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+/*
+ * Copyright (c) 2008 MUSIC TECHNOLOGY GROUP (MTG)
+ * UNIVERSITAT POMPEU FABRA
+ *
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+/*! \file filters.c
+ * \brief various filters
+ */
+
+#include "sms.h"
+
+/*! \brief coefficient for pre_emphasis filter */
+#define SMS_EMPH_COEF .9
+
+/* pre-emphasis filter function, it returns the filtered value
+ *
+ * sfloat fInput; sound sample
+ */
+sfloat sms_preEmphasis (sfloat fInput, SMS_AnalParams *pAnalParams)
+{
+ sfloat fOutput = 0;
+ fOutput = fInput - SMS_EMPH_COEF * pAnalParams->preEmphasisLastValue;
+ pAnalParams->preEmphasisLastValue = fOutput;
+
+ return (fOutput);
+}
+
+/* de-emphasis filter function, it returns the filtered value
+ *
+ * sfloat fInput; sound input
+ */
+sfloat sms_deEmphasis(sfloat fInput, SMS_SynthParams *pSynthParams)
+{
+ sfloat fOutput = 0;
+ fOutput = fInput + SMS_EMPH_COEF * pSynthParams->deemphasisLastValue;
+ pSynthParams->deemphasisLastValue = fInput;
+
+ return(fOutput);
+}
+
+/*! \brief function to implement a zero-pole filter
+ *
+ * \todo will forgetting to reset pD to zero at the beginning of a new analysis
+ * (when there are multiple analyses within the life of one program)
+ * cause problems?
+ *
+ * \param pFa pointer to numerator coefficients
+ * \param pFb pointer to denominator coefficients
+ * \param nCoeff number of coefficients
+ * \param fInput input sample
+ * \return value is the filtered sample
+ */
+static sfloat ZeroPoleFilter (float *pFa, sfloat *pFb, int nCoeff, sfloat fInput )
+{
+ double fOut = 0;
+ int iSection;
+
+/* static sfloat *pD = NULL; */
+/* if (pD == NULL) */
+/* pD = (sfloat *) calloc(5, sizeof(float)); */
+ static sfloat pD[5] = {0, 0, 0, 0, 0};
+
+ pD[0] = fInput;
+ for (iSection = nCoeff-1; iSection > 0; iSection--)
+ {
+ fOut = fOut + pFa[iSection] * pD[iSection];
+ pD[0] = pD[0] - pFb[iSection] * pD[iSection];
+ pD[iSection] = pD [iSection-1];
+ }
+ fOut = fOut + pFa[0] * pD[0];
+ return((sfloat) fOut);
+}
+
+ /* cutoff 1500 Hz */
+/* static sfloat pFCoeff32k[10] = {0.679459, -2.71784, 4.07676, -2.71784,
+ 0.679459, 1, -3.23168, 3.97664, -2.20137, 0.461665};
+ static sfloat pFCoeff36k[10] = {0.709489, -2.83796, 4.25694, -2.83796,
+ 0.709489, 1, -3.31681, 4.17425, -2.3574, 0.503375};
+ static sfloat pFCoeff40k[10] = {0.734408, -2.93763, 4.40645, -2.93763,
+ 0.734408, 1, -3.38497, 4.33706, -2.48914, 0.539355};
+ static sfloat pFCoeff441k[10] = {0.755893, -3.02357, 4.53536, -3.02357,
+ 0.755893, 1, -3.44205, 4.47657, -2.6043, 0.571374};
+ static sfloat pFCoeff48k[10] = {0.773347, -3.09339, 4.64008, -3.09339,
+ 0.773347, 1, -3.48731, 4.58929, -2.69888, 0.598065};
+*/
+
+
+/*! \brief function to filter a waveform with a high-pass filter
+ *
+ * cutoff =1500 Hz
+ *
+ * \todo this filter only works on sample rates up to 48k?
