Build a Video Chat App with ASP.NET Core 2.2, Angular, and Twilio

setx TWILIO_ACCOUNT_SID [Account SID]
setx TWILIO_API_SECRET [API Secret]
setx TWILIO_API_KEY [SID]

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning"
    }
  },
  "AllowedHosts": "*",
  "TwilioSettings": {
    "AccountSid": "Account SID",
    "ApiSecret": "API Secret",
    "ApiKey": "SID"
    }
}

dotnet new angular -o VideoChat

dotnet add package Twilio

<ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.AspNetCore.SpaServices.Extensions" Version="2.2.0" />
    <PackageReference Include="Twilio" Version="5.25.1" />
</ItemGroup>

namespace VideoChat.Options
{
    public class TwilioSettings
    {
        /// <summary>
        /// The primary Twilio account SID, displayed prominently on your twilio.com/console dashboard.
        /// </summary>
        public string AccountSid { get; set; }
        
        /// <summary>
        /// The auth token for your primary Twilio account, hidden on your twilio.com/console dashboard.
        /// </summary>
        public string AuthToken { get; set; }

        /// <summary>
        /// Signing Key SID, also known as the API SID or API Key.
        /// </summary>
        public string ApiKey { get; set; }

        /// <summary>
        /// The API Secret that corresponds to the <see cref="ApiKey"/>.
        /// </summary>
        public string ApiSecret { get; set; }
    }
}

namespace VideoChat.Models
{
    public class RoomDetails
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public int ParticipantCount { get; set; }
        public int MaxParticipants { get; set; }
    }
}

using System.Collections.Generic;
using System.Threading.Tasks;
using VideoChat.Models;

namespace VideoChat.Abstractions
{
    public interface IVideoService
    {
        string GetTwilioJwt(string identity);
        Task<IEnumerable<RoomDetails>> GetAllRoomsAsync();
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using VideoChat.Abstractions;
using VideoChat.Models;
using VideoChat.Options;
using Twilio;
using Twilio.Base;
using Twilio.Jwt.AccessToken;
using Twilio.Rest.Video.V1;
using Twilio.Rest.Video.V1.Room;
using ParticipantStatus = Twilio.Rest.Video.V1.Room.ParticipantResource.StatusEnum;

namespace VideoChat.Services
{
    public class VideoService : IVideoService
    {
        readonly TwilioSettings _twilioSettings;

        public VideoService(Microsoft.Extensions.Options.IOptions<TwilioSettings> twilioOptions)
        {
            _twilioSettings =
                twilioOptions?.Value
             ?? throw new ArgumentNullException(nameof(twilioOptions));

            TwilioClient.Init(_twilioSettings.ApiKey, _twilioSettings.ApiSecret);
        }

        public string GetTwilioJwt(string identity)
            => new Token(_twilioSettings.AccountSid,
                         _twilioSettings.ApiKey,
                         _twilioSettings.ApiSecret,
                         identity ?? Guid.NewGuid().ToString(),
                         grants: new HashSet<IGrant> { new VideoGrant() }).ToJwt();

        public async Task<IEnumerable<RoomDetails>> GetAllRoomsAsync()
        {
            var rooms = await RoomResource.ReadAsync();
            var tasks = rooms.Select(
                room => GetRoomDetailsAsync(
                    room,
                    ParticipantResource.ReadAsync(
                        room.Sid,
                        ParticipantStatus.Connected)));

            return await Task.WhenAll(tasks);

            async Task<RoomDetails> GetRoomDetailsAsync(
                RoomResource room,
                Task<ResourceSet<ParticipantResource>> participantTask)
            {
                var participants = await participantTask;
                return new RoomDetails
                {
                    Name = room.UniqueName,
                    MaxParticipants = room.MaxParticipants ?? 0,
                    ParticipantCount = participants.ToList().Count
                };
            }
        }
    }
}

using System.Threading.Tasks;
using VideoChat.Abstractions;
using Microsoft.AspNetCore.Mvc;

namespace VideoChat.Controllers
{
    [
        ApiController,
        Route("api/video")
    ]
    public class VideoController : ControllerBase
    {
        readonly IVideoService _videoService;

        public VideoController(IVideoService videoService)
            => _videoService = videoService;

