1 /*
2 ** Copyright (C) 2001-2013 Erik de Castro Lopo <erikd@mega-nerd.com>
3 **
4 ** All rights reserved.
5 **
6 ** Redistribution and use in source and binary forms, with or without
7 ** modification, are permitted provided that the following conditions are
8 ** met:
9 **
10 ** * Redistributions of source code must retain the above copyright
11 ** notice, this list of conditions and the following disclaimer.
12 ** * Redistributions in binary form must reproduce the above copyright
13 ** notice, this list of conditions and the following disclaimer in
14 ** the documentation and/or other materials provided with the
15 ** distribution.
16 ** * Neither the author nor the names of any contributors may be used
17 ** to endorse or promote products derived from this software without
18 ** specific prior written permission.
19 **
20 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 ** TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 ** PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
24 ** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25 ** EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
26 ** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
27 ** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
28 ** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
29 ** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
30 ** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #include <stdio.h>
34 #include <string.h>
35
36 /* Include this header file to use functions from libsndfile. */
37 #include <sndfile.h>
38
39 /* This will be the length of the buffer used to hold.frames while
40 ** we process them.
41 */
42 #define BUFFER_LEN 1024
43
44 /* libsndfile can handle more than 6 channels but we'll restrict it to 6. */
45 #define MAX_CHANNELS 6
46
47 /* Function prototype. */
48 static void process_data (double *data, int count, int channels) ;
49
50
51 int
main(void)52 main (void)
53 { /* This is a buffer of double precision floating point values
54 ** which will hold our data while we process it.
55 */
56 static double data [BUFFER_LEN] ;
57
58 /* A SNDFILE is very much like a FILE in the Standard C library. The
59 ** sf_open function return an SNDFILE* pointer when they sucessfully
60 ** open the specified file.
61 */
62 SNDFILE *infile, *outfile ;
63
64 /* A pointer to an SF_INFO struct is passed to sf_open.
65 ** On read, the library fills this struct with information about the file.
66 ** On write, the struct must be filled in before calling sf_open.
67 */
68 SF_INFO sfinfo ;
69 int readcount ;
70 const char *infilename = "input.wav" ;
71 const char *outfilename = "output.wav" ;
72
73 /* The SF_INFO struct must be initialized before using it.
74 */
75 memset (&sfinfo, 0, sizeof (sfinfo)) ;
76
77 /* Here's where we open the input file. We pass sf_open the file name and
78 ** a pointer to an SF_INFO struct.
79 ** On successful open, sf_open returns a SNDFILE* pointer which is used
80 ** for all subsequent operations on that file.
81 ** If an error occurs during sf_open, the function returns a NULL pointer.
82 **
83 ** If you are trying to open a raw headerless file you will need to set the
84 ** format and channels fields of sfinfo before calling sf_open(). For
85 ** instance to open a raw 16 bit stereo PCM file you would need the following
86 ** two lines:
87 **
88 ** sfinfo.format = SF_FORMAT_RAW | SF_FORMAT_PCM_16 ;
89 ** sfinfo.channels = 2 ;
90 */
91 if (! (infile = sf_open (infilename, SFM_READ, &sfinfo)))
92 { /* Open failed so print an error message. */
93 printf ("Not able to open input file %s.\n", infilename) ;
94 /* Print the error message from libsndfile. */
95 puts (sf_strerror (NULL)) ;
96 return 1 ;
97 } ;
98
99 if (sfinfo.channels > MAX_CHANNELS)
100 { printf ("Not able to process more than %d channels\n", MAX_CHANNELS) ;
101 return 1 ;
102 } ;
103 /* Open the output file. */
104 if (! (outfile = sf_open (outfilename, SFM_WRITE, &sfinfo)))
105 { printf ("Not able to open output file %s.\n", outfilename) ;
106 puts (sf_strerror (NULL)) ;
107 return 1 ;
108 } ;
109
110 /* While there are.frames in the input file, read them, process
111 ** them and write them to the output file.
112 */
113 while ((readcount = sf_read_double (infile, data, BUFFER_LEN)))
114 { process_data (data, readcount, sfinfo.channels) ;
115 sf_write_double (outfile, data, readcount) ;
116 } ;
117
118 /* Close input and output files. */
119 sf_close (infile) ;
120 sf_close (outfile) ;
121
122 return 0 ;
123 } /* main */
124
125 static void
process_data(double * data,int count,int channels)126 process_data (double *data, int count, int channels)
127 { double channel_gain [MAX_CHANNELS] = { 0.5, 0.8, 0.1, 0.4, 0.4, 0.9 } ;
128 int k, chan ;
129
130 /* Process the data here.
131 ** If the soundfile contains more then 1 channel you need to take care of
132 ** the data interleaving youself.
133 ** Current we just apply a channel dependant gain.
134 */
135
136 for (chan = 0 ; chan < channels ; chan ++)
137 for (k = chan ; k < count ; k+= channels)
138 data [k] *= channel_gain [chan] ;
139
140 return ;
141 } /* process_data */
142
143