143 lines
4.9 KiB
C
143 lines
4.9 KiB
C
/*
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** Copyright (C) 2001-2013 Erik de Castro Lopo <erikd@mega-nerd.com>
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**
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** All rights reserved.
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**
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** Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions are
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** met:
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**
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** * Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** * Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in
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** the documentation and/or other materials provided with the
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** distribution.
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** * Neither the author nor the names of any contributors may be used
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** to endorse or promote products derived from this software without
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** specific prior written permission.
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**
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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** TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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** PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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** EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdio.h>
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#include <string.h>
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/* Include this header file to use functions from libsndfile. */
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#include <sndfile.h>
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/* This will be the length of the buffer used to hold.frames while
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** we process them.
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*/
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#define BUFFER_LEN 1024
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/* libsndfile can handle more than 6 channels but we'll restrict it to 6. */
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#define MAX_CHANNELS 6
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/* Function prototype. */
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static void process_data (double *data, int count, int channels) ;
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int
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main (void)
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{ /* This is a buffer of double precision floating point values
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** which will hold our data while we process it.
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*/
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static double data [BUFFER_LEN] ;
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/* A SNDFILE is very much like a FILE in the Standard C library. The
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** sf_open function return an SNDFILE* pointer when they sucessfully
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** open the specified file.
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*/
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SNDFILE *infile, *outfile ;
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/* A pointer to an SF_INFO struct is passed to sf_open.
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** On read, the library fills this struct with information about the file.
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** On write, the struct must be filled in before calling sf_open.
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*/
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SF_INFO sfinfo ;
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int readcount ;
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const char *infilename = "input.wav" ;
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const char *outfilename = "output.wav" ;
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/* The SF_INFO struct must be initialized before using it.
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*/
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memset (&sfinfo, 0, sizeof (sfinfo)) ;
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/* Here's where we open the input file. We pass sf_open the file name and
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** a pointer to an SF_INFO struct.
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** On successful open, sf_open returns a SNDFILE* pointer which is used
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** for all subsequent operations on that file.
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** If an error occurs during sf_open, the function returns a NULL pointer.
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**
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** If you are trying to open a raw headerless file you will need to set the
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** format and channels fields of sfinfo before calling sf_open(). For
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** instance to open a raw 16 bit stereo PCM file you would need the following
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** two lines:
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**
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** sfinfo.format = SF_FORMAT_RAW | SF_FORMAT_PCM_16 ;
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** sfinfo.channels = 2 ;
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*/
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if (! (infile = sf_open (infilename, SFM_READ, &sfinfo)))
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{ /* Open failed so print an error message. */
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printf ("Not able to open input file %s.\n", infilename) ;
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/* Print the error message from libsndfile. */
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puts (sf_strerror (NULL)) ;
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return 1 ;
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} ;
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if (sfinfo.channels > MAX_CHANNELS)
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{ printf ("Not able to process more than %d channels\n", MAX_CHANNELS) ;
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return 1 ;
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} ;
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/* Open the output file. */
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if (! (outfile = sf_open (outfilename, SFM_WRITE, &sfinfo)))
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{ printf ("Not able to open output file %s.\n", outfilename) ;
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puts (sf_strerror (NULL)) ;
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return 1 ;
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} ;
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/* While there are.frames in the input file, read them, process
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** them and write them to the output file.
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*/
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while ((readcount = sf_read_double (infile, data, BUFFER_LEN)))
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{ process_data (data, readcount, sfinfo.channels) ;
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sf_write_double (outfile, data, readcount) ;
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} ;
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/* Close input and output files. */
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sf_close (infile) ;
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sf_close (outfile) ;
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return 0 ;
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} /* main */
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static void
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process_data (double *data, int count, int channels)
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{ double channel_gain [MAX_CHANNELS] = { 0.5, 0.8, 0.1, 0.4, 0.4, 0.9 } ;
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int k, chan ;
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/* Process the data here.
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** If the soundfile contains more then 1 channel you need to take care of
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** the data interleaving youself.
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** Current we just apply a channel dependant gain.
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*/
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for (chan = 0 ; chan < channels ; chan ++)
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for (k = chan ; k < count ; k+= channels)
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data [k] *= channel_gain [chan] ;
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return ;
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} /* process_data */
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