+ *
+ * \param sizeResidual size of signal
+ * \param pResidual pointer to residual signal
+ * \param iSamplingRate sampling rate of signal
+ */
+void sms_filterHighPass ( int sizeResidual, sfloat *pResidual, int iSamplingRate)
+{
+
+
+ /* cutoff 800Hz */
+ static sfloat pFCoeff32k[10] = {0.814255, -3.25702, 4.88553, -3.25702,
+ 0.814255, 1, -3.58973, 4.85128, -2.92405, 0.66301};
+ static sfloat pFCoeff36k[10] = {0.833098, -3.33239, 4.99859, -3.33239,
+ 0.833098, 1, -3.63528, 4.97089, -3.02934,0.694052};
+ static sfloat pFCoeff40k[10] = {0.848475, -3.3939, 5.09085, -3.3939,
+ 0.848475, 1, -3.67173, 5.068, -3.11597, 0.71991};
+ static sfloat pFCoeff441k[10] = {0.861554, -3.44622, 5.16932, -3.44622,
+ 0.861554, 1, -3.70223, 5.15023, -3.19013, 0.742275};
+ static sfloat pFCoeff48k[10] = {0.872061, -3.48824, 5.23236, -3.48824,
+ 0.872061, 1, -3.72641, 5.21605, -3.25002, 0.76049};
+ sfloat *pFCoeff, fSample = 0;
+ int i;
+
+ if (iSamplingRate <= 32000)
+ pFCoeff = pFCoeff32k;
+ else if (iSamplingRate <= 36000)
+ pFCoeff = pFCoeff36k;
+ else if (iSamplingRate <= 40000)
+ pFCoeff = pFCoeff40k;
+ else if (iSamplingRate <= 44100)
+ pFCoeff = pFCoeff441k;
+ else
+ pFCoeff = pFCoeff48k;
+
+ for(i = 0; i < sizeResidual; i++)
+ {
+ /* try to avoid underflow when there is nothing to filter */
+ if (i > 0 && fSample == 0 && pResidual[i] == 0)
+ return;
+
+ fSample = pResidual[i];
+ pResidual[i] =
+ ZeroPoleFilter (&pFCoeff[0], &pFCoeff[5], 5, fSample);
+ }
+}
+
+/*! \brief a spectral filter
+ *
+ * filter each point of the current array by the surounding
+ * points using a triangular window
+ *
+ * \param pFArray two dimensional input array
+ * \param size1 vertical size of pFArray
+ * \param size2 horizontal size of pFArray
+ * \param pFOutArray output array of size size1
+ */
+void sms_filterArray (sfloat *pFArray, int size1, int size2, sfloat *pFOutArray)
+{
+ int i, j, iPoint, iFrame, size2_2 = size2-2, size2_1 = size2-1;
+ sfloat *pFCurrentArray = pFArray + (size2_1) * size1;
+ sfloat fVal, fWeighting, fTotalWeighting, fTmpVal;
+
+ /* find the filtered envelope */
+ for (i = 0; i < size1; i++)
+ {
+ fVal = pFCurrentArray[i];
+ fTotalWeighting = 1;
+ /* filter by the surrounding points */
+ for (j = 1; j < (size2_2); j++)
+ {
+ fWeighting = (sfloat) size2 / (1+ j);
+ /* filter on the vertical dimension */
+ /* consider the lower points */
+ iPoint = i - (size2_1) + j;
+ if (iPoint >= 0)
+ {
+ fVal += pFCurrentArray[iPoint] * fWeighting;
+ fTotalWeighting += fWeighting;
+ }
+ /* consider the higher points */
+ iPoint = i + (size2_1) - j;
+ if (iPoint < size1)
+ {
+ fVal += pFCurrentArray[iPoint] * fWeighting;
+ fTotalWeighting += fWeighting;
+ }
+ /*filter on the horizontal dimension */
+ /* consider the previous points */
+ iFrame = j;
+ fTmpVal = pFArray[iFrame*size1 + i];
+ if (fTmpVal)
+ {
+ fVal += fTmpVal * fWeighting;
+ fTotalWeighting += fWeighting;
+ }
+ }
+ /* scale value by weighting */
+ pFOutArray[i] = fVal / fTotalWeighting;
+ }
+}
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