You can utilize either the WHIPClient or RTCPublisher from the SDK to start a broadcast for ABR:

WHEPClient

With the WHEPClient, the negotiation sequence with a Stream Manager is handled server side. As such, it is very similar to how you would normally publish to the server:

import { WHIPClient } from "red5pro-webrtc-sdk";

const publish = async () => {
  const publisher = new WHIPClient();
  await publisher.init({
    endpoint: `https://myred5.cloud.red5.net/as/v1/proxy/whip/live/mystream`,
    connectionParams: {
      nodeGroup: "my-node-group",
      transcode: true,
    },
    streamName: "mystream",
    mediaConstraints: {
      audio: true,
      video: {
        width: 1280,
        height: 780,
        frameRate: 60,
      },
    },
    bandwidth: {
      audio: 128,
      video: 2000,
    },
  });
  await publisher.publish();
};

The above is a very basic configuration. Your webapp may need additional configurations depending on requirements and deployment.

Note the mediaContraints object on the initialization configuration and that it defines the video contraint with the corresponding variant qualities for mystream from the above examples. This will be used in accessing the getUserMedia of the browser client.