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Re: Web Audio API sequencer capabilities

From: Chris Rogers <crogers@google.com>
Date: Mon, 8 Oct 2012 12:20:03 -0700
Message-ID: <CA+EzO0kBaGMNjwNQZ6eXnDJyVKKmi3rWtaDhWTs7qYn-6ZQEEQ@mail.gmail.com>
To: Srikumar Karaikudi Subramanian <srikumarks@gmail.com>
Cc: Joe Berkovitz <joe@noteflight.com>, Jussi Kalliokoski <jussi.kalliokoski@gmail.com>, "public-audio@w3.org Group" <public-audio@w3.org>
On Fri, Oct 5, 2012 at 9:03 PM, Srikumar Karaikudi Subramanian <
srikumarks@gmail.com> wrote:

> On 6 Oct, 2012, at 4:27 AM, Joe Berkovitz <joe@noteflight.com> wrote:
>
> Actually, I didn't ever think a GainNode would generate its own signal.
> Rather, it did not occur to me to drive a set of AudioParams with an
> envelope via the audio rate modulation feature, using a gain controlled
> unity signal. It is this last idea that seems a bit tricky and unclear for
> API novices. If there were something like a UnitySourceNode, I would feel
> better.
>
> Chris R - I see that the AudioBufferSourceNode's 'gain' attribute was
> removed from the spec in Apr '11 (
> https://dvcs.w3.org/hg/audio/file/908b6b7b8702/webaudio/specification.html),
> but it is present in all webkit implementations even today, including
> Chrome Canary. In
> http://lists.w3.org/Archives/Public/public-audio/2012AprJun/0072.html,
> you wrote -- "We may need to re-visit the removal of these gain
> attributes from the API, since I've found several pages out in the wild
> using them. They're not harmful attributes, just ones I felt could be
> cleaned up (removed) since AudioGainNode can be used instead. We may need
> to choose a deprectation path, or simply keep them."
>
> With the 'gain' parameter, the AudioBufferSourceNode would offer a single
> node solution to envelope generation. You can set a one sample buffer with
> sample value = 1, turn on looping and work with its gain parameter. This is
> simple enough that a special UnitySourceNode and an EnvelopeNode would be
> superfluous. (I only just realized I've been using the ABSN this way
> instead of the "GainNode with unity signal" approach I mentioned earlier ..
> but was surprised to find that the ABSN.gain parameter was removed from the
> spec.)
>
> AudioBuffer.gain and AudioListener.gain are likely to be superfluous, but
> if AudioBufferSourceNode.gain is removed, a gain node seems likely to be
> necessary most of the time anyway. Given that the ability to connect a node
> to an AudioParam didn't exist when the ABSN.gain parameter was removed, it
> is worth reconsidering it in the context of envelopes as well.
>
>
Hi Kumar, I think it's best to keep the AudioBufferSourceNode API simpler.
 It's only two or three more lines of JS to create the AudioGainNode and
connect it.
Received on Monday, 8 October 2012 19:20:30 UTC

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