subscribeStreamManagerProxyTranscoderRTC

Subscribing to ABR Streams over Stream Manager Proxy with WebRTC

When a broadcast has the capability for Adaptive Bitrate (ABR) control, the consumed stream can dynamically switch variants based on the network conditions of the subscriber.

To start a subscription to a stream, request the ABR Provision of the target stream and select a variant to consume. Once the stream is being consumed, the server will update the variant and quality based on the network condition.

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The Stream Manager WebRTC proxy is a communication layer built inside streammanager web application which allows it to act as a proxy gateway for webrtc publishers / subscribers. The target use case of this communication layer is to facilitate a secure browser client to be able to connect to a "unsecure" remote websocket endpoint for consuming WebRTC services offered by Red5pro.

Stream Manager autoscaling works with dynamic nodes which are associated with dynamic IP addresses and cannot have a SSL attached to them. The proxy layer helps subscribers to connect and initiate a WebRTC subscribe session from a secure (ssl enabled) domain to a unsecure Red5pro origin having using an IP address.

Please refer to the Basic Subscriber Documentation to learn more about the basic setup.

In order to properly run the Stream Manager examples, you will need to configure you server for cluster infrastructure as described in the following documentation: https://www.red5.net/docs/installation/.

Server Configuration

Please read about WHIP/WHEP Configuration for Standalone and Stream Manager support.

Example Code

• index.html
• index.js

Setup

In order to subscribe to a stream that has an ABR provision, you will first need to request the Provision to get a list of variants that are available to subscribe to.

API

The API to POST a provision is as follows:

Authentication

Posting a Provision to the Stream Manager requires an authentication token. In order to obtain an authentication token, you will need to know the username and password associated with your Stream Manager deployment (replace yourstreammanager.com, smUsername, and smPassword):

const url = `https://${yourstreammanager.com}/as/v1/auth/login`
const token = 'Basic ' + btoa(`${smUsername}:${smPassword}`)
const response = await fetch(url, {
  method: 'PUT',
  withCredentials: true,
  credentials: 'include',
  headers: {
    Authorization: token,
    'Content-Type': 'application/json',
  },
})

console.log('Authenticate response: ' + response.status)
var json = await response.json()
return json.token

Endpoint

With the authentication token received, the following endpoint accepts a POST of JSON body explained in the next section. Replace yourstreammanager.com and nodeGroup with your Stream Manager deployment and the desired target node group, respectively. The streamGuid is the top-level streamGuid (pair of app context and stream name) of the provision being broadcast.

const url = `https://${yourstreammanager.com}/as/v1/streams/provision/${nodeGroup}/${streamGuid}`
const body = JSON.stringify(provision)
const result = await fetch(url, {
  method: 'GET',
  withCredentials: true,
  credentials: 'include',
  headers: {
    Authorization: `Bearer ${token}`,
    'Content-Type': 'application/json',
  },
})

The following section describes the response payload from the request. Note the top-level streamGuid defined - that value is the streamGuid used in the request URL.

JSON Schema Response

The basic JSON schema of the payload data for a provision has the following structure:

[
  {
    "streamGuid": "live/test",
    "streams": [
      {
        "streamGuid": "live/test_3",
        "abrLevel": 3,
        "videoParams": {
          "videoWidth": 320,
          "videoHeight": 180,
          "videoBitRate": 500000
        }
      },
      {
        "streamGuid": "live/test_2",
        "abrLevel": 2,
        "videoParams": {
          "videoWidth": 640,
          "videoHeight": 360,
          "videoBitRate": 1000000
        }
      },
      {
        "streamGuid": "live/test_1",
        "abrLevel": 1,
        "videoParams": {
          "videoWidth": 1280,
          "videoHeight": 720,
          "videoBitRate": 2000000
        }
      }
    ]
  }
]

Subscribing

The Provision returns a listing of stream variants with their unique streamGuid. The streamGuid is a path to the app context scope and stream name.

Subscribing to a stream variant is the same as subscribing to anyother stream from the Stream Manager - provide an endpoint to the proxy requesting the streamGuid from a variant:

const streamName = streamGuid.split('/').pop()
const endpoint = `https://${host}/as/v1/proxy/whep/${streamGuid}`

var rtcConfig = {
  ...configuration,
  ...defaultConfiguration,
  endpoint,
  streamName,
  subscriptionId: 'subscriber-' + instanceId,
  connectionParams: {
    ...connectionParams,
    nodeGroup,
  },
}

Once subscribed to a variant stream, the server will handle delivering the quality of stream from the ladder based on bandwidth estimation of the subscribing client.