Specify and implement transferable streams

[guest271314]

Describe the feature
The comparision between using transferring a single stream (ReadableStream; WritableStream) and transferring hundreds of thousands of TypedArrays using MessagePort.postMessage() is not even close.

AudioWorklet invariably outputs multiple gaps of silence at both Chromium and Firefox when thousands of messages are posted/TypedArrays transferred.

Is there a prototype?

Yes.

• https://docs.google.com/document/d/1_KuZzg5c3pncLJPFa8SuVm23AP4tft6mzPCL5at3I9M/edit
• https://bugs.chromium.org/p/chromium/issues/detail?id=894838

Describe the feature in more detail

See https://bugs.chromium.org/p/chromium/issues/detail?id=910471#c11.

Posting a single ReadableStream, e.g., from a TransformStream substantially reduces observable gaps in playback to 1 (that bug is currently isolated to being observable at the end of reading/writing the stream, not the underlying network request in the code used to get the stream) from multiple gaps randomly occurring during playback https://bugzilla.mozilla.org/show_bug.cgi?id=1629384#c24.

Compare for yourself https://plnkr.co/edit/nECtUZ (transferable streams implemented at Chromium behind --enable-experimental-web-platform-features); https://plnkr.co/edit/yh5A66UhMnlpq0JF (thousands of postMessage(<TypedArray>, [<TypedArray.buffer>]) calls).

[padenot]

Virtual F2F:

• Dupe of can streams be transferred via postMessage()? whatwg/streams#276.

[guest271314]

@padenot

Perhaps the Virtual F2F participants did not understand the Issue.

Am stating MessagePort does not work without gaps in audio output for substantial amount of input data.

Get rid of MessagePort altogether and substitute a TransformStream

Main thread context (WritableStream) <= TransformStream => AudioWorkletProcessor (AudioWorkletGlobalScope``) context (ReadableStream`)