2010-01-01 05:09:30 +00:00
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/*
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* $Id$
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*
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* ***** BEGIN LGPL LICENSE BLOCK *****
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*
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* Copyright 2009 Jörg Hermann Müller
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*
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* This file is part of AudaSpace.
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*
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* AudaSpace is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* AudaSpace is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with AudaSpace. If not, see <http://www.gnu.org/licenses/>.
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*
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* ***** END LGPL LICENSE BLOCK *****
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*/
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#include "AUD_LowpassReader.h"
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#include "AUD_Buffer.h"
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#include <cstring>
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#include <cmath>
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2010-01-01 11:40:48 +00:00
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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2010-01-01 05:09:30 +00:00
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#define CC channels + channel
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AUD_LowpassReader::AUD_LowpassReader(AUD_IReader* reader, float frequency,
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float Q) :
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AUD_EffectReader(reader)
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{
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AUD_Specs specs = reader->getSpecs();
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int samplesize = AUD_SAMPLE_SIZE(specs);
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m_buffer = new AUD_Buffer(); AUD_NEW("buffer")
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m_outvalues = new AUD_Buffer(samplesize * AUD_LOWPASS_ORDER);
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AUD_NEW("buffer")
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memset(m_outvalues->getBuffer(), 0, samplesize * AUD_LOWPASS_ORDER);
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m_invalues = new AUD_Buffer(samplesize * AUD_LOWPASS_ORDER);
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AUD_NEW("buffer")
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memset(m_invalues->getBuffer(), 0, samplesize * AUD_LOWPASS_ORDER);
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m_position = 0;
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// calculate coefficients
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2010-01-01 11:55:56 +00:00
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float w0 = 2 * M_PI * frequency / specs.rate;
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2010-01-01 05:09:30 +00:00
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float alpha = sin(w0) / (2 * Q);
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float norm = 1 + alpha;
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m_coeff[0][0] = 0;
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m_coeff[0][1] = -2 * cos(w0) / norm;
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m_coeff[0][2] = (1 - alpha) / norm;
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m_coeff[1][2] = m_coeff[1][0] = (1 - cos(w0)) / (2 * norm);
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m_coeff[1][1] = (1 - cos(w0)) / norm;
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}
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AUD_LowpassReader::~AUD_LowpassReader()
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{
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delete m_buffer; AUD_DELETE("buffer")
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delete m_outvalues; AUD_DELETE("buffer")
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delete m_invalues; AUD_DELETE("buffer");
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}
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void AUD_LowpassReader::read(int & length, sample_t* & buffer)
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{
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sample_t* buf;
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sample_t* outvalues;
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sample_t* invalues;
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outvalues = m_outvalues->getBuffer();
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invalues = m_invalues->getBuffer();
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AUD_Specs specs = m_reader->getSpecs();
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m_reader->read(length, buf);
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if(m_buffer->getSize() < length * AUD_SAMPLE_SIZE(specs))
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m_buffer->resize(length * AUD_SAMPLE_SIZE(specs));
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buffer = m_buffer->getBuffer();
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int channels = specs.channels;
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for(int channel = 0; channel < channels; channel++)
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{
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for(int i = 0; i < length; i++)
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{
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invalues[m_position * CC] = buf[i * CC];
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outvalues[m_position * CC] = 0;
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for(int j = 0; j < AUD_LOWPASS_ORDER; j++)
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{
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outvalues[m_position * CC] += m_coeff[1][j] *
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invalues[((m_position + j) % AUD_LOWPASS_ORDER) * CC] -
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m_coeff[0][j] *
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outvalues[((m_position + j) % AUD_LOWPASS_ORDER) * CC];
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}
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buffer[i * CC] = outvalues[m_position * CC];
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m_position = (m_position + AUD_LOWPASS_ORDER-1) % AUD_LOWPASS_ORDER;
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}
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}
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}
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