Live stream with WebRTC in your Laravel application
Tags: webrtc, livestreaming, laravel, vue
Published: 2021-03-23 08:32:33

# Introduction
My first attempt at WebRTC was to implement a video call feature within a Laravel Application. The implementation involved placing a call, showing an incoming call notification, and the ability of the receiver to accept the call. I wrote about it over here: {% link https://dev.to/mupati/adding-video-chat-to-your-laravel-app-5ak7 %}

One of my readers asked whether it was possible to build a live streaming application with WebRTC in a Laravel Application. I took up this challenge and even though WebRTC has limitations, I came up with a simple live streaming implementation.

We'll go through my implementation in this article.

Final Project Repository: <a href="https://github.com/Mupati/laravel-video-chat">https://github.com/Mupati/laravel-video-chat</a> Note that this repository contains code for some other technical articles.

# Requirements
* This tutorial assumes you know how to set up a new `Laravel` project with `VueJs` authentication. Create some users after setting up your project. You should be familiar with Laravel's broadcasting mechanism and have a fair idea of how WebSockets work. You may use this starter project I created: [Laravel 8 Vue Auth Starter](https://github.com/Mupati/laravel-8-vue-auth-starter)

* Set up a free pusher account on <a href="https://pusher.com">pusher.com</a>

* Set up your ICE SERVER (TURN SERVER) details. This tutorial is a good guide. <a href="https://meetrix.io/blog/webrtc/coturn/installation.html">HOW TO INSTALL COTURN</a>. 

# Project Setup
```bash
# Install needed packages
composer require pusher/pusher-PHP-server "~4.0"
npm install --save laravel-echo pusher-js simple-peer
```


## Configuring Backend

* Add routes for streaming pages in `routes/web.php`.
The routes will be used to visit the live stream page, start a live stream from the device camera, and generate a broadcast link for other authenticated users to view your live stream.
```php
    Route::get('/streaming', 'App\Http\Controllers\WebrtcStreamingController@index');
    Route::get('/streaming/{streamId}', 'App\Http\Controllers\WebrtcStreamingController@consumer');
    Route::post('/stream-offer', 'App\Http\Controllers\WebrtcStreamingController@makeStreamOffer');
    Route::post('/stream-answer', 'App\Http\Controllers\WebrtcStreamingController@makeStreamAnswer');
``` 


* Uncomment `BroadcastServiceProvider` in `config/app.php`. This allows us to use Laravel's broadcasting system.
```diff
+ App\Providers\BroadcastServiceProvider::class
- //App\Providers\BroadcastServiceProvider::class 
```


* Create Dynamic Presence and Private Channel in routes/channels.php. 

Authenticated users subscribe to both channels. 
The presence channel is dynamically created with a `streamId` generated by the broadcaster. This way, we can detect all users who have joined the live broadcast.

Signaling information is exchanged between the broadcaster and the viewer through the private channel.
```php
// Dynamic Presence Channel for Streaming
Broadcast::channel('streaming-channel.{streamId}', function ($user) {
    return ['id' => $user->id, 'name' => $user->name];
});

// Signaling Offer and Answer Channels
Broadcast::channel('stream-signal-channel.{userId}', function ($user, $userId) {
    return (int) $user->id === (int) $userId;
});

```


* Create `StreamOffer` and `StreamAnswer` events.
Signaling information is broadcast on the `stream-signal-channel-{userId}` private channel we created early on.

The broadcaster sends an offer to a new user who joins the live stream when we emit the `StreamOffer` event and the viewer replies with an answer using the `StreamAnswer` event.

```bash
php artisan make:event StreamOffer
php artisan make:event StreamAnswer
```


* Add the following code to `app/Events/StreamOffer.php`.

```php
<?php

namespace App\Events;

use Illuminate\Broadcasting\InteractsWithSockets;
use Illuminate\Broadcasting\PrivateChannel;
use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
use Illuminate\Foundation\Events\Dispatchable;
use Illuminate\Queue\SerializesModels;

class StreamOffer implements ShouldBroadcast
{
    use Dispatchable, InteractsWithSockets, SerializesModels;

    public $data;
    /**
     * Create a new event instance.
     *
     * @return void
     */
    public function __construct($data)
    {
        $this->data = $data;
    }

    /**
     * Get the channels the event should broadcast on.
     *
     * @return \Illuminate\Broadcasting\Channel|array
     */
    public function broadcastOn()
    {
        // stream offer can broadcast on a private channel
        return  new PrivateChannel('stream-signal-channel.' . $this->data['receiver']['id']);
    }
}
```


