1 /* Simple example of using SoX libraries
2 *
3 * Copyright (c) 2008 robs@users.sourceforge.net
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the
7 * Free Software Foundation; either version 2 of the License, or (at your
8 * option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
13 * Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20 #ifdef NDEBUG /* N.B. assert used with active statements so enable always. */
21 #undef NDEBUG /* Must undef above assert.h or other that might include it. */
22 #endif
23
24 #include "sox.h"
25 #include "util.h"
26 #include <stdio.h>
27 #include <math.h>
28 #include <assert.h>
29
30 /*
31 * Reads input file and displays a few seconds of wave-form, starting from
32 * a given time through the audio. E.g. example2 song2.au 30.75 1
33 */
main(int argc,char * argv[])34 int main(int argc, char * argv[])
35 {
36 sox_format_t * in;
37 sox_sample_t * buf;
38 size_t blocks, block_size;
39 /* Period of audio over which we will measure its volume in order to
40 * display the wave-form: */
41 static const double block_period = 0.025; /* seconds */
42 double start_secs = 0, period = 2;
43 char dummy;
44 uint64_t seek;
45
46 /* All libSoX applications must start by initialising the SoX library */
47 assert(sox_init() == SOX_SUCCESS);
48
49 assert(argc > 1);
50 ++argv, --argc; /* Move to 1st parameter */
51
52 /* Open the input file (with default parameters) */
53 assert((in = sox_open_read(*argv, NULL, NULL, NULL)));
54 ++argv, --argc; /* Move past this parameter */
55
56 if (argc) { /* If given, read the start time: */
57 assert(sscanf(*argv, "%lf%c", &start_secs, &dummy) == 1);
58 ++argv, --argc; /* Move past this parameter */
59 }
60
61 if (argc) { /* If given, read the period of time to display: */
62 assert(sscanf(*argv, "%lf%c", &period, &dummy) == 1);
63 ++argv, --argc; /* Move past this parameter */
64 }
65
66 /* Calculate the start position in number of samples: */
67 seek = start_secs * in->signal.rate * in->signal.channels + .5;
68 /* Make sure that this is at a `wide sample' boundary: */
69 seek -= seek % in->signal.channels;
70 /* Move the file pointer to the desired starting position */
71 assert(sox_seek(in, seek, SOX_SEEK_SET) == SOX_SUCCESS);
72
73 /* Convert block size (in seconds) to a number of samples: */
74 block_size = block_period * in->signal.rate * in->signal.channels + .5;
75 /* Make sure that this is at a `wide sample' boundary: */
76 block_size -= block_size % in->signal.channels;
77 /* Allocate a block of memory to store the block of audio samples: */
78 assert((buf = malloc(sizeof(sox_sample_t) * block_size)));
79
80 /* This example program requires that the audio has precisely 2 channels: */
81 assert(in->signal.channels == 2);
82
83 /* Read and process blocks of audio for the selected period or until EOF: */
84 for (blocks = 0; sox_read(in, buf, block_size) == block_size && blocks * block_period < period; ++blocks) {
85 double left = 0, right = 0;
86 size_t i;
87 static const char line[] = "===================================";
88 int l, r;
89
90 for (i = 0; i < block_size; ++i) {
91 SOX_SAMPLE_LOCALS;
92 /* convert the sample from SoX's internal format to a `double' for
93 * processing in this application: */
94 double sample = SOX_SAMPLE_TO_FLOAT_64BIT(buf[i],);
95
96 /* The samples for each channel are interleaved; in this example
97 * we allow only stereo audio, so the left channel audio can be found in
98 * even-numbered samples, and the right channel audio in odd-numbered
99 * samples: */
100 if (i & 1)
101 right = max(right, fabs(sample)); /* Find the peak volume in the block */
102 else
103 left = max(left, fabs(sample)); /* Find the peak volume in the block */
104 }
105
106 /* Build up the wave form by displaying the left & right channel
107 * volume as a line length: */
108 l = (1 - left) * 35 + .5;
109 r = (1 - right) * 35 + .5;
110 printf("%8.3f%36s|%s\n", start_secs + blocks * block_period, line + l, line + r);
111 }
112
113 /* All done; tidy up: */
114 free(buf);
115 sox_close(in);
116 sox_quit();
117 return 0;
118 }
119