Re: [Minutes] TPAC 6-7 November 2017 SF

Thanks so much for the nice write-up, Joe!

On Wed, Nov 8, 2017 at 8:03 AM Joe Berkovitz <joe@noteflight.com> wrote:

> Hi all,
>
> It's been a great meeting this year at TPAC. Here is a rough summary of
> the ground we covered (at least, the part for which I was able to be
> present).
>
> - Our CR transition request is in progress and a final review has been
> requested from the TAG.
>
> - Further work on populating the test suite was planned.
>
> - All v.next milestone issues have been reviewed. A rough cut at a set of
> high priority issues was identified by the group. Also, some issues were
> clarified and/or closed during this review.
>
> - We have three remaining issues with the spec language for AudioWorklet
> and its friends which we expect to close within the week:
>
>    -- #1435 is the most substantive of the three issues. It relates to the
> initialization sequence for AudioWorkletGlobalScopes and the question of
> the relationship of such scopes to their owning AudioContexts. We conferred
> with Ian Kilpatrick and after much discussion arrived at the conclusion
> that global scopes must be created in a way that unambiguously identifies
> the owning context. In this way, each addModule() call is specific to a
> context, and results in a promise that resolves only after all processor
> classes have been registered for that context. This requires that we move
> the audioWorklet attribute out of Window and into BaseAudioContext.
>
>   -- #1441 is a minor typo.
>
>   -- #1442 is an omission of the serialization/passthrough of a new
> AudioWorkletNode's options dictionary, which was supposed to be
> communicated to the associated AudioWorkletProcessor. It is easy to add the
> missing language.
>
> - We met with the WebAssembly CG to discuss how to best support
> AudioWorkletProcessor with WASM code. The discussion had several facets:
>
>    -- Both groups affirmed that WebAssembly and AudioWorklet together have
> a very strong set of combined use cases.
>
>    -- A demo of FM synthesis using WASM and the current Chrome Canary
> AudioWorklet implementation was shown. The integration wasn't an example of
> best practices but it showed feasibility.
>
>    -- We discussed the need for a clean way to load WASM modules directly
> into AudioWorklets via addModule(). Perhaps these could register their own
> processors through Web Audio APIs exported for visibility within WASM.
> However the JS-class-based approach in the current AudioWorkletProcessor
> may be a poor fit.
>
>    -- A shorter-term approach to surfacing WASM in AudioWorklets is to
> construct a Module on the main thread and serialize it through the
> AudioWorkletNode at construction time, instantiating it on the audio thread
> side if it doesn't already exist there. The serialization and instantiation
> of modules are expected to be lightweight operations.
>
>    -- The current approach in which the audio thread owns the array
> buffers used to communicate with an AudioWorkletProcessor imposes the need
> for unnecessary copying of data, since those buffers can't be directly seen
> by WASM. We talked about an alternative approach in which WASM (or perhaps,
> even JS processors) provisions the buffers to the engine itself. This
> requires an alternative protocol in which the engine states its needs and
> the processor fulfills them, so it will require a fair bit of thinking
> together.
>
>    -- We would like to follow up with further joint Web Audio /
> WebAssembly meetings preceded by a call for concrete proposals on the above
> points.
>
> Let me know if I omitted anything. And thanks again everyone for a great
> TPAC.
>
> Best,
>
> .            .       .    .  . ...Joe
>
> Joe Berkovitz
> Founder
> Noteflight LLC
>
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