/* libSoX effect: tremolo  (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" static int getopts(sox_effect_t * effp, int argc, char * * argv){  double speed, depth = 40;  char dummy;     /* To check for extraneous chars. */  char offset[100];  char * args[] = {0, "sine", "fmod", 0, 0, "25"};   if (argc < 2 || argc > 3 ||      sscanf(argv[1], "%lf %c", &speed, &dummy) != 1 || speed < 0 ||      (argc > 2 && sscanf(argv[2], "%lf %c", &depth, &dummy) != 1) ||      depth <= 0 || depth > 100)    return lsx_usage(effp);  args[0] = argv[0];  args[3] = argv[1];  sprintf(offset, "%g", 100 - depth / 2);  args[4] = offset;  return lsx_synth_effect_fn()->getopts(effp, (int)array_length(args), args);} sox_effect_handler_t const * lsx_tremolo_effect_fn(void){  static sox_effect_handler_t handler;  handler = *lsx_synth_effect_fn();  handler.name = "tremolo";  handler.usage = "speed_Hz [depth_percent]";  handler.getopts = getopts;  return &handler;}