Allow transferring ArrayBuffer into WebCodecs object constructors

[Djuffin]

こんにちは TAG-さん!

I'm requesting a TAG review of "Allow transferring ArrayBuffer into WebCodecs object constructors".

We're working on adding transferable buffers to WebCodecs object constructors. We've copied the transfer-list approach used by structuredClone and postMessage.

However a concern have been raised that this mechanism isn't ideal: Should we just use a boolean value instead of a transfer list to indicate transferring of the ArrayBuffer contents to a WebCodecs object. Arguments:

• Boolean is easier to use and understand for API users.
• Transfer list can be extended in the future when WebCodec objects need to transfer more than one ArrayBuffer ( we are likely to accept arrays of metadata, HDR data, etc. )
• Transfer list is consistent with existing APIs like structuredClone and postMessage.

We've been asked to solicit TAG guidance on whether copying this mechanism is appropriate in terms of TAG principles around consistency.

• Explainer¹ (minimally containing user needs and example code): https://gist.github.com/Djuffin/1c8fac486ca9f402be85074166e89a16
• Specification URL: https://www.w3.org/TR/webcodecs/#dictdef-videoframeinit
• Tests: https://github.com/web-platform-tests/wpt/tree/master/webcodecs
• User research: [url to public summary/results of research]
• Primary contacts (and their relationship to the specification):
  • Eugene Zemtsov ( @Djuffin ) Google LLC
• Organization(s)/project(s) driving the specification: Chromium
• External status/issue trackers for this specification (publicly visible, e.g. Chrome Status): https://chromestatus.com/feature/5075602045927424

Further details:

• [x ] I have reviewed the TAG's Web Platform Design Principles
• The group where the work on this specification is currently being done: Media Working Group

We'd prefer the TAG provide feedback as (please delete all but the desired option):

💬 leave review feedback as a comment in this issue and @-notify @Djuffin

[torgo]

Hi @Djuffin

My apologies it's taken us so long to get back to you on this. I realize things may have moved on significantly since you filed this review. We did have a fairly detailed discussion on this review in October but unfortunately the output didn't make its way into this issue. Specifically you've asked "Should we just use a boolean value instead of a transfer list to indicate transferring of the ArrayBuffer contents to a WebCodecs object". In the absence of our feedback have you made any decision in the group thus-far on this? In any case, we don't see any issues and we're happy with the multi-stakeholder story here.

[Djuffin]

Thank you!

The change has been merged to the webcodecs spec and released in Chromium

[torgo]

Thanks @Djuffin we're happy to close on this basis.