The writable property of the MediaStreamTrackGenerator interface returns a WritableStream. This allows the writing of media frames to the MediaStreamTrackGenerator. The frames will be audio or video. The type is dictated by the kind of MediaStreamTrackGenerator that was created.

A WritableStream.

In the following example video frames are transformed then written to the WritableStream accessed with MediaStreamTrackGenerator.writable.

const trackProcessor = new MediaStreamTrackProcessor({ track: videoTrack });
const trackGenerator = new MediaStreamTrackGenerator({ kind: "video" });

/* */

trackProcessor.readable
  .pipeThrough(transformer)
  .pipeTo(trackGenerator.writable);