interpretor/libsndfile-1.0.25/examples/sfprocess.c

   1 /*
   2 ** Copyright (C) 2001-2011 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
  35 /* Include this header file to use functions from libsndfile. */
  36 #include        <sndfile.h>
  37
  38 /*    This will be the length of the buffer used to hold.frames while
  39 **    we process them.
  40 */
  41 #define         BUFFER_LEN      1024
  42
  43 /* libsndfile can handle more than 6 channels but we'll restrict it to 6. */
  44 #define         MAX_CHANNELS    6
  45
  46 /* Function prototype. */
  47 static void process_data (double *data, int count, int channels) ;
  48
  49
  50 int
  51 main (void)
  52 {   /* This is a buffer of double precision floating point values
  53     ** which will hold our data while we process it.
  54     */
  55     static double data [BUFFER_LEN] ;
  56
  57     /* A SNDFILE is very much like a FILE in the Standard C library. The
  58     ** sf_open function return an SNDFILE* pointer when they sucessfully
  59         ** open the specified file.
  60     */
  61     SNDFILE      *infile, *outfile ;
  62
  63     /* A pointer to an SF_INFO stutct is passed to sf_open.
  64     ** On read, the library fills this struct with information about the file.
  65     ** On write, the struct must be filled in before calling sf_open.
  66     */
  67     SF_INFO             sfinfo ;
  68     int                 readcount ;
  69     const char  *infilename = "input.wav" ;
  70     const char  *outfilename = "output.wav" ;
  71
  72     /* Here's where we open the input file. We pass sf_open the file name and
  73     ** a pointer to an SF_INFO struct.
  74     ** On successful open, sf_open returns a SNDFILE* pointer which is used
  75     ** for all subsequent operations on that file.
  76     ** If an error occurs during sf_open, the function returns a NULL pointer.
  77         **
  78         ** If you are trying to open a raw headerless file you will need to set the
  79         ** format and channels fields of sfinfo before calling sf_open(). For
  80         ** instance to open a raw 16 bit stereo PCM file you would need the following
  81         ** two lines:
  82         **
  83         **              sfinfo.format   = SF_FORMAT_RAW | SF_FORMAT_PCM_16 ;
  84         **              sfinfo.channels = 2 ;
  85     */
  86     if (! (infile = sf_open (infilename, SFM_READ, &sfinfo)))
  87     {   /* Open failed so print an error message. */
  88         printf ("Not able to open input file %s.\n", infilename) ;
  89         /* Print the error message from libsndfile. */
  90         puts (sf_strerror (NULL)) ;
  91         return  1 ;
  92         } ;
  93
  94     if (sfinfo.channels > MAX_CHANNELS)
  95     {   printf ("Not able to process more than %d channels\n", MAX_CHANNELS) ;
  96         return  1 ;
  97         } ;
  98     /* Open the output file. */
  99     if (! (outfile = sf_open (outfilename, SFM_WRITE, &sfinfo)))
 100     {   printf ("Not able to open output file %s.\n", outfilename) ;
 101         puts (sf_strerror (NULL)) ;
 102         return  1 ;
 103         } ;
 104
 105     /* While there are.frames in the input file, read them, process
 106     ** them and write them to the output file.
 107     */
 108     while ((readcount = sf_read_double (infile, data, BUFFER_LEN)))
 109     {   process_data (data, readcount, sfinfo.channels) ;
 110         sf_write_double (outfile, data, readcount) ;
 111         } ;
 112
 113     /* Close input and output files. */
 114     sf_close (infile) ;
 115     sf_close (outfile) ;
 116
 117     return 0 ;
 118 } /* main */
 119
 120 static void
 121 process_data (double *data, int count, int channels)
 122 {       double channel_gain [MAX_CHANNELS] = { 0.5, 0.8, 0.1, 0.4, 0.4, 0.9 } ;
 123     int k, chan ;
 124
 125     /* Process the data here.
 126     ** If the soundfile contains more then 1 channel you need to take care of
 127     ** the data interleaving youself.
 128     ** Current we just apply a channel dependant gain.
 129     */
 130
 131     for (chan = 0 ; chan < channels ; chan ++)
 132         for (k = chan ; k < count ; k+= channels)
 133             data [k] *= channel_gain [chan] ;
 134
 135     return ;
 136 } /* process_data */
 137