Flutter

Getting started

📘

Before we start, you can find more information in the SDK Documentation which contains more examples and descriptions of the available modules.

Importing the library

You can import the SDK through flutter pub dev.

Import as a dependency

flutter pub add millicast_flutter_sdk

For windows you may need to allow installing apps from any source:

You should now see the follwing information in pubspec.yaml file:

dependencies:
    # ...
  # More dependencies
  millicast_flutter_sdk: ^0.2.x

And then using it with the import statement.

import 'package:millicast_flutter_sdk/millicast_flutter_sdk.dart';

Publish a stream

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You will need to find or create a new stream name with a token in your Millicast Dashboard. You can do that following this link.

The main module to publish a stream is the Publish module.

Instance the Publish module

To create a new publisher, you have to instance the Publish class:

import 'package:millicast_flutter_sdk/millicast_flutter_sdk.dart';

// Setting subscriber options
DirectorPublisherOptions directorPublisherOptions =
  DirectorPublisherOptions(
  token: 'my-publishing-token', streamName: 'my-stream-name');

// Define callback for generate new token`
tokenGenerator() => Director.getPublisher(directorPublisherOptions);

// Create a new instance
Publish millicastPublish =
  Publish(streamName: 'my-stream-name', tokenGenerator: tokenGenerator);

In order to create a Publish instance, you have to send two params.

  • The first one is the stream name ('my-stream-name') and it's used to set where do you want to publish your stream.
  • The second param is a callback (tokenGenerator) and it's used to get the necessary data of the stream name where you want to stream. Also, it's used to set auto reconnection if you are streaming and then lose connection. In order for the Director class to be able to call the getPublisher method for the tokenGenerator, you must first set the stream name ('my-stream-name') and token('my-publishing-token').

More information here:

Get your media information

You should get the media information (camera/microphone) you want to stream with. To do that, the SDK uses MediaStream object.

In this example, we are going to get the default user camera and microphone:

import 'package:flutter_webrtc/flutter_webrtc.dart';
// Get User camera and microphone
final _localRenderer = RTCVideoRenderer();
MediaStream? mediaStream = await navigator.mediaDevices.getUserMedia({
  'audio': true,
  'video': true,
});

This will ask permission in the mobile device to get the camera and microphone usage and will save the mediaStream information if the user accepts.

More information about using user media here:

Initialize the stream

After all previous steps are completed, you can now initialize the stream using the .connect() method inside the Publish module.

Using the instanced Publisher and mediaStream, add the connect method:

// Publishing Options
Map<String, dynamic> broadcastOptions = {'mediaStream': mediaStream};

_localRenderer.srcObject = mediaStream;

// Start connection to publisher
try {
  await millicastPublish.connect(options: broadcastOptions);
} catch (e) {
  throw Exception(e);
}

Once the .connect() Future resolves, the stream is initialized correctly; otherwise it'll throw an error.

The .connect() can optionally receive more params, all of which are described in the .connect() method.

For example:

  • If you want to start your stream with a bitrate limit, you can use the bandwidth option.

  • If your stream token in Millicast has the recording enabled, you can enable it with the record option. Once you have finished your stream, you can see the recording in the Dashboard Archive section.

  • You can start a stream without audio or video setting the disableAudio or disableVideo respectively.

  • You can select which codec you want to stream with using the codec option.

  • More information here:

  • .connect()

  • Dashboard Archive section

Managing your active stream

📘

The next samples use the publisher variable we created in the past steps. Please follow the tutorial.

The Publish instance internally uses most of the classes described in the documentation.
If the method is not static (which means you can access it without a Publish instance), you can access it through the Publish instance.

Example:

publisher.signaling   //corresponds to the Signaling module.
publisher.webRTCPeer  //corresponds to the Peerconnection module.

Most of the important methods are located directly in the Publisher module but some are not, like updating the bitrate or getting the WebRTC stats.

Change bitrate

During an active stream, you can limit the maximum bitrate in kbps.
To do that, you have to use the .updateBitrate() method of your Publish instance that is located inside a subclass called webRTCPeer.

Example:

publisher.webRTCPeer.updateBitrate(2000); //set the active stream with 2000 kbps limit.
publisher.webRTCPeer.updateBitrate(0);    //set the active stream with no limit.

More information here:

Stop stream

If you want to stop an active stream, you can use the .stop() method of your Publish instance.

publisher.stop()

More information here:

Viewer

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In order to connect to a stream you'll need the account id and stream name of the broadcast. This information must be provided by the publish owner.
Publish info Millicast Dashboard

The main module to view a stream is the View module.

Instance the View module

Creating a new View instance:

import 'dart:convert';
import 'package:flutter_webrtc/flutter_webrtc.dart';
import 'package:millicast_flutter_sdk/millicast_flutter_sdk.dart';

// Define callback for generate new token
DirectorSubscriberOptions directorSubscriberOptions =
  DirectorSubscriberOptions(
  streamName: 'my-stream-name',
  streamAccountId: 'my-stream-accountId');
tokenGenerator() => Director.getSubscriber(directorSubscriberOptions);

RTCVideoRenderer mediaStream = RTCVideoRenderer();

/// Create a new instance
View view =
  View(streamName: 'my-stream-name', tokenGenerator: tokenGenerator);

Just like in the case of creating a Publish instance, in order to create a View instance you need two params and there's also an optional param.
The first one is the stream name ('my-stream-name') and it's used to set the stream you want to connect.

