## Sound Forge - PC

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 Subject:RMS algorithm Posted by: SonicCaveDan Date:10/14/2005 11:21:26 AM Is it possible to get the algorithm SF uses for deriving RMS values? Not sure how proprietary that is - it is a fairly standard algorithm though different applications use different varieties of the basic procedure. I need it to generate RMS values for large groups of files - it wouldn't work to have to load the files into SF one by one and scan them individually. Thanks for any info ... dwf Subject:RE: RMS algorithm Reply by: mpd Date:10/14/2005 2:02:57 PM To calculate rms, you calculate the squart root of the average of the squares. 1. Square the data: y[n] = x[n]^2 2. Compute the average: mu = (sum(i=1..N) y) / N 3.. Compute the suqre root: rms = sqrt(mu) Or roll it all together rms = sqrt((sum(i=1..N) x[n]^2) / N) Subject:RE: RMS algorithm Reply by: SonicCaveDan Date:10/18/2005 11:24:39 AM I've gotten that far. What I don't seem to have is the calculation to convert that do "dB down from 0 dB". There is also the question of windowing. One algorithm I saw uses 50ms windows, gets the RMS value for each window, sorts them, then takes the value 5% from the highest one. There are definitely a few ways to skin this cat and I'm hoping to zero in on the one SF uses - code would be great ... thanks dwf

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