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Re: bump: AudioParam constructor

From: Chris Rogers <crogers@google.com>
Date: Mon, 19 Mar 2012 12:57:19 -0700
Message-ID: <CA+EzO0m1yNWVcs7DMi+eTAF8eedME9OdzB0k7qovKEavNDuqbQ@mail.gmail.com>
To: Jussi Kalliokoski <jussi.kalliokoski@gmail.com>
Cc: public-audio@w3.org
On Mon, Mar 19, 2012 at 11:51 AM, Jussi Kalliokoski <
jussi.kalliokoski@gmail.com> wrote:

> Hey group,
> Just thought I'd bring this up again, as I recently [1] told about the
> oscillator.js that adds an oscillator class to the AudioContext prototype.
> To refresh your memories of prior discussion: [2] [3] [4] [5] [6] [7] .
> So just wondering if there's any progress, the discussion sort of faded
> away then?
> Chris, I think the Float32Array containing the values matching sample
> times sounds like the most reasonable way to go right now. Either way, I
> still think we should expose this functionality to JavaScript nodes.
> Cheers,
> Jussi

Hi Jussi, yes I think it's an interesting idea and one idea to consider
could be something like:

partial interface AudioParam {

    double getValuesForTimeRange(startTime, endTime, defaultValue,
valuesArray, sampleRate);


One tricky thing is that the "timeline" values are stateful because of
the setTargetValueAtTime() method which does an exponential approach to a
desired value.  That's why I included the "defaultValue" and return value
above.  As an alternative, this default or current value can simply be
considered to be the "value" attribute and is kept in the AudioParam
itself, but then it's still necessary to be aware of the statefulness,
since in that case getValuesForTimeRange() would be expected to be called
on successive continuous time ranges, and you couldn't just call it in a
"random-access" way...

It's a bit tweaky and there's a bit to think about here, but interesting


> [1] http://lists.w3.org/Archives/Public/public-audio/2012JanMar/0374.html
> [2] http://lists.w3.org/Archives/Public/public-audio/2011AprJun/0085.html
> [3] http://lists.w3.org/Archives/Public/public-audio/2011AprJun/0086.html
> [4] http://lists.w3.org/Archives/Public/public-audio/2011AprJun/0087.html
> [5] http://lists.w3.org/Archives/Public/public-audio/2011AprJun/0089.html
> [6] http://lists.w3.org/Archives/Public/public-audio/2011AprJun/0101.html
> [7] http://lists.w3.org/Archives/Public/public-audio/2011AprJun/0103.html
Received on Monday, 19 March 2012 19:57:48 UTC

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