        [HttpGet("token")]
        public IActionResult GetToken()
            => new JsonResult(new { token = _videoService.GetTwilioJwt(User.Identity.Name) });

        [HttpGet("rooms")]
        public async Task<IActionResult> GetRooms()
            => new JsonResult(await _videoService.GetAllRoomsAsync());
    }
}

using System.Threading.Tasks;
using Microsoft.AspNetCore.SignalR;

namespace VideoChat.Hubs
{
    public class NotificationHub : Hub
    {
        public async Task RoomsUpdated(bool flag)
            => await Clients.Others.SendAsync("RoomsUpdated", flag);
    }
}

using VideoChat.Abstractions;
using VideoChat.Hubs;
using VideoChat.Options;
using VideoChat.Services;

services.Configure<TwilioSettings>(Configuration.GetSection(nameof(TwilioSettings)))
        .AddTransient<IVideoService, VideoService>()
        .AddSpaStaticFiles(configuration => configuration.RootPath = "ClientApp/dist/ClientApp");

services.AddSignalR();

app.UseSignalR(routes =>
   {
       routes.MapHub<NotificationHub>("/notificationHub");
   });

ng n ClientApp --style css --routing false --minimal true --skipTests true

{
  "name": "video-chat",
  "version": "0.0.1",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "lint": "ng lint"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "~7.1.4",
    "@angular/common": "~7.1.4",
    "@angular/compiler": "~7.1.4",
    "@angular/core": "~7.1.4",
    "@angular/forms": "~7.1.4",
    "@angular/platform-browser": "~7.1.4",
    "@angular/platform-browser-dynamic": "~7.1.4",
    "@angular/router": "~7.1.4",
    "@aspnet/signalr": "1.1.0",
    "twilio-video": "2.0.0-beta5",
    "core-js": "^2.5.4",
    "rxjs": "~6.3.3",
    "tslib": "^1.9.0",
    "zone.js": "~0.8.26"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.11.0",
    "@angular/cli": "~7.1.4",
    "@angular/compiler-cli": "~7.1.4",
    "@angular/language-service": "~7.1.4",
    "@types/node": "~8.9.4",
    "codelyzer": "~4.5.0",
    "ts-node": "~7.0.0",
    "tslint": "~5.11.0",
    "typescript": "~3.1.6"
  }
}

npm install

<link rel="stylesheet"
      href="https://use.fontawesome.com/releases/v5.6.3/css/all.css"
     integrity="sha384-UHRtZLI+pbxtHCWp1t77Bi1L4ZtiqrqD80Kn4Z8NTSRyMA2Fd33n5dQ8lWUE00s/"
      crossorigin="anonymous">
<link rel="stylesheet"
      href="https://bootswatch.com/4/darkly/bootstrap.min.css">

<app-home></app-home>

ng g c camera --nospec
ng g c home --nospec
ng g c participants --nospec
ng g c rooms --nospec
ng g c settings --nospec
ng g c settings/device-select --nospec --flat true

ng g s services/videochat --nospec
ng g s services/device --nospec

import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';

imports: [
  BrowserModule,
  HttpClientModule,
  FormsModule
],

// https://github.com/angular/angular-cli/issues/9827#issuecomment-386154063
// Add global to window, assigning the value of window itself.
(window as any).global = window;

import { Injectable } from '@angular/core';
import { ReplaySubject, Observable } from 'rxjs';

export type Devices = MediaDeviceInfo[];

@Injectable({
    providedIn: 'root'
})
export class DeviceService {
    $devicesUpdated: Observable<Promise<Devices>>;

    private deviceBroadcast = new ReplaySubject<Promise<Devices>>();

    constructor() {
        if (navigator && navigator.mediaDevices) {
            navigator.mediaDevices.ondevicechange = (_: Event) => {
                this.deviceBroadcast.next(this.getDeviceOptions());
            }
        }

        this.$devicesUpdated = this.deviceBroadcast.asObservable();
        this.deviceBroadcast.next(this.getDeviceOptions());
    }

    private async isGrantedMediaPermissions() {
        if (navigator && navigator['permissions']) {
            try {
                const result = await navigator['permissions'].query({ name: 'camera' });
                if (result) {
                    if (result.state === 'granted') {
                        return true;
                    } else {
                        const isGranted = await new Promise<boolean>(resolve => {
                            result.onchange = (_: Event) => {
                                const granted = _.target['state'] === 'granted';
                                if (granted) {
                                    resolve(true);
                                }
                            }
                        });

