Andreas Pflug wrote:
Albert Santoni wrote:
Hey Andreas,
Just a quick note - I think this is really cool, but I don't think I
know enough about the existing EQ code yet to comment. I've forwarded
your email to John Sully and Ben Wheeler and asked them for thoughts.
The functions replace _processXXXpass (the c version always, the as
version if the calling conventions match; If the loop around
_processXXXpass is done in assember too, it's probably be less sensitive)
Um, I just realized this information isn't complete. My functions take a
float array as coef param, while libfir will deliver a double array, so
the fi_design_coef result needs a deep copy to a float array. Attached
the enginefilterbutterworth.cpp I'm using (filterstuff.h has just the
prototypes).
Regards,
Andreas
/***************************************************************************
* enginefilter.cpp - Wrapper for FidLib Filter Library *
* ---------------------- *
* copyright : (C) 2007 by John Sully *
* email : [email protected] *
* *
**************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#include "enginefilterbutterworth8.h"
#include "enginefilter.h"
#include "engineobject.h"
#include "../lib/fidlib-0.9.9/fidlib.h"
extern "C"
{
#include "filterstuff.h"
}
inline double zap_denormal2(CSAMPLE x)
{
// fabs too slow on Windows...
CSAMPLE absx;
if (x<0)
absx = -x;
else
absx = x;
return (absx > 1e-15f && absx < 1e15f) ? x : 0.f;
}
inline void zap_buffer_denormals2(CSAMPLE *buf, int bufSize)
{
for(int i=0; i < bufSize; i++)
buf[i] = zap_denormal2(buf[i]);
}
#define FILTERORDER 4
EngineFilterButterworth8::EngineFilterButterworth8(filterType type, int sampleRate, double freqCorner1, double freqCorner2)
{
m_type = type;
double m_coef[MAX_COEFS];
switch(type)
{
case FILTER_LOWPASS:
m_bufSize = FILTERORDER*2;
Q_ASSERT(freqCorner2 == 0);
m_coef[0] = 1 * fid_design_coef(m_coef + 1, m_bufSize, "LpBu8", sampleRate, freqCorner1, 0, 0);
break;
case FILTER_BANDPASS:
m_bufSize = FILTERORDER*4;
m_coef[0]= 1 * fid_design_coef(m_coef + 1, m_bufSize, "BpBu8", sampleRate, freqCorner1, freqCorner2, 0);
break;
case FILTER_HIGHPASS:
m_bufSize = FILTERORDER*2;
Q_ASSERT(freqCorner2 == 0);
m_coef[0] = 1 * fid_design_coef(m_coef + 1, m_bufSize, "HpBu8", sampleRate, freqCorner1, 0, 0);
break;
}
memset(buf1, 0, sizeof(CSAMPLE)*m_bufSize);
memset(buf2, 0, sizeof(CSAMPLE)*m_bufSize);
for (int i=0 ; i <= m_bufSize ; i++)
coef[i] = (CSAMPLE)m_coef[i];
}
EngineFilterButterworth8::~EngineFilterButterworth8()
{
}
void EngineFilterButterworth8::process(const CSAMPLE *pIn, const CSAMPLE *ppOut, const int iBufferSize)
{
CSAMPLE * pOutput = (CSAMPLE *)ppOut;
switch(m_type)
{
case FILTER_LOWPASS:
for(int i=0; i < iBufferSize; i += 2)
{
pOutput[i] = doLowpass(coef, buf1, pIn[i]);
pOutput[i+1] = doLowpass(coef, buf2, pIn[i+1]);
}
break;
case FILTER_BANDPASS:
for(int i=0; i < iBufferSize; i += 2)
{
pOutput[i] = doBandpass(coef, buf1, pIn[i]);
pOutput[i+1] = doBandpass(coef, buf2, pIn[i+1]);
if(pOutput[i] != pOutput[i]) //Check for NaN
pOutput[i] = 0;
if(pOutput[i+1] != pOutput[i+1]) //Check for NaN
pOutput[i+1] = 0;
}
break;
case FILTER_HIGHPASS:
for(int i=0; i < iBufferSize; i += 2)
{
pOutput[i] = doHighpass(coef, buf1, pIn[i]);
pOutput[i+1] = doHighpass(coef, buf2, pIn[i+1]);
}
break;
}
zap_buffer_denormals2(buf1, m_bufSize);
zap_buffer_denormals2(buf2, m_bufSize);
}
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