Mediasoup : Link audio/video streams with participants

index.js

// You need to setup a working mediasoup SFU server first
// see : https://mediasoup.org/api/#webrtc

// Map userId => streamId 
// Local to a room
const userStreams = {};

// Mediasoup peer
const mediaPeer = mediaRoom.Peer(participant.id);

// New stream added to the room. Can be either audio or video.
// Will be call twice if video & audio
mediaPeer.on('newrtpsender', (rtpSender) => {
  // Stream id i.e client MediaStream.id
  const msid = rtpSender.rtpParameters.userParameters.msid.split(/\s/)[0];
  // Stream's owner
  const ownerPeer = rtpSender.associatedPeer;
  // Owner's id
  const ownerId = ownerPeer.name;
  // Add stream to map
  const added = newStream({ streamId : msid, ownerId });
  // Send map only if something has changed in userStreams map
  if (added) {
    userStreamMapUpdate(appRoom.getParticipantsWithoutUser({ id : ownerId }));
  }
});

function newStream({ streamId, ownerId }) {
  if (!this.userStreams[ownerId]) {
    this.userStreams[ownerId] = [streamId];
    return true;
  }
  const streams = this.userStreams[ownerId];
  // Avoid duplicates
  // Handle audio & video as an unique stream
  if (!streams.includes(streamId)) {
    streams.push(streamId);
    return true;
  }
  return false; 
}

function userStreamMapUpdate(participants) {
  // Send new map value to all room participants
  participants.forEach(({ socket }) => socket.emit('stream:update', { userStreams }));
}

Hi, just one consideration. I've modified the API, so rtpSender.associatedPeer no longer exists. Instead, now there is:

rtpReceiver.peer  // The Peer owner of the RtpReceiver
rtpSender.peer  // The Peer owner of the RtpSender
rtpSender.associatedRtpReceiver  // The associated RtpReceiver that triggered the creation of this RtpSender

The doc is updated: https://mediasoup.org/api/