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Re: How metering is calculated...
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Re: How metering is calculated...


  • Subject: Re: How metering is calculated...
  • From: Brian Willoughby <email@hidden>
  • Date: Mon, 1 Mar 2010 09:38:21 -0800

You left out a critical aspect of your algorithm. The 'M' in RMS stands for Mean, but you don't mention how you are calculating the mean. I suspect this is where your problem lies.

Also, I am surprised that you mention 'normalized.' In my book, that is a verb, so I am concerned that you are normalizing the values, which would alter them. In other words, 'normalized' usually refers to a process, so you should be clear as to whether you are processing the values in some way at that stage.

Brian Willoughby
Sound Consulting

On Feb 26, 2010, at 22:08, Grant Robinson wrote:
1) I am currently taking the RMS of the audio values normalized to the
range -1.0 to 1.0, and then converting that to a logarithmic scale
using the formula:

20 * log10(rms/base)

for base I have tried 0.775 and 0.5 trying to match the values I see
from CoreAudio.  Is this a valid approach?  If not, what sort of
calculation should I be doing?


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