Re: Getting average power / peak power (sound monitoring)
Re: Getting average power / peak power (sound monitoring)
- Subject: Re: Getting average power / peak power (sound monitoring)
- From: "Neil Clayton" <email@hidden>
- Date: Tue, 20 Jun 2006 13:10:51 +0100 (BST)
- Importance: Normal
Haha. Thanks. That's useful, I might take a look at that, purely from a
learning perspective. Strangely enough, it does sound fun!
The bigger question is - where do I get the samples from, for the incoming
audio?
> on 06/06/19 12:45, Neil Clayton at email@hidden wrote:
>
>> Does anyone know how to get a level (avg power, peak power) meter
>> reading from some kind of sound input device?
>
> If CoreAudio is too heavyweight, and no one on the list offers a better
> solution, you roll your own algorithm...
>
> Average Power: Average of the squares of the magnitude samples over a
> given
> period, the "window". In real time, as each new sample appears, you
> subtract the oldest sample from the sum and add in the new one. For
> further
> smoothing, process the result with an first-order infinite impules
> response
> (IIR) filter.
>
> Peak Power: Same idea, except you use the maximum of the squares
> (MAX(newSampleSquared,oldMaxSquare)) instead of their average.
>
> In either case, you adjust the window length and IIR filter time constant
> ("beta" factor) to get the desired smoothing, which depends on how often
> you're going to update your display.
>
> Probably the most fun you'll have all week!
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