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Re: [web-audio-api] Need a way to determine AudioContext time of currently audible signal (#12)

From: Olivier Thereaux <notifications@github.com>
Date: Wed, 11 Sep 2013 07:29:25 -0700
To: WebAudio/web-audio-api <web-audio-api@noreply.github.com>
Message-ID: <WebAudio/web-audio-api/issues/12/24244090@github.com>
> [Original comment](https://www.w3.org/Bugs/Public/show_bug.cgi?id=20698#4) by Joe Berkovitz / NF on W3C Bugzilla. Tue, 02 Apr 2013 19:35:17 GMT

Ehsan, let me clarify the needs here with respect to the latency between the context's currentTime and the signal coming out of the sound card.

High accuracy for this use case is not needed. It's OK for screen updates to be slightly delayed for the purposes of seeing a cursor or pointer whose position over some sort of waveform or notated music reflects what one is hearing. These visual delays will not become really bothersome until they are consistently over 75ms or so.  And typically the DOM-to-screen display delay is much, much lower (more like the 16ms number you gave).

On the other hand these delays can be dwarfed by the currentTime-to-sound-card latency on some platforms, which can be as high as 200 or 300 ms. Having the cursor be misplaced by that amount is an experience-killer. That's why it's so important for an application to be able to acquire this number from the API: it's potentially much larger.

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Received on Wednesday, 11 September 2013 14:30:00 UTC

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