comparison src/libsndfile-1.0.27/examples/sfprocess.c @ 40:1df64224f5ac

Current libsndfile source

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