* Add the following code to `app/Events/StreamAnswer.php`.
```php
<?php

namespace App\Events;

use Illuminate\Broadcasting\InteractsWithSockets;
use Illuminate\Broadcasting\PrivateChannel;
use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
use Illuminate\Foundation\Events\Dispatchable;
use Illuminate\Queue\SerializesModels;

class StreamAnswer implements ShouldBroadcast
{
    use Dispatchable, InteractsWithSockets, SerializesModels;

    public $data;
    /**
     * Create a new event instance.
     *
     * @return void
     */
    public function __construct($data)
    {
        $this->data = $data;
    }

    /**
     * Get the channels the event should broadcast on.
     *
     * @return \Illuminate\Broadcasting\Channel|array
     */
    public function broadcastOn()
    {
        return  new PrivateChannel('stream-signal-channel.' . $this->data['broadcaster']);
    }
}

```


* Create `WebrtcStreamingController` to handle the broadcasting, viewing, and signaling for the live stream.
```bash
php artisan make:controller WebrtcStreamingController
```
* Add the following to the `WebrtcStreamingController`
```php
<?php

namespace App\Http\Controllers;

use App\Events\StreamAnswer;
use App\Events\StreamOffer;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;

class WebrtcStreamingController extends Controller
{

    public function index()
    {
        return view('video-broadcast', ['type' => 'broadcaster', 'id' => Auth::id()]);
    }

    public function consumer(Request $request, $streamId)
    {
        return view('video-broadcast', ['type' => 'consumer', 'streamId' => $streamId, 'id' => Auth::id()]);
    }

    public function makeStreamOffer(Request $request)
    {
        $data['broadcaster'] = $request->broadcaster;
        $data['receiver'] = $request->receiver;
        $data['offer'] = $request->offer;

        event(new StreamOffer($data));
    }

    public function makeStreamAnswer(Request $request)
    {
        $data['broadcaster'] = $request->broadcaster;
        $data['answer'] = $request->answer;
        event(new StreamAnswer($data));
    }
}

```


### Methods in the WebrtcStreamingController
Let's explore what the methods in the controller are doing.

* `index`: This returns the view for the broadcaster. We pass a 'type': broadcaster and the user's ID into the view to help identify who the user is.
* `consumer`: It returns the view for a new user who wants to join the live stream. We pass a 'type': consumer, the 'streamId' we extract from the broadcasting link, and the user's ID.
* `makeStreamOffer`: It broadcasts an offer signal sent by the broadcaster to a specific user who just joined. The following data is sent:
    * `broadcaster`: The user ID of the one who initiated the live stream i.e the broadcaster
    * `receiver`: The ID of the user to whom the signaling offer is being sent.
    * `offer`: This is the WebRTC offer from the broadcaster.

* `makeStreamAnswer`: It sends an answer signal to the broadcaster to fully establish the peer connection.
    * `broadcaster`: The user ID of the one who initiated the live stream i.e the broadcaster.
    * `answer`: This is the WebRTC answer from the viewer after, sent after receiving an offer from the broadcaster.


## Configuring Frontend
* Instantiate `Laravel Echo` and `Pusher` in `resources/js/bootstrap.js` by uncommenting the following block of code.

```diff
+ import Echo from 'laravel-echo';
+ window.Pusher = require('pusher-js');
+ window.Echo = new Echo({
+     broadcaster: 'pusher',
+     key: process.env.MIX_PUSHER_APP_KEY,
+     cluster: process.env.MIX_PUSHER_APP_CLUSTER,
+     forceTLS: true
+ });
- import Echo from 'laravel-echo';
- window.Pusher = require('pusher-js');
- window.Echo = new Echo({
-     broadcaster: 'pusher',
-     key: process.env.MIX_PUSHER_APP_KEY,
-     cluster: process.env.MIX_PUSHER_APP_CLUSTER,
-     forceTLS: true
-});
```