                        return isGranted;
                    }
                }
            } catch (e) {
                // This is only currently supported in Chrome.
                // https://stackoverflow.com/a/53155894/2410379
                return true;
            }
        }

        return false;
    }

    private async getDeviceOptions(): Promise<Devices> {
        const isGranted = await this.isGrantedMediaPermissions();
        if (navigator && navigator.mediaDevices && isGranted) {
            let devices = await this.tryGetDevices();
            if (devices.every(d => !d.label)) {
                devices = await this.tryGetDevices();
            }
            return devices;
        }

        return null;
    }

    private async tryGetDevices() {
        const mediaDevices = await navigator.mediaDevices.enumerateDevices();
        const devices = ['audioinput', 'audiooutput', 'videoinput'].reduce((options, kind) => {
            return options[kind] = mediaDevices.filter(device => device.kind === kind);
        }, [] as Devices);

        return devices;
    }
}

import { connect, ConnectOptions, LocalTrack, Room } from 'twilio-video';
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { ReplaySubject , Observable } from 'rxjs';

interface AuthToken {
    token: string;
}

export interface NamedRoom {
    id: string;
    name: string;
    maxParticipants?: number;
    participantCount: number;
}

export type Rooms = NamedRoom[];

@Injectable({
    providedIn: 'root'
})
export class VideoChatService {
    $roomsUpdated: Observable<boolean>;

    private roomBroadcast = new ReplaySubject<boolean>();

    constructor(private readonly http: HttpClient) {
        this.$roomsUpdated = this.roomBroadcast.asObservable();
    }

    private async getAuthToken() {
        const auth =
            await this.http
                      .get<AuthToken>(`api/video/token`)
                      .toPromise();

        return auth.token;
    }

    getAllRooms() {
        return this.http
                   .get<Rooms>('api/video/rooms')
                   .toPromise();
    }

    async joinOrCreateRoom(name: string, tracks: LocalTrack[]) {
        let room: Room = null;
        try {
            const token = await this.getAuthToken();
            room =
                await connect(
                    token, {
                        name,
                        tracks,
                        dominantSpeaker: true
                    } as ConnectOptions);
        } catch (error) {
            console.error(`Unable to connect to Room: ${error.message}`);
        } finally {
            if (room) {
                this.roomBroadcast.next(true);
            }
        }

        return room;
    }

    nudge() {
        this.roomBroadcast.next(true);
    }
}

import { Component, ElementRef, ViewChild, AfterViewInit, Renderer2 } from '@angular/core';
import { createLocalTracks, LocalTrack, LocalVideoTrack } from 'twilio-video';

@Component({
    selector: 'app-camera',
    styleUrls: ['./camera.component.css'],
    templateUrl: './camera.component.html',
})
export class CameraComponent implements AfterViewInit {
    @ViewChild('preview') previewElement: ElementRef;

    get tracks(): LocalTrack[] {
        return this.localTracks;
    }

    isInitializing: boolean = true;

    private videoTrack: LocalVideoTrack;
    private localTracks: LocalTrack[] = [];

    constructor(
        private readonly renderer: Renderer2) { }

    async ngAfterViewInit() {
        if (this.previewElement && this.previewElement.nativeElement) {
            await this.initializeDevice();
        }
    }

    initializePreview(deviceInfo?: MediaDeviceInfo) {
        if (deviceInfo) {
            this.initializeDevice(deviceInfo.kind, deviceInfo.deviceId);
        } else {
            this.initializeDevice();
        }
    }

    finalizePreview() {
        try {
            if (this.videoTrack) {
                this.videoTrack.detach().forEach(element => element.remove());
            }
        } catch (e) {
            console.error(e);
        }
    }

