parent
3605d6b6a8
commit
4cf6145888
@ -1,89 +0,0 @@ |
|||||||
/*
|
|
||||||
* DCfilter.h |
|
||||||
* |
|
||||||
* Copyright 2012 Tim Barrass. |
|
||||||
* |
|
||||||
* This file is part of Mozzi. |
|
||||||
* |
|
||||||
* Mozzi is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. |
|
||||||
* |
|
||||||
*/ |
|
||||||
|
|
||||||
#ifndef DCFILTER_H |
|
||||||
#define DCFILTER_H |
|
||||||
|
|
||||||
/*
|
|
||||||
tb2010 adapted from: |
|
||||||
robert bristow-johnson, DSP Trick: Fixed-Point DC Blocking Filter with Noise-Shaping |
|
||||||
http://www.dspguru.com/book/export/html/126
|
|
||||||
|
|
||||||
y[n] = x[n] - x[n-1] + a * y[n-1] |
|
||||||
|
|
||||||
Where y[n] is the output at the current time n, and x[n] is the input at the current time n. |
|
||||||
|
|
||||||
also, see DC Blocker Algorithms, http://www.ingelec.uns.edu.ar/pds2803/materiales/articulos/04472252.pdf
|
|
||||||
*/ |
|
||||||
|
|
||||||
/**
|
|
||||||
A DC-blocking filter useful for highlighting changes in control signals. |
|
||||||
The output of the filter settles to 0 if the incoming signal stays constant. If the input changes, the |
|
||||||
filter output swings to track the change and eventually settles back to 0. |
|
||||||
*/ |
|
||||||
class DCfilter |
|
||||||
{ |
|
||||||
public: |
|
||||||
/**
|
|
||||||
Instantiate a DC-blocking filter. |
|
||||||
@param pole sets the responsiveness of the filter, |
|
||||||
how long it takes to settle to 0 if the input signal levels out at a constant value. |
|
||||||
*/ |
|
||||||
DCfilter(float pole):acc(0),prev_x(0),prev_y(0) |
|
||||||
{ |
|
||||||
A = (int)(32768.0*(1.0 - pole)); |
|
||||||
} |
|
||||||
|
|
||||||
/* almost original
|
|
||||||
// timing: 20us
|
|
||||||
int next(int x) |
|
||||||
{ |
|
||||||
setPin13High(); |
|
||||||
acc -= prev_x; |
|
||||||
prev_x = (long)x<<15; |
|
||||||
acc += prev_x; |
|
||||||
acc -= A*prev_y; |
|
||||||
prev_y = acc>>15; // quantization happens here
|
|
||||||
int filtered = (int)prev_y; |
|
||||||
// acc has y[n] in upper 17 bits and -e[n] in lower 15 bits
|
|
||||||
setPin13Low(); |
|
||||||
return filtered; |
|
||||||
} |
|
||||||
*/ |
|
||||||
|
|
||||||
/**
|
|
||||||
Filter the incoming value and return the result. |
|
||||||
@param x the value to filter |
|
||||||
@return filtered signal |
|
||||||
*/ |
|
||||||
// timing :8us
|
|
||||||
inline |
|
||||||
int next(int x) |
|
||||||
{ |
|
||||||
acc += ((long)(x-prev_x)<<16)>>1; |
|
||||||
prev_x = x; |
|
||||||
acc -= (long)A*prev_y; // acc has y[n] in upper 17 bits and -e[n] in lower 15 bits
|
|
||||||
prev_y = (acc>>16)<<1; // faster than >>15 but loses bit 0
|
|
||||||
if (acc & 32784) prev_y += 1; // adds 1 if it was in the 0 bit position lost in the shifts above
|
|
||||||
return prev_y; |
|
||||||
} |
|
||||||
|
|
||||||
private: |
|
||||||
long acc; |
|
||||||
int prev_x, prev_y,A; |
|
||||||
}; |
|
||||||
|
|
||||||
/**
|
|
||||||
@example 05.Control_Filters/DCFilter/DCFilter.ino |
|
||||||
This example demonstrates the DCFilter class. |
|
||||||
*/ |
|
||||||
|
|
||||||
#endif // #ifndef DCFILTER_H
|
|
||||||
@ -1,44 +0,0 @@ |
|||||||
/*
|
|
||||||
============================================================================== |
|
||||||
This file is part of Tal-NoiseMaker by Patrick Kunz. |
|
||||||
|
|
||||||
Copyright(c) 2005-2010 Patrick Kunz, TAL |
|
||||||
Togu Audio Line, Inc. |
|
||||||
http://kunz.corrupt.ch
|
|
||||||
|
|
||||||
This file may be licensed under the terms of of the |
|
||||||
GNU General Public License Version 2 (the ``GPL''). |
|
||||||
|
|
||||||
Software distributed under the License is distributed |
|
||||||
on an ``AS IS'' basis, WITHOUT WARRANTY OF ANY KIND, either |
|
||||||
express or implied. See the GPL for the specific language |
|
||||||
governing rights and limitations. |
|
||||||
|
|
||||||
You should have received a copy of the GPL along with this |
|
||||||
program. If not, go to http://www.gnu.org/licenses/gpl.html
|
|
||||||
or write to the Free Software Foundation, Inc., |
|
||||||
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
|
||||||
============================================================================== |
|
||||||
*/ |
|
||||||
|
|
||||||
#if !defined(__OnePoleLP_h) |
|
||||||
#define __OnePoleLP_h |
|
||||||
|
|
||||||
class OnePoleLP { |
|
||||||
public: |
|
||||||
float inputs, outputs, lastOutput; |
|
||||||
|
|
||||||
OnePoleLP() { |
|
||||||
lastOutput = inputs = outputs = 0.0f; |
|
||||||
} |
|
||||||
|
|
||||||
~OnePoleLP() {} |
|
||||||
|
|
||||||
void tick(float *sample, float cutoff) { |
|
||||||
float p = (cutoff * 0.98f) * (cutoff * 0.98f) * (cutoff * 0.98f) * (cutoff * 0.98f); |
|
||||||
outputs = (1.0f - p) * (*sample) + p * outputs; |
|
||||||
*sample = outputs; |
|
||||||
} |
|
||||||
}; |
|
||||||
|
|
||||||
#endif |
|
||||||
Loading…
Reference in new issue