  • The second param is a callback (tokenGenerator) and it's used to get the necessary data of the stream name where you want to connect. Also, it's used to set auto reconnection if you are streaming and then lose connection. You have to set the stream name('my-stream-name') and the token('my-subscriber-token') for the function to be able to be called correctly to generate the token.
  • (Optional) mediaElement. This is the HTML media element where you want to mount the stream; for example a video element.
  • (Optional) autoReconnect. The Default value is true, enabling auto reconnect to stream.

More information here:

  • View
  • .getSubscriber()
  • Token generator .callback()
mediaStream = RTCVideoRenderer();

/// Start connection to publisher
try {
  await view.connect();
  view.webRTCPeer.initStats();
  return view;
} catch (e) {
  throw Excpetion(e);
}

Track event

In case the mediaElement param is not specified when creating a View instance, a track event containing the media track will be emitted when the stream starts.

//...
view.on('stats', view, (ev, context) {
    MediaStream? stream = ev.eventData as MediaStream?;
    // Manage the track event.
});

Connecting to a stream

After the previous steps are done then you can connect to the stream using the .connect() method from the View instance.

try {
  await view.connect(options)
} catch (e) {
  print('Connection failed, handle error $e')
  view.reconnect();
}

We recommend using the .reconnect() method in the catch clause to make sure the View instance keeps trying to reconnect until the stream is live even when an error in the connect occurs.

Reconnect

Both the instances of Publish and View have a reconnect event. This event emits when the connection is lost with a timeout and error message in the callback. This event is emitted by the .reconnect() method, this method is automatically called by default except specified with the autoReconnect flag of the constructor. SDK Reconnect event

Example of a reconnect event in the View instance:

import 'package:millicast_flutter_sdk/millicast_flutter_sdk.dart';

View view = View(
    streamName: 'my-stream-name',
    tokenGenerator: tokenGenerator,
    mediaElement: localRenderer);

view.on('reconnect', view, (event, context) {
  print(event.eventData.toString());
});
  • The timeout is the time, in milliseconds, informing on when it will retry to establish the connection. It starts at 2000 ms and then 4000 ms ... until 32000 ms (32 s). After it reaches 32 s it starts retrying at 32 s intervals.
  • The error message contains the cause of failure.
    More information here:
  • Publish reconnect
  • View reconnect

Logger

You can get the logs of the connection, SDP, errors, and more. It can be enabled through the Logger module and you can activate it at any time (before/after a new connection).

import 'package:logger/logger.dart';
import 'package:millicast_flutter_sdk/millicast_flutter_sdk.dart';
Logger _logger = getLogger('main');
print(memory.getBuffer());

Where memory is a global variable in which all logs gets stored.

More information and examples here:

WebRTC Stats

Stream stats can be accessed by both Publish and View instances. In order to capture them, you have to initialize the stats and then listen for the event through the webRTCPeer attribute.

🚧

Stats might defer between different mobiles.

Example of usage:

import 'package:millicast_flutter_sdk/millicast_flutter_sdk.dart';

// Initialize and connect your Viewer
View view = View(
  streamName: Constants.streamName,
  tokenGenerator: tokenGenerator,
  mediaElement: localRenderer);

// Start connection to publisher
try {
  await view.connect();

  view.webRTCPeer.initStats();

  view.webRTCPeer.on('stats', view, (stats, context) {
    if (stats.eventData != null) {
      for (var report in stats.eventData as List<StatsReport>) {
        if (report.type != 'codec') {
          _logger.d('${report.id}, ${report.type}, ${report.timestamp}');
        }
      }
    }
  });
  return view;
} catch (e) {
  rethrow;
}

We highly recommend stopping the stats when they're not being used.

Example of stopping stats:

//...
view.webRTCPeer.stopStats();

More information here:

User count

Millicast server provides the number of current viewers through broadcast events. To start listening to different broadcast events you have to add which events you want to listen to in the Publisher/Subscriber options.

Both Publisher and Subscriber follow the same workflow.

Example of usage:

import 'package:millicast_flutter_sdk/millicast_flutter_sdk.dart';
import 'dart:convert';

//...
int _viewers;

// Add viewercount to events list
Map<String, dynamic> options = {
  'events': ['active', 'inactive', 'layers', 'viewercount']
};

await publish.connect(options: options);

// Add listener of broacastEvent to get UserCount
_publisherMedia.on('broadcastEvent', this, (event, context) {
  var data = jsonEncode(event.eventData);
  Map<String, dynamic> dataMap = jsonDecode(data);
  if (dataMap['name'] == 'viewercount') {
    _viewers = dataMap['data']['viewercount'];
    // Use _viewers value as needed
  }
});

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