RTCTransformEvent
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
The RTCTransformEvent
of the WebRTC API represent an event that is fired in a dedicated worker when an encoded frame has been queued for processing by a WebRTC Encoded Transform.
The interface has a transformer
property that exposes a readable stream and a writable stream.
A worker should read encoded frames from transformer.readable
, modify them as needed, and write them to transformer.writable
in the same order and without any duplication.
At time of writing there is just one event based on RTCTransformEvent
: rtctransform
.
Instance properties
Since RTCTransformEvent
is based on Event
, its properties are also available.
RTCTransformEvent.transformer
Read only-
Returns the
RTCRtpScriptTransformer
associated with the event.
Transform event types
There is only one type of transform event.
rtctransform
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.
Example
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.
Specifications
Specification |
---|
WebRTC Encoded Transform # rtctransformevent |
Browser compatibility
BCD tables only load in the browser