VideoTrackGenerator

The VideoTrackGenerator interface of the Insertable Streams for MediaStreamTrack API has a WritableStream property that acts as a MediaStreamTrack source, by consuming a stream of VideoFrames as input.

Constructor

VideoTrackGenerator() Experimental

Creates a new VideoTrackGenerator object which accepts VideoFrame objects.

Instance properties

VideoTrackGenerator.muted Experimental

A Boolean property to temporarily halt or resume the generation of video frames in the output track.

VideoTrackGenerator.track Experimental

The output MediaStreamTrack.

VideoTrackGenerator.writable Experimental

The input WritableStream.

Examples

The following example is from the article Unbundling MediaStreamTrackProcessor and VideoTrackGenerator. It transfers a camera MediaStreamTrack to a worker for processing. The worker creates a pipeline that applies a sepia tone filter to the video frames and mirrors them. The pipeline culminates in a VideoTrackGenerator whose MediaStreamTrack is transferred back and played. The media now flows in real time through the transform off the main thread.

const stream = await navigator.mediaDevices.getUserMedia({ video: true });
const [track] = stream.getVideoTracks();
const worker = new Worker("worker.js");
worker.postMessage({ track }, [track]);
const { data } = await new Promise((r) => {
  worker.onmessage = r;
});
video.srcObject = new MediaStream([data.track]);

worker.js:

onmessage = async ({ data: { track } }) => {
  const vtg = new VideoTrackGenerator();
  self.postMessage({ track: vtg.track }, [vtg.track]);
  const { readable } = new MediaStreamTrackProcessor({ track });
  await readable
    .pipeThrough(new TransformStream({ transform }))
    .pipeTo(vtg.writable);
};

Specifications

Browser compatibility

See also

• MediaStreamTrackProcessor