    private async initializeDevice(kind?: MediaDeviceKind, deviceId?: string) {
        try {
            this.isInitializing = true;

            this.finalizePreview();

            this.localTracks = kind && deviceId
                ? await this.initializeTracks(kind, deviceId)
                : await this.initializeTracks();

            this.videoTrack = this.localTracks.find(t => t.kind === 'video') as LocalVideoTrack;
            const videoElement = this.videoTrack.attach();
            this.renderer.setStyle(videoElement, 'height', '100%');
            this.renderer.setStyle(videoElement, 'width', '100%');
            this.renderer.appendChild(this.previewElement.nativeElement, videoElement);
        } finally {
            this.isInitializing = false;
        }
    }

    private initializeTracks(kind?: MediaDeviceKind, deviceId?: string) {
        if (kind) {
            switch (kind) {
                case 'audioinput':
                    return createLocalTracks({ audio: { deviceId }, video: true });
                case 'videoinput':
                    return createLocalTracks({ audio: true, video: { deviceId } });
            }
        }

        return createLocalTracks({ audio: true, video: true });
    }
}

<div id="preview" #preview>
    <div *ngIf="isInitializing">Loading preview... Please wait.</div>
</div>

<div class="jumbotron">
    <h5 class="display-4"><i class="fas fa-video"></i> Rooms</h5>
    <div class="list-group">
        <div class="list-group-item d-flex justify-content-between align-items-center">
            <div class="input-group">
                <input type="text" class="form-control form-control-lg"
                       placeholder="Room Name" aria-label="Room Name"
                       [(ngModel)]="roomName" (keydown.enter)="onTryAddRoom()">
                <div class="input-group-append">
                    <button class="btn btn-lg btn-outline-secondary twitter-red"
                            type="button" [disabled]="!roomName"
                            (click)="onAddRoom(roomName)">
                        <i class="far fa-plus-square"></i> Create
                    </button>
                </div>
            </div>
        </div>
        <div *ngIf="!rooms || !rooms.length" class="list-group-item d-flex justify-content-between align-items-center">
            <p class="lead">
                Add a room to begin. Other online participants can join or create rooms.
            </p>
        </div>
        <a href="#" *ngFor="let room of rooms"
           (click)="onJoinRoom(room.name)" [ngClass]="{ 'active': activeRoomName === room.name }"
           class="list-group-item list-group-item-action d-flex justify-content-between align-items-center">
            {{ room.name }}
            <span class="badge badge-primary badge-pill">
                {{ room.participantCount }} / {{ room.maxParticipants }}
            </span>
        </a>
    </div>
</div>

import { Component, OnInit, OnDestroy, EventEmitter, Output, Input } from '@angular/core';
import { Subscription } from 'rxjs';
import { tap } from 'rxjs/operators';
import { NamedRoom, VideoChatService } from '../services/videochat.service';

@Component({
    selector: 'app-rooms',
    styleUrls: ['./rooms.component.css'],
    templateUrl: './rooms.component.html',
})
export class RoomsComponent implements OnInit, OnDestroy {
    @Output() roomChanged = new EventEmitter<string>();
    @Input() activeRoomName: string;

    roomName: string;
    rooms: NamedRoom[];

    private subscription: Subscription;

    constructor(
        private readonly videoChatService: VideoChatService) { }

    async ngOnInit() {
        await this.updateRooms();
        this.subscription =
            this.videoChatService
                .$roomsUpdated
                .pipe(tap(_ => this.updateRooms()))
                .subscribe();
    }

    ngOnDestroy() {
        if (this.subscription) {
            this.subscription.unsubscribe();
        }
    }

    onTryAddRoom() {
        if (this.roomName) {
            this.onAddRoom(this.roomName);
        }
    }

    onAddRoom(roomName: string) {
        this.roomName = null;
        this.roomChanged.emit(roomName);
    }

    onJoinRoom(roomName: string) {
        this.roomChanged.emit(roomName);
    }

    async updateRooms() {
        this.rooms = (await this.videoChatService.getAllRooms()) as NamedRoom[];
    }
}

import {
    Component,
    ViewChild,
    ElementRef,
    Output,
    Input,
    EventEmitter,
    Renderer2
} from '@angular/core';
import {
    Participant,
    RemoteTrack,
    RemoteAudioTrack,
    RemoteVideoTrack,
    RemoteParticipant,
    RemoteTrackPublication
} from 'twilio-video';

