1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
| #include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
typedef struct ID3v2_s {
char ID3[3];
char version[2];
char flag[1];
char size[4];
int valid;
} ID3v2;
typedef struct frame_s {
char ID[4];
char size[4];
char flag[2];
} FRAME;
static long array2long(char array[4]) {
long size = 0;
size_t i;
for(i = 0; i < 4; ++i) {
size *= 0x80;
size += (int)(array[i]%0x80);
}
return size;
}
static ID3v2 read_header(const char* filename) {
ID3v2 ret = {"", "", "", "", 0};
FILE *f = fopen(filename, "rb");
if(NULL != f) {
/* Lecture du header principal */
fread(ret.ID3, 1, sizeof ret.ID3, f);
fread(ret.version, 1, sizeof ret.version, f);
fread(ret.flag, 1, sizeof ret.flag, f);
fread(ret.size, 1, sizeof ret.size, f);
/* Le tag est-il valide ?*/
if(0 == strncmp(ret.ID3, "ID3", 3)) {
long size = 0;
FRAME frame;
ret.valid = 1;
/* on tente de lire chaque frame */
while( 1 == fread(&frame, sizeof frame, 1, f) ) {
size = array2long(frame.size);
/* frame vide ? on sort */
if((0 == size)||(0==strncmp(frame.ID, "\0\0\0\0", 4))) {
break;
}
/* affichage du type de frame */
printf("frame %c%c%c%c found\n", frame.ID[0], frame.ID[1],
frame.ID[2], frame.ID[3]);
/* Comme on a lu les specif, on sait que TALB, c'est le
titre du morceau*/
if(0 == strncmp(frame.ID, "TALB", 4)) {
long i;
printf("titre : ");
for(i = 0; i < size; ++i) {
putchar(fgetc(f));
}
putchar('\n');
/* la frame a été lue, on passe à la suivante */
continue;
}
/* on passe le reste de la frame */
fseek(f, size, SEEK_CUR);
}
}
fclose(f);
} else {
perror(filename);
}
return ret;
}
int main(int argc, char *argv[])
{
if(2 == argc) {
ID3v2 tag = read_header(argv[1]);
if(tag.valid) {
printf("tag : %s\n", tag.ID3);
printf("version : 0x%02x%02x\n", tag.version[0], tag.version[1]);
printf("size : 0x%02x%02x%02x%02x\n",tag.size[0], tag.size[1],
tag.size[2], tag.size[3]);
}
} else {
fprintf(stderr, "usage : %s file.mp3\n", *argv);
}
return EXIT_SUCCESS;
} |
