Using the Network Quality API

概要

This guide introduces the Network Quality API and provides guidance on how to use it effectively in your Twilio Video applications. The Network Quality API is only available in Group Rooms.

目次

• What's The Network Quality API
• Using the Network Quality API
  • Enabling Network Quality Reporting
  • Receiving the Network Quality Level
• 既知の問題

What's the Network Quality API

In a video application, the perceptual quality experienced by a Participant can be greatly influenced by the network. Degradation of available bandwidth, packet loss, or network jitter may reduce the usability of a video conferencing link causing end-user frustration. To tackle this, the Network Quality API monitors the Participant's network and provides quality metrics. Displaying quality scores in your UI can aid users in diagnosing problems as their network environment changes (such as due to a Wifi to Cellular handoff).

For this, the Network Quality API uses an algorithm that ingests both Client and Server metrics and computes a Network Quality Level on the following Likert scale:

Remark that the Network Quality Level is not an absolute metric but a score relative to what you are demanding from the network. For example, it may happen that your Quality Level is 5 while you are communicating low quality video but it drops to 1 as soon as you change the video to be HD even if the network does not change at all in the process.

This also means that when you are not using the network at all (i.e. you are neither publishing nor subscribing to any Tracks) your quality level will be always 5 given that any network will be capable of complying with a zero communications demand.

Using the Network Quality API

Enabling Network Quality Reporting

The Network Quality API is disabled by default, and is requested at connect time. The following table illustrates the currently supported platforms:

The Network Quality API is only available Group Rooms (including Small Group Rooms).

iOS

When building TVIConnectOptions, set the property networkQualityEnabled to true.

let options = TVIConnectOptions(token: accessToken) { (builder) in
    builder.networkQualityEnabled = true
    builder.roomName = "my-room"
}

room = TwilioVideo.connect(with: options, delegate: self)

JavaScript

In JavaScript, you can use the following code snippet for enabling the Network Quality API:

    var Video = require('twilio-video');
    var token = getAccessToken();

    // Connect with custom names for LocalAudioTrack and LocalVideoTrack
    Video.connect(token, {
      name: 'my-room',
      audio: { name: 'microphone'},
      video: { name: 'camera'},
      networkQuality: true
    }).then(function(room) {
      room.localParticipant.trackPublications.forEach(function(publication) {
        console.log('The LocalTrack "' + publication.trackName + '" was successfully published');
      });
    });

Receiving the Network Quality Level

Once the Network Quality API is enabled through the connect method as shown above, the SDK will start receiving Network Quality Level events. That Network Quality Level is a value from 0–5, inclusive, representing the quality of the network connection of the Participant, as illustrated in the table above. Note that while a Room is in the reconnecting state, a LocalParticipant's Network Quality Level is set to 0.

The specific value of the Network Quality Level can be obtained at any time using the networkQualityLevel property of the LocalParticipant object. Also note that while a Room is in reconnecting state, the LocalParticipant's Network Quality Level is 0.

In addition, applications can get notified of changes on the networkQualityLevel by subscribing to the networkQualityLevelChanged event that is published by the LocalParticipant.

iOS

Implement -[TVILocalParticipantDelegate localParticipant:networkQualityLevelDidChange:] in order to respond to speaker events.

// MARK: TVILocalParticipantDelegate
func localParticipant(_ participant: TVILocalParticipant, 
                      didChange networkQualityLevel: TVINetworkQualityLevel) {

    print("Network Quality Level Changed: \(networkQualityLevel)")
}

JavaScript

A typical way of using the Network Quality Level is to represent a Participant's Network Quality as cell phone-style signal-strength bars. The following snippet shows how to do it in JavaScript:

    //Print in console the networkQualityLevel using bars
    function printNetworkQualityLevel(networkQualityLevel) {
      console.log({
        1: '▃',
        2: '▃▄',
        3: '▃▄▅',
        4: '▃▄▅▆',
        5: '▃▄▅▆▇'
      }[networkQualityLevel] || '');
    }

    // Print the initial Network Quality Level
    printNetworkQualityLevel(participant.networkQualityLevel);

    // Print changes to Network Quality Level
    participant.on('networkQualityLevelChanged', printNetworkQualityLevel);

既知の問題

• This API is not currently available on Android
• The networkQualityLevel property and the networkQualityLevelChanged event are only available for the LocalParticipant. Future releases will provide scores for RemoteParticipant as well.