RTCTransformEvent

Since RTCTransformEvent is based on Event, its properties are also available.

RTCTransformEvent.transformer Read only

Returns the RTCRtpScriptTransformer associated with the event.

There is only one type of transform event.

The rtctransform event is fired at the worker global scope on construction of an associated RTCRtpScriptTransform, and whenever a new encoded video or audio frame is enqueued for processing.

You can add a rtctransform event listener to be notified when the new frame is available using either DedicatedWorkerGlobalScope.addEventListener() or the onrtctransform event handler property.

This example creates an event listener for the rtctransform event.

The example assumes we have a TransformStream with an options object passed from a RTCRtpScriptTransform constructor in the main-thread. The code at the end shows how the stream is piped through the transform stream from the readable to the writable.

addEventListener("rtctransform", (event) => {
  let transform;
  // Select a transform based on passed options
  if (event.transformer.options.name == "senderTransform") {
    transform = createSenderTransform(); // A TransformStream (not shown)
  } else if (event.transformer.options.name == "receiverTransform") {
    transform = createReceiverTransform(); // A TransformStream (not shown)
  }
  // Pipe frames from the readable to writeable through TransformStream
  event.transformer.readable
    .pipeThrough(transform)
    .pipeTo(event.transformer.writable);
});

Note that this code is part of a more complete example provided in Using WebRTC Encoded Transforms.