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Re: [web-audio-api] Unclear semantics of duration param to AudioBufferSourceNode.start() (#71)

From: Olivier Thereaux <notifications@github.com>
Date: Wed, 11 Sep 2013 07:29:32 -0700
To: WebAudio/web-audio-api <web-audio-api@noreply.github.com>
Message-ID: <WebAudio/web-audio-api/issues/71/24244163@github.com>
> [Original comment](https://www.w3.org/Bugs/Public/show_bug.cgi?id=23007#0) by Ehsan Akhgari [:ehsan] on W3C Bugzilla. Mon, 19 Aug 2013 16:07:20 GMT

(In reply to comment #0)
> One reading of the optional "duration" parameter
> AudioBufferSourceNode.start() is that it is a kind of syntactic sugar in
> which
> 
>    node.start(startTime, offset, duration);
> 
> behaves the same as:
> 
>    node.start(startTime, offset);
>    node.stop(startTime + duration, offset);

Hmm, stop only accepts one argument, but yes, these should be the same in the non-looping mode.

> Another view is that the duration paramter has slightly different semantics
> from the stop/start delta, although exactly how it differs is unclear.
> Gecko's interpretation is reflected in this WebKit bug:
> 
>   https://bugs.webkit.org/show_bug.cgi?id=111952

> which states that the duration parameter is ignored if the buffer is in loop
> mode.

FWIW the spec is quite clear here: <https://bugs.webkit.org/show_bug.cgi?id=111952#c2>  It's just that WebKit doesn't implement what the spec requires correctly.

> My feeling is that the syntactic-sugar interpretation (duration is
> equivalent stop/start delta) is the cleanest, most obvious behavior and was
> probably the original intention of the parameter, however objectionable the
> sugar flavoring may be.

Really there is no good way to reconcile the duration argument with the loopStart and loopEnd attributes, as they're multiple ways of specifying the same thing...

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Received on Wednesday, 11 September 2013 14:33:07 UTC

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