/* libSoX Compander Transfer Function: (c) 2007 robs@users.sourceforge.net * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or (at * your option) any later version. * * This library 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 Lesser * General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this library; if not, write to the Free Software Foundation, * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA */ #include "sox_i.h" #include "compandt.h"#include <string.h> #define LOG_TO_LOG10(x) ((x) * 20 / M_LN10) sox_bool lsx_compandt_show(sox_compandt_t * t, sox_plot_t plot){  int i;   for (i = 1; t->segments[i-1].x; ++i)    lsx_debug("TF: %g %g %g %g",       LOG_TO_LOG10(t->segments[i].x),       LOG_TO_LOG10(t->segments[i].y),       LOG_TO_LOG10(t->segments[i].a),       LOG_TO_LOG10(t->segments[i].b));   if (plot == sox_plot_octave) {    printf(      "%% GNU Octave file (may also work with MATLAB(R) )\n"      "in=linspace(-99.5,0,200);\n"      "out=[");    for (i = -199; i <= 0; ++i) {      double in = i/2.;      double in_lin = pow(10., in/20);      printf("%g ", in + 20 * log10(lsx_compandt(t, in_lin)));    }    printf(      "];\n"      "plot(in,out)\n"      "title('SoX effect: compand')\n"      "xlabel('Input level (dB)')\n"      "ylabel('Output level (dB)')\n"      "grid on\n"      "disp('Hit return to continue')\n"      "pause\n");    return sox_false;  }  if (plot == sox_plot_gnuplot) {    printf(      "# gnuplot file\n"      "set title 'SoX effect: compand'\n"      "set xlabel 'Input level (dB)'\n"      "set ylabel 'Output level (dB)'\n"      "set grid xtics ytics\n"      "set key off\n"      "plot '-' with lines\n");    for (i = -199; i <= 0; ++i) {      double in = i/2.;      double in_lin = pow(10., in/20);      printf("%g %g\n", in, in + 20 * log10(lsx_compandt(t, in_lin)));    }    printf(      "e\n"      "pause -1 'Hit return to continue'\n");    return sox_false;  }  return sox_true;} static void prepare_transfer_fn(sox_compandt_t * t){  int i;  double radius = t->curve_dB * M_LN10 / 20;   for (i = 0; !i || t->segments[i-2].x; i += 2) {    t->segments[i].y += t->outgain_dB;    t->segments[i].x *= M_LN10 / 20; /* Convert to natural logs */    t->segments[i].y *= M_LN10 / 20;  } #define line1 t->segments[i - 4]#define curve t->segments[i - 3]#define line2 t->segments[i - 2]#define line3 t->segments[i - 0]  for (i = 4; t->segments[i - 2].x; i += 2) {    double x, y, cx, cy, in1, in2, out1, out2, theta, len, r;     line1.a = 0;    line1.b = (line2.y - line1.y) / (line2.x - line1.x);     line2.a = 0;    line2.b = (line3.y - line2.y) / (line3.x - line2.x);     theta = atan2(line2.y - line1.y, line2.x - line1.x);    len = sqrt(pow(line2.x - line1.x, 2.) + pow(line2.y - line1.y, 2.));    r = min(radius, len);    curve.x = line2.x - r * cos(theta);    curve.y = line2.y - r * sin(theta);     theta = atan2(line3.y - line2.y, line3.x - line2.x);    len = sqrt(pow(line3.x - line2.x, 2.) + pow(line3.y - line2.y, 2.));    r = min(radius, len / 2);    x = line2.x + r * cos(theta);    y = line2.y + r * sin(theta);     cx = (curve.x + line2.x + x) / 3;    cy = (curve.y + line2.y + y) / 3;     line2.x = x;    line2.y = y;     in1 = cx - curve.x;    out1 = cy - curve.y;    in2 = line2.x - curve.x;    out2 = line2.y - curve.y;    curve.a = (out2/in2 - out1/in1) / (in2-in1);    curve.b = out1/in1 - curve.a*in1;  }#undef line1#undef curve#undef line2#undef line3  t->segments[i - 3].x = 0;  t->segments[i - 3].y = t->segments[i - 2].y;   t->in_min_lin = exp(t->segments[1].x);  t->out_min_lin= exp(t->segments[1].y);} static sox_bool parse_transfer_value(char const * text, double * value){  char dummy;     /* To check for extraneous chars. */   if (!text) {    lsx_fail("syntax error trying to read transfer function value");    return sox_false;  }  if (!strcmp(text, "-inf"))    *value = -20 * log10(-(double)SOX_SAMPLE_MIN);  else if (sscanf(text, "%lf %c", value, &dummy) != 1) {    lsx_fail("syntax error trying to read transfer function value");    return sox_false;  }  else if (*value > 0) {    lsx_fail("transfer function values are relative to maximum volume so can't exceed 0dB");    return sox_false;  }  return sox_true;} sox_bool lsx_compandt_parse(sox_compandt_t * t, char * points, char * gain){  char const * text = points;  unsigned i, j, num, pairs, commas = 0;  char dummy;     /* To check for extraneous chars. */   if (sscanf(points, "%lf %c", &t->curve_dB, &dummy) == 2 && dummy == ':')    points = strchr(points, ':') + 1;  else t->curve_dB = 0;  t->curve_dB = max(t->curve_dB, .01);   while (*text) commas += *text++ == ',';  pairs = 1 + commas / 2;  ++pairs;    /* allow room for extra pair at the beginning */  pairs *= 2; /* allow room for the auto-curves */  ++pairs;    /* allow room for 0,0 at end */  t->segments = lsx_calloc(pairs, sizeof(*t->segments)); #define s(n) t->segments[2*((n)+1)]  for (i = 0, text = strtok(points, ","); text != NULL; ++i) {    if (!parse_transfer_value(text, &s(i).x))      return sox_false;    if (i && s(i-1).x > s(i).x) {      lsx_fail("transfer function input values must be strictly increasing");      return sox_false;    }    if (i || (commas & 1)) {      text = strtok(NULL, ",");      if (!parse_transfer_value(text, &s(i).y))        return sox_false;      s(i).y -= s(i).x;    }    text = strtok(NULL, ",");  }  num = i;   if (num == 0 || s(num-1).x) /* Add 0,0 if necessary */    ++num;#undef s   if (gain && sscanf(gain, "%lf %c", &t->outgain_dB, &dummy) != 1) {    lsx_fail("syntax error trying to read post-processing gain value");    return sox_false;  } #define s(n) t->segments[2*(n)]  s(0).x = s(1).x - 2 * t->curve_dB; /* Add a tail off segment at the start */  s(0).y = s(1).y;  ++num;   for (i = 2; i < num; ++i) { /* Join adjacent colinear segments */    double g1 = (s(i-1).y - s(i-2).y) * (s(i-0).x - s(i-1).x);    double g2 = (s(i-0).y - s(i-1).y) * (s(i-1).x - s(i-2).x);    if (fabs(g1 - g2)) /* fabs stops epsilon problems */      continue;    --num;    for (j = --i; j < num; ++j)      s(j) = s(j+1);  }#undef s   prepare_transfer_fn(t);  return sox_true;} void lsx_compandt_kill(sox_compandt_t * p){  free(p->segments);}