DedicatedWorkerGlobalScope: rtctransform event

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("rtctransform", (event) => { })

onrtctransform = (event) => { }

Event type

A RTCTransformEvent. Inherits from Event.

Event properties

This interface also inherits properties from its parent, Event.

RTCTransformEvent.transformer Read only

Returns the RTCRtpScriptTransformer associated with the event.

Example

The following code snippet shows a handler for the rtctransform event in the worker, added to the global scope using addEventListener(). The event.transformer is a RTCRtpScriptTransformer, the worker side counterpart to RTCRtpScriptTransform.

addEventListener("rtctransform", (event) => {
  let transform;
  // Select a transform based on passed options
  if (event.transformer.options.name === "senderTransform")
    transform = createSenderTransform(); // A TransformStream
  else if (event.transformer.options.name === "receiverTransform")
    transform = createReceiverTransform(); // A TransformStream
  else return;

  // Pipe frames from the readable to writeable through TransformStream
  event.transformer.readable
    .pipeThrough(transform)
    .pipeTo(event.transformer.writable);
});

The rtctransform event is fired when an encoded frame is enqueued on the RTCRtpScriptTransformer and just once when the transformer's corresponding RTCRtpScriptTransformer is constructed. The code first determines what transform to apply using name value passed in the options (this allows RTCRtpScriptTransform instances added to the incoming and outgoing WebRTC pipelines to share a single worker). Encoded frames are then piped from the readable, through the selected transform TransformStream, to a writeable. The actual transforming code is not shown.

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

Specifications

Browser compatibility

See also

• Using WebRTC Encoded Transforms