Publishing

LocalPublisher is the single publishing surface for both engines.

final publisher = session.localPublisher!;

Switching sources without renegotiation

WHIP (RFC 9725) forbids changing media sections after the initial SDP, so the plugin never renegotiates. Track changes use replaceTrack:

await publisher.switchCamera(facing: CameraFacing.front);   // no ICE, no SDP
await publisher.startScreenShare();                          // adds a sender once
await publisher.stopScreenShare();                           // back to the camera

:::tip Keep the sender alive and only swap the track. Creating and closing senders on every switch is what causes “one second of black video” on WHIP servers. :::

Simulcast

Publishing always opens simulcast layers when the server supports them:

setPublishClarity only raises or lowers the top layer; lower layers stay available, so subscribers on slow links are never punished by the publisher’s choice.

await publisher.setPublishClarity(ClarityLevel.p720); // cap, do not restart

Bitrate and degradation

Let the server and the bandwidth estimator do the work. Only intervene when MediaHealthMonitor reports sustained congestion:

session.stats.listen((stats) {
  if (stats.packetLossPercent > 12) {
    unawaited(publisher.setPublishClarity(ClarityLevel.p360));
  }
});

Leaving the session

await publisher.stop();  // stops tracks, keeps the session alive
await session.leave();   // tears the whole thing down