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Re: Detecting time-averaged levels

From: Chris Rogers <crogers@google.com>
Date: Fri, 3 Aug 2012 15:45:24 -0700
Message-ID: <CA+EzO0nK+V9kd8YcYMfCs7r=Y0AiuydjmfP+Pi4e-Lk5HYacpw@mail.gmail.com>
To: Joseph Berkovitz <joe@noteflight.com>
Cc: Audio Working Group <public-audio@w3.org>
On Fri, Aug 3, 2012 at 12:00 PM, Joseph Berkovitz <joe@noteflight.com>wrote:

> A number of scenarios in the Use Case document require a time-averaged
> level for some audio pathway -- maybe something like an RMS using a rolling
> average of squared signal values.
>
> Anyway, I'm wondering if I have missed any simple way of calculating such
> a level, or whether one must fall back to a JavaScriptAudioNode to do this.
>  It kind of seems natural for a RealtimeAnalyzerNode to do this even though
> it's not frequency-domain data.
>

You can do the "rolling average" with a ConvolverNode and do the squaring
with an AudioGainNode (feeding the input signal also to the .gain param).
Another way to do averaging is with one or more BiquadFilterNodes (as
low-pass filters).


>
> Regards,
>
> ... .  .    .       Joe
>
> *Joe Berkovitz*
> President
>
> *Noteflight LLC*
> Boston, Mass.
> phone: +1 978 314 6271
> www.noteflight.com
>
>
Received on Friday, 3 August 2012 22:45:53 GMT

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