@Component({
    selector: 'app-participants',
    styleUrls: ['./participants.component.css'],
    templateUrl: './participants.component.html',
})
export class ParticipantsComponent {
    @ViewChild('list') listRef: ElementRef;
    @Output('participantsChanged') participantsChanged = new EventEmitter<boolean>();
    @Output('leaveRoom') leaveRoom = new EventEmitter<boolean>();
    @Input('activeRoomName') activeRoomName: string;

    get participantCount() {
        return !!this.participants ? this.participants.size : 0;
    }

    get isAlone() {
        return this.participantCount === 0;
    }

    private participants: Map<Participant.SID, RemoteParticipant>;
    private dominantSpeaker: RemoteParticipant;

    constructor(private readonly renderer: Renderer2) { }

    clear() {
        if (this.participants) {
            this.participants.clear();
        }
    }

    initialize(participants: Map<Participant.SID, RemoteParticipant>) {
        this.participants = participants;
        if (this.participants) {
            this.participants.forEach(participant => this.registerParticipantEvents(participant));
        }
    }

    add(participant: RemoteParticipant) {
        if (this.participants && participant) {
            this.participants.set(participant.sid, participant);
            this.registerParticipantEvents(participant);
        }
    }

    remove(participant: RemoteParticipant) {
        if (this.participants && this.participants.has(participant.sid)) {
            this.participants.delete(participant.sid);
        }
    }

    loudest(participant: RemoteParticipant) {
        this.dominantSpeaker = participant;
    }

    onLeaveRoom() {
        this.leaveRoom.emit(true);
    }

    private registerParticipantEvents(participant: RemoteParticipant) {
        if (participant) {
            participant.tracks.forEach(publication => this.subscribe(publication));
            participant.on('trackPublished', publication => this.subscribe(publication));
            participant.on('trackUnpublished',
                publication => {
                    if (publication && publication.track) {
                        this.detachRemoteTrack(publication.track);
                    }
                });
        }
    }

    private subscribe(publication: RemoteTrackPublication | any) {
        if (publication && publication.on) {
            publication.on('subscribed', track => this.attachRemoteTrack(track));
            publication.on('unsubscribed', track => this.detachRemoteTrack(track));
        }
    }

    private attachRemoteTrack(track: RemoteTrack) {
        if (this.isAttachable(track)) {
            const element = track.attach();
            this.renderer.data.id = track.sid;
            this.renderer.setStyle(element, 'width', '95%');
            this.renderer.setStyle(element, 'margin-left', '2.5%');
            this.renderer.appendChild(this.listRef.nativeElement, element);
            this.participantsChanged.emit(true);
        }
    }

    private detachRemoteTrack(track: RemoteTrack) {
        if (this.isDetachable(track)) {
            track.detach().forEach(el => el.remove());
            this.participantsChanged.emit(true);
        }
    }

    private isAttachable(track: RemoteTrack): track is RemoteAudioTrack | RemoteVideoTrack {
        return !!track &&
            ((track as RemoteAudioTrack).attach !== undefined ||
            (track as RemoteVideoTrack).attach !== undefined);
    }

    private isDetachable(track: RemoteTrack): track is RemoteAudioTrack | RemoteVideoTrack {
        return !!track &&
            ((track as RemoteAudioTrack).detach !== undefined ||
            (track as RemoteVideoTrack).detach !== undefined);
    }
}

