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Re: [web-audio-api] (AudioGainScale): GainNode scale underdefined (#123)

From: Olivier Thereaux <notifications@github.com>
Date: Wed, 11 Sep 2013 07:29:43 -0700
To: WebAudio/web-audio-api <web-audio-api@noreply.github.com>
Message-ID: <WebAudio/web-audio-api/issues/123/24244338@github.com>
> [Original comment](https://www.w3.org/Bugs/Public/show_bug.cgi?id=17400#2) by Philip J├Ągenstedt on W3C Bugzilla. Tue, 12 Jun 2012 14:18:58 GMT

The question was answered (output = input * gain) but no normative requirements on implementations were added. We suggest avoiding phrasing like "will" or "is".

A "must" is missing in somewhere in the following:

"Every PCM audio sample in the input is multiplied by the gain parameter's value for the specific time corresponding to that audio sample. This multiplied value represents the PCM audio sample for the output. 

The number of channels of the output will always equal the number of channels of the input, with each channel of the input being multiplied by the gain values and being copied into the corresponding channel of the output."

They could also be replaced by something like "output[t] = gain[t] * input[t]" given some basic definitions to support it, but that is editorial.

Editorial issues:

"By default, it will take the input and pass it through to the output unchanged, which represents a constant gain change of 1." can be removed since it's already defined in the attributes section.

"As with other <code>AudioParams</code>, the <code>gain</code> parameter represents a mapping from time (in the coordinate system of AudioContext.currentTime) to floating-point value." can be moved to the AudioParam section since it is generally true, or removed.

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Received on Wednesday, 11 September 2013 14:34:40 UTC

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