RMS filter

naus3a · 2020-10-06T20:05:38.536Z

I’m still wrapping my head around Norns and, while I was fiddling around earlier today, I needed an RMS/ standard deviation calculator, so I made myself one, adding it to the filters lib.

It’s a tiny simple thing, but it’s a useful tool in dsp, so if anybody needs it, it’s here:

github.com

naus3a/NauNorns/blob/master/lib/moreFilters.lua

local Filters = require 'filters'

----------------------
--- @type Filters.rms
-- moving, windowed RMS/standard deviation filter

local rms = {}
rms.__index = rms
setmetatable(rms, { __index=Filters })

-- copying this is ugly; should figure out something different
-- helper to increment and wrap an index
local function wrap_inc(x, max)
   local y = x + 1
   while y > max do y = y - max end
   return y
end

----------------------
--- @type constructor

This file has been truncated. show original

if you include 'moreFilters', you’ll have all the standard norns filters + this new rms one; usage is the same as the other filters: you create a filter with a fixed window and you feed new samples:

local filters = include 'nau/lib/moreFilters'

local rms = filters.rms(20)
...
local curRms = rms:next(newSample, curMeanValue)

~~Also: I have no idea how to properly tag my post anybody willing to point me in the right direction?~~
thanks for editing it for me (stillgot the dumb and cannot see where the tag control is )