<div id="participant-list">
    <div id="alone" [ngClass]="{ 'table': isAlone, 'd-none': !isAlone }">
        <p class="text-center text-monospace h3" style="display: table-cell">
            You're the only one in this room. <i class="far fa-frown"></i>
            <br />
            <br />
            As others join, they'll start showing up here...
        </p>
    </div>
    <div [ngClass]="{ 'd-none': isAlone }">
        <nav class="navbar navbar-expand-lg navbar-dark bg-light shadow">
            <ul class="navbar-nav ml-auto">
                <li class="nav-item">
                    <button type="button" class="btn btn-lg leave-room"
                            title="Click to leave this room." (click)="onLeaveRoom()">
                        Leave "{{ activeRoomName }}" Room?
                    </button>
                </li>
            </ul>
        </nav>
        <div #list></div>
    </div>
</div>

import {
    Component,
    OnInit,
    OnDestroy,
    EventEmitter,
    Input,
    Output,
    ViewChild
} from '@angular/core';
import { CameraComponent } from '../camera/camera.component';
import { DeviceSelectComponent } from './device-select.component';
import { DeviceService } from '../services/device.service';
import { debounceTime } from 'rxjs/operators';
import { Subscription } from 'rxjs';

@Component({
    selector: 'app-settings',
    styleUrls: ['./settings.component.css'],
    templateUrl: './settings.component.html'
})
export class SettingsComponent implements OnInit, OnDestroy {
    private devices: MediaDeviceInfo[] = [];
    private subscription: Subscription;
    private videoDeviceId: string;

    get hasAudioInputOptions(): boolean {
        return this.devices && this.devices.filter(d => d.kind === 'audioinput').length > 0;
    }
    get hasAudioOutputOptions(): boolean {
        return this.devices && this.devices.filter(d => d.kind === 'audiooutput').length > 0;
    }
    get hasVideoInputOptions(): boolean {
        return this.devices && this.devices.filter(d => d.kind === 'videoinput').length > 0;
    }

    @ViewChild('camera') camera: CameraComponent;
    @ViewChild('videoSelect') video: DeviceSelectComponent;

    @Input('isPreviewing') isPreviewing: boolean;
    @Output() settingsChanged = new EventEmitter<MediaDeviceInfo>();

    constructor(
        private readonly deviceService: DeviceService) { }

    ngOnInit() {
        this.subscription =
            this.deviceService
                .$devicesUpdated
                .pipe(debounceTime(350))
                .subscribe(async deviceListPromise => {
                    this.devices = await deviceListPromise;
                    this.handleDeviceAvailabilityChanges();
                });
    }

    ngOnDestroy() {
        if (this.subscription) {
            this.subscription.unsubscribe();
        }
    }

    async onSettingsChanged(deviceInfo: MediaDeviceInfo) {
        if (this.isPreviewing) {
            await this.showPreviewCamera();
        } else {
            this.settingsChanged.emit(deviceInfo);
        }
    }

    async showPreviewCamera() {
        this.isPreviewing = true;

        if (this.videoDeviceId !== this.video.selectedId) {
            this.videoDeviceId = this.video.selectedId;
            const videoDevice = this.devices.find(d => d.deviceId === this.video.selectedId);
            await this.camera.initializePreview(videoDevice);
        }
        
        return this.camera.tracks;
    }

    hidePreviewCamera() {
        this.isPreviewing = false;
        this.camera.finalizePreview();
        return this.devices.find(d => d.deviceId === this.video.selectedId);
    }

    private handleDeviceAvailabilityChanges() {
        if (this.devices && this.devices.length && this.video && this.video.selectedId) {
            let videoDevice = this.devices.find(d => d.deviceId === this.video.selectedId);
            if (!videoDevice) {
                videoDevice = this.devices.find(d => d.kind === 'videoinput');
                if (videoDevice) {
                    this.video.selectedId = videoDevice.deviceId;
                    this.onSettingsChanged(videoDevice);
                }
            }
        }
    }
}

