Kraken

🐙 High performance WebRTC audio SFU implemented with pure Go.

Architecture

Kraken SFU only supports simple group audio conferencing, more features may be added easily.

Both Unified Plan and RTCP-MUX supported, so that only one UDP port per participant despite the number of participants in a room.

monitor [WIP]

This is the daemon that load balance all engine instances according to their system load, and it will direct all peers in a room to the same engine instance.

engine

The engine handles rooms, all peers in a room should connect to the same engine instance. No need to create rooms, a room is just an ID to distribute streams.

Access the engine with HTTP JSON-RPC, some pseudocode to demonstrate the full procedure.

var roomId = getUrlQueryParameter('room');
var userId = uuidv4();
var trackId;

var pc = new RTCPeerConnection(configuration);

// send ICE candidate to engine
pc.onicecandidate = ({candidate}) => {
  rpc('trickle', [roomId, userId, trackId, JSON.stringify(candidate)]);
};

// play the audio stream when available
pc.ontrack = (event) => {
  el = document.createElement(event.track.kind)
  el.id = aid;
  el.srcObject = stream;
  el.autoplay = true;
  document.getElementById('peers').appendChild(el)
};

// setup local audio stream from microphone
const stream = await navigator.mediaDevices.getUserMedia(constraints);
stream.getTracks().forEach((track) => {
  pc.addTrack(track, stream);
});
await pc.setLocalDescription(await pc.createOffer());

// RPC publish to roomId, with SDP offer
var res = await rpc('publish', [roomId, userId, JSON.stringify(pc.localDescription)]);
// publish should respond an SDP answer
var jsep = JSON.parse(res.data.jsep);
if (jsep.type == 'answer') {
  await pc.setRemoteDescription(jsep);
  trackId = res.data.track;
  subscribe(pc);
}

// RPC subscribe to roomId periodically
async function subscribe(pc) {
  var res = await rpc('subscribe', [roomId, userId, trackId]);
  var jsep = JSON.parse(res.data.jsep);
  if (jsep.type == 'offer') {
    await pc.setRemoteDescription(jsep);
    var sdp = await pc.createAnswer();
    await pc.setLocalDescription(sdp);
    // RPC anwser the subscribe offer
    await rpc('answer', [roomId, userId, trackId, JSON.stringify(sdp)]);
  }
  setTimeout(function () {
    subscribe(pc);
  }, 3000);
}

async function rpc(method, params = []) {
  const response = await fetch('http://localhost:7000', {
    method: 'POST',
    mode: 'cors',
    headers: {
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({id: uuidv4(), method: method, params: params})
  });
  return response.json();
}

Quick Start

Setup Golang development environment at first.

git clone https://github.com/MixinNetwork/kraken
cd kraken && go build

cp config/engine.example.toml config/engine.toml
ip address # get your network interface name, edit config/engine.toml

./kraken -c config/engine.toml -s engine

Get the source code of either kraken.fm or Mornin, follow their guides to use your local kraken API.

Community

Kraken is built with Pion, we have discussions over their Slack.