49 lines
1.3 KiB
Nim
49 lines
1.3 KiB
Nim
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## Dynamic Smoothing Using Self Modulating Filter
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## Andrew Simper, Cytomic, 2014, andy@cytomic.com
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## public release: 6th Dec 2016
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## https://cytomic.com/files/dsp/DynamicSmoothing.pdf
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type
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DynParamSmooth* = object
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baseFreq: float
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sensitivity: float
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wc: float
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low1: float
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low2: float
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inz: float
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proc reset*(self: var DynParamSmooth) =
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self.low1 = 0.0
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self.low2 = 0.0
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self.inz = 0.0
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proc setSampleRate*(self: var DynParamSmooth, sampleRate: float) =
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self.wc = self.baseFreq / sampleRate
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self.reset()
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proc process*(self: var DynParamSmooth, sample: float): float =
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let low1z = self.low1
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let low2z = self.low2
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let bandz = low1z - low2z
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let wd = self.wc + self.sensitivity * abs(bandz)
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let g = min(wd * (5.9948827 + wd * (-11.969296 + wd * 15.959062)), 1.0)
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self.low1 = low1z + g * (0.5 * (sample + self.inz) - low1z)
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self.low2 = low2z + g * (0.5 * (self.low1 + low1z) - low2z)
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self.inz = sample
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return self.low2
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proc initDynParamSmooth*(
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baseFreq: float = 2.0,
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sensitivity: float = 2.0,
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sampleRate: float = 48_000.0
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): DynParamSmooth =
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result.baseFreq = baseFreq
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result.sensitivity = sensitivity
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result.wc = result.baseFreq / sampleRate
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result.reset()
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