<div class="jumbotron">
    <h4 class="display-4"><i class="fas fa-cogs"></i> Settings</h4>
    <form class="form">
        <div class="form-group" *ngIf="hasAudioInputOptions">
            <app-device-select [kind]="'audioinput'"
                               [label]="'Audio Input Source'" [devices]="devices"
                               (settingsChanged)="onSettingsChanged($event)"></app-device-select>
        </div>
        <div class="form-group" *ngIf="hasAudioOutputOptions">
            <app-device-select [kind]="'audiooutput'"
                               [label]="'Audio Output Source'" [devices]="devices"
                               (settingsChanged)="onSettingsChanged($event)"></app-device-select>
        </div>
        <div class="form-group" *ngIf="hasVideoInputOptions">
            <app-device-select [kind]="'videoinput'" #videoSelect
                               [label]="'Video Input Source'" [devices]="devices"
                               (settingsChanged)="onSettingsChanged($event)"></app-device-select>
        </div>
    </form>
    <div [style.display]="isPreviewing ? 'block' : 'none'">
        <app-camera #camera></app-camera>
    </div>
</div>

import { Component, EventEmitter, Input, Output } from '@angular/core';

class IdGenerator {
    protected static id: number = 0;
    static getNext() {
        return ++ IdGenerator.id;
    }
}

@Component({
    selector: 'app-device-select',
    templateUrl: './device-select.component.html'
})
export class DeviceSelectComponent {
    private localDevices: MediaDeviceInfo[] = [];

    id: string;
    selectedId: string;

    get devices(): MediaDeviceInfo[] {
        return this.localDevices;
    }

    @Input() label: string;
    @Input() kind: MediaDeviceKind;
    @Input() set devices(devices: MediaDeviceInfo[]) {
        this.selectedId = this.find(this.localDevices = devices);
    }

    @Output() settingsChanged = new EventEmitter<MediaDeviceInfo>();

    constructor() {
        this.id = `device-select-${IdGenerator.getNext()}`;
    }

    onSettingsChanged(deviceId: string) {
        this.setAndEmitSelections(this.selectedId = deviceId);
    }

    private find(devices: MediaDeviceInfo[]) {
        if (devices && devices.length > 0) {
            return devices[0].deviceId;
        }

        return null;
    }

    private setAndEmitSelections(deviceId: string) {
        this.settingsChanged.emit(this.devices.find(d => d.deviceId === deviceId));
    }
}

<label for="{{ id }}" class="h5">{{ label }}</label>
<select class="custom-select" id="{{ id }}"
        (change)="onSettingsChanged($event.target.value)">
    <option *ngFor="let device of devices"
            [value]="device.deviceId" [selected]="device.deviceId === selectedId">
        {{ device.label }}
    </option>
</select>

import { Component, ViewChild, OnInit } from '@angular/core';
import { Room, LocalTrack, LocalVideoTrack, LocalAudioTrack, RemoteParticipant } from 'twilio-video';
import { RoomsComponent } from '../rooms/rooms.component';
import { CameraComponent } from '../camera/camera.component';
import { SettingsComponent } from '../settings/settings.component';
import { ParticipantsComponent } from '../participants/participants.component';
import { VideoChatService } from '../services/videochat.service';
import { HubConnection, HubConnectionBuilder, LogLevel } from '@aspnet/signalr';

@Component({
    selector: 'app-home',
    styleUrls: ['./home.component.css'],
    templateUrl: './home.component.html',
})
export class HomeComponent implements OnInit {
    @ViewChild('rooms') rooms: RoomsComponent;
    @ViewChild('camera') camera: CameraComponent;
    @ViewChild('settings') settings: SettingsComponent;
    @ViewChild('participants') participants: ParticipantsComponent;

    activeRoom: Room;

    private notificationHub: HubConnection;

    constructor(
        private readonly videoChatService: VideoChatService) { }

    async ngOnInit() {
        const builder =
            new HubConnectionBuilder()
                .configureLogging(LogLevel.Information)
                .withUrl(`${location.origin}/notificationHub`);

        this.notificationHub = builder.build();
        this.notificationHub.on('RoomsUpdated', async updated => {
            if (updated) {
                await this.rooms.updateRooms();
            }
        });
        await this.notificationHub.start();
    }

    async onSettingsChanged(deviceInfo: MediaDeviceInfo) {
        await this.camera.initializePreview(deviceInfo);
    }

    async onLeaveRoom(_: boolean) {
        if (this.activeRoom) {
            this.activeRoom.disconnect();
            this.activeRoom = null;
        }

