/* 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 #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); }