* Create `resources/js/helpers.js`.
Add a `getPermissions` function to help with permission access for the microphone and camera. This method handles the video and audio permission that is required by browsers to make the video calls. It waits for the user to accept the permissions before we can proceed with the video call. We allow both audio and video.
Read more on <a href="https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia" target="_blank">MDN Website</a>.
```js
export const getPermissions = () => {
    // Older browsers might not implement mediaDevices at all, so we set an empty object first
    if (navigator.mediaDevices === undefined) {
        navigator.mediaDevices = {};
    }

    // Some browsers partially implement media devices. We can't just assign an object
    // with getUserMedia as it would overwrite existing properties.
    // Here, we will just add the getUserMedia property if it's missing.
    if (navigator.mediaDevices.getUserMedia === undefined) {
        navigator.mediaDevices.getUserMedia = function(constraints) {
            // First get ahold of the legacy getUserMedia, if present
            const getUserMedia =
                navigator.webkitGetUserMedia || navigator.mozGetUserMedia;

            // Some browsers just don't implement it - return a rejected promise with an error
            // to keep a consistent interface
            if (!getUserMedia) {
                return Promise.reject(
                    new Error("getUserMedia is not implemented in this browser")
                );
            }

            // Otherwise, wrap the call to the old navigator.getUserMedia with a Promise
            return new Promise((resolve, reject) => {
                getUserMedia.call(navigator, constraints, resolve, reject);
            });
        };
    }
    navigator.mediaDevices.getUserMedia =
        navigator.mediaDevices.getUserMedia ||
        navigator.webkitGetUserMedia ||
        navigator.mozGetUserMedia;

    return new Promise((resolve, reject) => {
        navigator.mediaDevices
            .getUserMedia({ video: true, audio: true })
            .then(stream => {
                resolve(stream);
            })
            .catch(err => {
                reject(err);
                //   throw new Error(`Unable to fetch stream ${err}`);
            });
    });
};
```


* Create a component for the Broadcaster named Broadcaster.vue in `resources/js/components/Broadcaster.vue`.
{% gist https://gist.github.com/Mupati/c524f3896f92c93d5609bcf67ec75060 %}


* Create a component for the Viewer named Viewer.vue in `resources/js/components/Viewer.vue`.
{% gist https://gist.github.com/Mupati/048efa9eaae9165a49258296b291e56d %}


#### Explanation of the Broadcaster and Viewer components.
The following video explains the call logic on the client-side from the perspective of both Broadcaster and Viewers.
{% youtube qcT-QSSQEuU %}


* Register the `Broadcaster.vue` and `Viewer.vue` components in `resources/js/app.js`


```bash
//  Streaming Components
Vue.component("broadcaster", require("./components/Broadcaster.vue").default);
Vue.component("viewer", require("./components/Viewer.vue").default);
```


* Create the video broadcast view in `resources/views/video-broadcast.blade.php`
{% gist https://gist.github.com/Mupati/c2d2bef7976fc955525503b3c5611f13 %}


* Update env variables. Insert your Pusher API keys

```env
APP_ENV=

BROADCAST_DRIVER=pusher

PUSHER_APP_ID=
PUSHER_APP_KEY=
PUSHER_APP_SECRET=
PUSHER_APP_CLUSTER=

TURN_SERVER_URL=
TURN_SERVER_USERNAME=
TURN_SERVER_CREDENTIAL=
```


## Live Stream Demo
{% youtube 29X-lcFGFVU %}



## Final Thoughts
The logic for this live streaming application can be likened to a group video call where only one person's stream is seen. 

The stream of the broadcaster is rendered on the viewers' browser but the broadcaster doesn't receive anything from the viewers after exchanging the signaling information which is required in WebRTC.

This looks like a star topology and there is a limitation on how many peers can be connected to a single user.

I want to explore the option of turning some of the viewers into broadcasters after the initial broadcaster's peer has connected to about 4 users.

The goal is to rebroadcast the stream they received from the original broadcaster.

Is it possible? I can't tell. This will be an interesting challenge to explore. 

Stay tuned!!!.