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API World Hackathon Report No.1 - How to record a web-camera video in React

takumon profile image Takumon ・2 min read

This is a report written by a frontend engineer who joined hackathon for the first time.
I will be explaining RecordRTC for recording web-camera video in React.

What is API World

"API world" is the event organized by API. Their event page is attached below;

the world's largest vendor-neutral API conference and expo - https://apiworld.co/

AIP world has a two-days hackathon with 100 people.

Hackathon result

Our team was formed by 3 frontend developers(including myself) and 3 backend developers.

We took on the challenge of a sponsor that provides a cloud communications infrastructure called RingCentral.

Our project was selected as 1st prize of the RingCentral challenge for an interesting communication application and was selected as the top 5 of all teams.

Our project

We developed a web application that tells you the users if they are interested in the commercial they are watching.

The demo page is below.

demo page

When users click a movie, a separate modal window will be shown and the movie will be played.
At the same time, the web-camera recording will start for capturing the facial expressions of users watching the movie,
Technology stacks we used are listed below:

I was in charge of the following frontend implementation.

  • Movie list page
  • Web-camera recording function

Please visit our product page in Devpost (the following URL) for the details.

How to record a web-camera video in React

I used a library called RecordRTC for web-camera recording in React.

Implementation of web-camera recordings is easy.

A simple example of web-camera recording function is shown below;

import React from 'react';
import RecordRTC from 'recordrtc';

class CameraRecorder extends React.Component {
  constructor(props) {
    this.state = { recordVideo: null };

    this.requestUserMedia = this.requestUserMedia.bind(this);
    this.startRecord = this.startRecord.bind(this);
    this.stopRecord = this.stopRecord.bind(this);
    this.getUserMedia = this.getUserMedia.bind(this);

  requestUserMedia() {
    this.getUserMedia(stream => {
      this.setState({ src: window.URL.createObjectURL(stream) });

  startRecord() {
    this.getUserMedia(stream => {
      this.state.recordVideo = RecordRTC(stream, { type: 'video' });

  stopRecord() {
    this.state.recordVideo.stopRecording(() => {

  getUserMedia(callback) {
    navigator.getUserMedia({ audio: false, video: true }, callback, error => alert(JSON.stringify(error)));

  render() {
    return (
        <button onClick={this.startRecord}>Start Record</button>
        <button onClick={this.stopRecord}>Stop Record</button>

export default CameraRecorder;

What I felt in the hackathon

It was the first hackathon in my life and I am extremely pleased to end up as a member of the top 5 winning teams. Being able to translate my teammates’ ideas into concrete code gave me a great sense of satisfaction and I look forward to participating in future hackathons to relive the same experience as the one I experienced here.

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takumon profile



Software engineer, JavaScript(React.js, Vue.js, Angular), Java, Twitter(https://twitter.com/inouetakumon), Weekly blog(https://takumon.com), Qiita(https://qiita.com/Takumon)

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