/*
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
 #include <inttypes.h>
 
 #define FFMIN(a,b) ((a) > (b) ? (b) : (a))
 #define FFMAX(a,b) ((a) > (b) ? (a) : (b))
 

 static int64_t fsize(FILE *f) {
     int64_t end, pos = ftell(f);

     fseek(f, 0, SEEK_END);
     end = ftell(f);
     fseek(f, pos, SEEK_SET);
     return end;
 }
 

 int main(int argc, char **argv) {

     FILE *f[2];
     int i, pos;
     int siglen, datlen;

     int bestpos = 0;

     double bestc = 0;
     double sigamp = 0;

     int16_t *signal, *data;

     int maxshift = 16384;

 
     if (argc < 3) {
         printf("audiomatch <testfile> <reffile>\n");
         printf("WAV headers are skipped automatically.\n");
         return 1;
     }
 
     f[0] = fopen(argv[1], "rb");
     f[1] = fopen(argv[2], "rb");
     if (!f[0] || !f[1]) {
         fprintf(stderr, "Could not open input files.\n");
         return 1;
     }
 
     for (i = 0; i < 2; i++) {
         uint8_t p[100];
         if (fread(p, 1, 12, f[i]) != 12)
             return 1;
         if (!memcmp(p, "RIFF", 4) &&
             !memcmp(p + 8, "WAVE", 4)) {
             if (fread(p, 1, 8, f[i]) != 8)
                 return 1;
             while (memcmp(p, "data", 4)) {
                 int s = p[4] | p[5] << 8 | p[6] << 16 | p[7] << 24;
                 fseek(f[i], s, SEEK_CUR);
                 if (fread(p, 1, 8, f[i]) != 8)
                     return 1;
             }
         } else {
             fseek(f[i], -12, SEEK_CUR);
         }
     }
 
     datlen = fsize(f[0]) - ftell(f[0]);
     siglen = fsize(f[1]) - ftell(f[1]);
     data   = malloc(datlen * sizeof(*data));
     signal = malloc(siglen * sizeof(*signal));
 

     if (fread(data  , 1, datlen, f[0]) != datlen)
         return 1;
     if (fread(signal, 1, siglen, f[1]) != siglen)
         return 1;

     datlen /= 2;
     siglen /= 2;
 

     for (i = 0; i < siglen; i++) {

         signal[i] = ((uint8_t*)(signal + i))[0] + 256*((uint8_t*)(signal + i))[1];
         sigamp += signal[i] * signal[i];
     }

     for (i = 0; i < datlen; i++)

         data[i] = ((uint8_t*)(data + i))[0] + 256*((uint8_t*)(data + i))[1];
 

     for (pos = 0; pos < maxshift; pos = pos < 0 ? -pos: -pos-1) {
         int64_t c = 0;

         int testlen = FFMIN(siglen, datlen-pos);

         for (i = FFMAX(0, -pos); i < testlen; i++) {
             int j = pos + i;

             c += signal[i] * data[j];
         }

         if (fabs(c) > sigamp * 0.94)

             maxshift = FFMIN(maxshift, fabs(pos)+32);

         if (fabs(c) > fabs(bestc)) {
             bestc = c;

             bestpos = pos;
         }
     }

     printf("presig: %d postsig:%d c:%7.4f lenerr:%d\n", bestpos, datlen - siglen - bestpos, bestc / sigamp, datlen - siglen);

 
     return 0;

 }