FFmpeg
audiomatch.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <math.h>
23 #include <inttypes.h>
24 
25 #define FFMIN(a,b) ((a) > (b) ? (b) : (a))
26 #define FFMAX(a,b) ((a) > (b) ? (a) : (b))
27 
28 static int64_t fsize(FILE *f) {
29  int64_t end, pos = ftell(f);
30  fseek(f, 0, SEEK_END);
31  end = ftell(f);
32  fseek(f, pos, SEEK_SET);
33  return end;
34 }
35 
36 int main(int argc, char **argv) {
37  FILE *f[2];
38  int i, pos;
39  int siglen, datlen;
40  int bestpos = 0;
41  double bestc = 0;
42  double sigamp = 0;
43  int16_t *signal, *data;
44  int maxshift = 16384;
45 
46  if (argc < 3) {
47  printf("audiomatch <testfile> <reffile>\n");
48  printf("WAV headers are skipped automatically.\n");
49  return 1;
50  }
51 
52  f[0] = fopen(argv[1], "rb");
53  f[1] = fopen(argv[2], "rb");
54  if (!f[0] || !f[1]) {
55  fprintf(stderr, "Could not open input files.\n");
56  return 1;
57  }
58 
59  for (i = 0; i < 2; i++) {
60  uint8_t p[100];
61  if (fread(p, 1, 12, f[i]) != 12)
62  return 1;
63  if (!memcmp(p, "RIFF", 4) &&
64  !memcmp(p + 8, "WAVE", 4)) {
65  if (fread(p, 1, 8, f[i]) != 8)
66  return 1;
67  while (memcmp(p, "data", 4)) {
68  int s = p[4] | p[5] << 8 | p[6] << 16 | p[7] << 24;
69  fseek(f[i], s, SEEK_CUR);
70  if (fread(p, 1, 8, f[i]) != 8)
71  return 1;
72  }
73  } else {
74  fseek(f[i], -12, SEEK_CUR);
75  }
76  }
77 
78  datlen = fsize(f[0]) - ftell(f[0]);
79  siglen = fsize(f[1]) - ftell(f[1]);
80  data = malloc(datlen * sizeof(*data));
81  signal = malloc(siglen * sizeof(*signal));
82 
83  if (fread(data , 1, datlen, f[0]) != datlen)
84  return 1;
85  if (fread(signal, 1, siglen, f[1]) != siglen)
86  return 1;
87  datlen /= 2;
88  siglen /= 2;
89 
90  for (i = 0; i < siglen; i++) {
91  signal[i] = ((uint8_t*)(signal + i))[0] + 256*((uint8_t*)(signal + i))[1];
92  sigamp += signal[i] * signal[i];
93  }
94  for (i = 0; i < datlen; i++)
95  data[i] = ((uint8_t*)(data + i))[0] + 256*((uint8_t*)(data + i))[1];
96 
97  for (pos = 0; pos < maxshift; pos = pos < 0 ? -pos: -pos-1) {
98  int64_t c = 0;
99  int testlen = FFMIN(siglen, datlen-pos);
100  for (i = FFMAX(0, -pos); i < testlen; i++) {
101  int j = pos + i;
102  c += signal[i] * data[j];
103  }
104  if (fabs(c) > sigamp * 0.94)
105  maxshift = FFMIN(maxshift, fabs(pos)+32);
106  if (fabs(c) > fabs(bestc)) {
107  bestc = c;
108  bestpos = pos;
109  }
110  }
111  printf("presig: %d postsig:%d c:%7.4f lenerr:%d\n", bestpos, datlen - siglen - bestpos, bestc / sigamp, datlen - siglen);
112 
113  return 0;
114 }
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
int main(int argc, char **argv)
Definition: audiomatch.c:36
uint8_t
#define f(width, name)
Definition: cbs_vp9.c:255
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
#define FFMIN(a, b)
Definition: audiomatch.c:25
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
#define s(width, name)
Definition: cbs_vp9.c:257
#define FFMAX(a, b)
Definition: audiomatch.c:26
printf("static const uint8_t my_array[100] = {\n")
static int64_t fsize(FILE *f)
Definition: audiomatch.c:28