug('VoteLive:FFMPEG');
const debugCanvas = debug('VoteLive:Canvas');

let index = 0;

class CanvasStream extends Readable {
  constructor(options) {
    super({
      ...options,
    });

    this.canvas = new Canvas(1280, 720);
    this.ctx = this.canvas.getContext('2d');
    this.start = Date.now();
  }

  draw() {
    this.ctx.fillStyle = '#08c';
    this.ctx.fillRect(20, 20, 1240, 680);

    this.ctx.font = '72px sans-serif';
    this.ctx.fillStyle = '#4a4a4a';
    this.ctx.fillText(`Started ${Date.now() - this.start} ms`, 500, 240);
  }

  _read() {
    this.draw();
    this.imgBuf = this.canvas.toBuffer();

    index += 1;

    console.log(`Frame: ${index}\tBuffer Len: ${this._readableState.length}\tImage Len: ${this.imgBuf.length}`);

    if (index > 200) {
      this.push(null);
    } else {
      this.push(this.imgBuf);
    }
  }
}

const canvasStream = new CanvasStream();

ffmpeg(canvasStream)
  .inputOptions('-r 20')
  .inputOptions('-video_size 1280x720')
  .inputOptions('-pix_fmt yuv420p')
  .on('start', (command) => {
    debugFFMPEG(`Spawn ffmpeg: ${command}`);
  })
  .on('codecData', (data) => {
    debugFFMPEG('Input is ' + data.audio + ' audio ' + 'with ' + data.video + ' video');
  })
  .on('progress', (progress) => {
    if (progress.percent) {
      debugFFMPEG('Processing: ' + progress.percent + '% done', progress);
    } else {
      debugFFMPEG(`Processing: ${progress.frames} frames done.\t${progress.timemark} (FPS: ${progress.currentFps})`);
    }
  })
  .on('error', (err, stdout, stderr) => {
    debugFFMPEG(`error: ${err.message}`);
    debugFFMPEG(`stdout: ${stdout}`);
    debugFFMPEG(`stderr: ${stderr}`);
  })
  .on('end', () => {
    debugFFMPEG('FFMPEG end.');
  })
  .addOptions([
    '-bufsize 50000',
    '-c:v libx264',
    '-crf 28',
    '-preset ultrafast',
    '-r 30',
  ])
  .format('flv')
  .save('./test.flv');