Intent to Implement and Ship: Selective Disconnection on AudioNode.disconnect()

[Hongchan Choi]

Contact emails

hong...@chromium.org, rt...@chromium.org, cwi...@chromium.org

Spec

http://webaudio.github.io/web-audio-api/#idl-def-AudioNode

https://github.com/WebAudio/web-audio-api/issues/6

Summary

Currently AudioNode.disconnect() disconnects all existing connections out of node output(s). This change is to support disconnecting only one connection selectively.

Motivation

There have been numerous requests to support selective disconnection with disconnect() method and Audio WG agreed to change the spec to accommodate the feature request. With this change, it is possible to disconnect a signal path out of multiple connections to AudioNode input or AudioParam.

Currently the only way to disconnect one connection is to disconnect all the outputs and reconnect everything else except the connection to be dropped. This can cause audio glitches because it takes time to reconnect everything.

Compatibility Risk

None. We add new features to the existing disconnect() method and the change is backward-compatible. Mozilla also agreed with this change and will implement it in the near future.

Ongoing technical constraints

None.

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS,  and Android, and Android WebView)?

Yes.

OWP launch tracking bug?

https://code.google.com/p/chromium/issues/detail?id=448071

Link to entry on the feature dashboard

https://www.chromestatus.com/features/4793068276416512

Requesting approval to ship?

Yes

[Philip Jägenstedt]

LGTM

There's already a "disconnect (optional unsigned long output = 0)"
which confused me at first, but an AudioNode's output can be connected
to multiple other AudioNode or AudioNodes. This API allows you to
disconnect only one of those.

Philip

> To unsubscribe from this group and stop receiving emails from it, send an
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[Jochen Eisinger]

LGTM2

> email to blink-dev+unsubscribe@chromium.org.

[Dimitri Glazkov]

LGTM3

[Hongchan Choi]

Hello All,

While I was working on the actual implementation of this feature and I found some issues with the original proposal (which was approved by the spec WG). So I brought up the issue with the new proposal and it is approved by WG again today. WG agreed that this is a breaking change but the risk of compatibility is pretty low.

Please have a look at the new proposal (+ discussion) here: 

https://github.com/WebAudio/web-audio-api/pull/479#issuecomment-73742236

In short, the previous 'disconnect()' method was a bit broken. When the node has multiple outgoing connections and disconnects with no argument, it only disconnects the first output. (Because of optional = 0 in the method signature)

audioNode.disconnect(); // Currently it only disconnects the first output.

But with the new proposal, if the output index is unspecified then it disconnects all the connections at once.

audioNode.disconnect(); // (New) disconnects the all outgoing connections.

audioNode.disconnect(someNode); // (New) disconnects all the connections to the destination node.

Should I file the brand new intent email again? Or may I land the implementation to Blink with your approvals on this intent?

Thanks!

--

Hongchan Choi

Software Engineer

Google Chrome

http://hoch.io

[Dimitri Glazkov]

As long as Mozilla folks are on board, I think you could.

:DG<

[Hongchan Choi]

Yes - just got an LGTM from Paul (padenot@mozilla) on the new proposal.

Thanks Dimitri!