        this.camera.finalizePreview();
        const videoDevice = this.settings.hidePreviewCamera();
        this.camera.initializePreview(videoDevice);

        this.participants.clear();
    }

    async onRoomChanged(roomName: string) {
        if (roomName) {
            if (this.activeRoom) {
                this.activeRoom.disconnect();
            }

            this.camera.finalizePreview();
            const tracks = await this.settings.showPreviewCamera();

            this.activeRoom =
                await this.videoChatService
                          .joinOrCreateRoom(roomName, tracks);

            this.participants.initialize(this.activeRoom.participants);
            this.registerRoomEvents();

            this.notificationHub.send('RoomsUpdated', true);
        }
    }

    onParticipantsChanged(_: boolean) {
        this.videoChatService.nudge();
    }

    private registerRoomEvents() {
        this.activeRoom
            .on('disconnected',
                (room: Room) => room.localParticipant.tracks.forEach(publication => this.detachLocalTrack(publication.track)))
            .on('participantConnected',
                (participant: RemoteParticipant) => this.participants.add(participant))
            .on('participantDisconnected',
                (participant: RemoteParticipant) => this.participants.remove(participant))
            .on('dominantSpeakerChanged',
                (dominantSpeaker: RemoteParticipant) => this.participants.loudest(dominantSpeaker));
    }

    private detachLocalTrack(track: LocalTrack) {
        if (this.isDetachable(track)) {
            track.detach().forEach(el => el.remove());
        }
    }

    private isDetachable(track: LocalTrack): track is LocalAudioTrack | LocalVideoTrack {
        return !!track
            && ((track as LocalAudioTrack).detach !== undefined
            || (track as LocalVideoTrack).detach !== undefined);
    }
}

<div class="grid-container">
    <div class="grid-bottom-right">
        <a href="https://twitter.com/davidpine7" target="_blank"><i class="fab fa-twitter"></i> @davidpine7</a>
    </div>
    <div class="grid-left">
        <app-rooms #rooms (roomChanged)="onRoomChanged($event)"
                   [activeRoomName]="!!activeRoom ? activeRoom.name : null"></app-rooms>
    </div>
    <div class="grid-content">
        <app-camera #camera [style.display]="!!activeRoom ? 'none' : 'block'"></app-camera>
        <app-participants #participants
                          (leaveRoom)="onLeaveRoom($event)"
                          (participantsChanged)="onParticipantsChanged($event)"
                          [style.display]="!!activeRoom ? 'block' : 'none'"
                          [activeRoomName]="!!activeRoom ? activeRoom.name : null"></app-participants>
    </div>
    <div class="grid-right">
        <app-settings #settings (settingsChanged)="onSettingsChanged($event)"></app-settings>
    </div>
    <div class="grid-top-left">
        <a href="https://www.twilio.com/video" target="_blank">
            Powered by Twilio
        </a>
    </div>
</div>

.grid-container {
  display: grid;
  height: 100vh;
  grid-template-columns: 2fr 4fr 2fr;
  grid-template-rows: 1fr 7fr 1fr;
  grid-template-areas: "top-left . top-right" "left content right" "bottom-left . bottom-right";
}

.grid-content {
  grid-area: content;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: rgb(56, 56, 56);
  border-top: solid 6px #F22F46;
  border-bottom: solid 6px #F22F46;
}

.grid-left {
  grid-area: left;
  background: linear-gradient(to left, rgb(56, 56, 56) 0, transparent 100%);
  border-top: solid 6px #F22F46;
  border-bottom: solid 6px #F22F46;
}

.grid-right {
  grid-area: right;
  background: linear-gradient(to right, rgb(56, 56, 56) 0, transparent 100%);
  border-top: solid 6px #F22F46;
  border-bottom: solid 6px #F22F46;
}

.grid-top-left,
.grid-top-right,
.grid-bottom-left,
.grid-bottom-right {
  display: flex;
  justify-content: center;
  align-items: center;
}

.grid-top-left {
  grid-area: top-left;
}
.grid-top-right {
  grid-area: top-right;
}
.grid-bottom-left {
  grid-area: bottom-left;
}
.grid-bottom-right {
  grid-area: bottom-right;
}