libsnd/tests/alaw_test.c

/*
** Copyright (C) 1999-2012 Erik de Castro Lopo <erikd@mega-nerd.com>
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

#include "sfconfig.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if HAVE_UNISTD_H
#include <unistd.h>
#else
#include "sf_unistd.h"
#endif

#include <sndfile.h>

#include "utils.h"

#define	BUFFER_SIZE		(65536)

static unsigned char	alaw_encode (int sample) ;
static int				alaw_decode (unsigned int alawbyte) ;

static	short			short_buffer [BUFFER_SIZE] ;
static	unsigned char	alaw_buffer [BUFFER_SIZE] ;

int
main (void)
{	SNDFILE		*file ;
	SF_INFO		sfinfo ;
	const char	*filename ;
	int			k ;

	print_test_name ("alaw_test", "encoder") ;

	filename = "alaw_test.raw" ;

	sf_info_setup (&sfinfo, SF_FORMAT_RAW | SF_FORMAT_ALAW, 44100, 1) ;

	if ((file = sf_open (filename, SFM_WRITE, &sfinfo)) == NULL)
	{	printf ("sf_open_write failed with error : ") ;
		fflush (stdout) ;
		puts (sf_strerror (NULL)) ;
		exit (1) ;
		} ;

	/* Generate a file containing all possible 16 bit sample values
	** and write it to disk as alaw encoded.frames.
	*/

	for (k = 0 ; k < 0x10000 ; k++)
		short_buffer [k] = k & 0xFFFF ;

	sf_write_short (file, short_buffer, BUFFER_SIZE) ;
	sf_close (file) ;

	/* Now open that file and compare the alaw encoded sample values
	** with what they should be.
	*/

	if ((file = sf_open (filename, SFM_READ, &sfinfo)) == NULL)
	{	printf ("sf_open_write failed with error : ") ;
		puts (sf_strerror (NULL)) ;
		exit (1) ;
		} ;

	check_log_buffer_or_die (file, __LINE__) ;

	if (sf_read_raw (file, alaw_buffer, BUFFER_SIZE) != BUFFER_SIZE)
	{	printf ("sf_read_raw : ") ;
		puts (sf_strerror (file)) ;
		exit (1) ;
		} ;

	for (k = 0 ; k < 0x10000 ; k++)
		if (alaw_encode (short_buffer [k]) != alaw_buffer [k])
		{	printf ("Encoder error : sample #%d (0x%02X should be 0x%02X)\n", k, alaw_buffer [k], alaw_encode (short_buffer [k])) ;
			exit (1) ;
			} ;

	sf_close (file) ;

	puts ("ok") ;

	print_test_name ("alaw_test", "decoder") ;
	/* Now generate a file containing all possible 8 bit encoded
	** sample values and write it to disk as alaw encoded.frames.
	*/

	if (! (file = sf_open (filename, SFM_WRITE, &sfinfo)))
	{	printf ("sf_open_write failed with error : ") ;
		puts (sf_strerror (NULL)) ;
		exit (1) ;
		} ;

	for (k = 0 ; k < 256 ; k++)
		alaw_buffer [k] = k & 0xFF ;

	sf_write_raw (file, alaw_buffer, 256) ;
	sf_close (file) ;

	/* Now open that file and compare the alaw decoded sample values
	** with what they should be.
	*/

	if (! (file = sf_open (filename, SFM_READ, &sfinfo)))
	{	printf ("sf_open_write failed with error : ") ;
		puts (sf_strerror (NULL)) ;
		exit (1) ;
		} ;

	check_log_buffer_or_die (file, __LINE__) ;

	if (sf_read_short (file, short_buffer, 256) != 256)
	{	printf ("sf_read_short : ") ;
		puts (sf_strerror (file)) ;
		exit (1) ;
		} ;


	for (k = 0 ; k < 256 ; k++)
		if (short_buffer [k] != alaw_decode (alaw_buffer [k]))
		{	printf ("Decoder error : sample #%d (0x%02X should be 0x%02X)\n", k, short_buffer [k], alaw_decode (alaw_buffer [k])) ;
			exit (1) ;
			} ;

	sf_close (file) ;

	puts ("ok") ;

	unlink (filename) ;

	return 0 ;
} /* main */


/*=================================================================================
**	The following routines came from the sox-12.15 (Sound eXcahcnge) distribution.
**
**	This code is not compiled into libsndfile. It is only used to test the
**	libsndfile lookup tables for correctness.
**
**	I have included the original authors comments.
*/

/*
** A-law routines by Graeme W. Gill.
** Date: 93/5/7
**
** References:
** 1) CCITT Recommendation G.711
**
*/

#define ACLIP 31744

static
unsigned char alaw_encode (int sample)
{	static int exp_lut [128] =
	{	1, 1, 2, 2, 3, 3, 3, 3,
		4, 4, 4, 4, 4, 4, 4, 4,
		5, 5, 5, 5, 5, 5, 5, 5,
		5, 5, 5, 5, 5, 5, 5, 5,
		6, 6, 6, 6, 6, 6, 6, 6,
		6, 6, 6, 6, 6, 6, 6, 6,
		6, 6, 6, 6, 6, 6, 6, 6,
		6, 6, 6, 6, 6, 6, 6, 6,
		7, 7, 7, 7, 7, 7, 7, 7,
		7, 7, 7, 7, 7, 7, 7, 7,
		7, 7, 7, 7, 7, 7, 7, 7,
		7, 7, 7, 7, 7, 7, 7, 7,
		7, 7, 7, 7, 7, 7, 7, 7,
		7, 7, 7, 7, 7, 7, 7, 7,
		7, 7, 7, 7, 7, 7, 7, 7,
		7, 7, 7, 7, 7, 7, 7, 7
		} ;

	int sign, exponent, mantissa ;
	unsigned char Alawbyte ;

	/* Get the sample into sign-magnitude. */
	sign = ((~sample) >> 8) & 0x80 ;			/* set aside the sign */
	if (sign == 0)
		sample = -sample ;		/* get magnitude */
	if (sample > ACLIP)
		sample = ACLIP ;						/* clip the magnitude */

	/* Convert from 16 bit linear to ulaw. */
	if (sample >= 256)
	{	exponent = exp_lut [(sample >> 8) & 0x7F] ;
		mantissa = (sample >> (exponent + 3)) & 0x0F ;
		Alawbyte = ((exponent << 4) | mantissa) ;
		}
	else
		Alawbyte = (sample >> 4) ;

	Alawbyte ^= (sign ^ 0x55) ;

	return Alawbyte ;
} /* alaw_encode */

static
int alaw_decode (unsigned int Alawbyte)
{	static int exp_lut [8] = { 0, 264, 528, 1056, 2112, 4224, 8448, 16896 } ;
	int sign, exponent, mantissa, sample ;

	Alawbyte ^= 0x55 ;
	sign = (Alawbyte & 0x80) ;
	Alawbyte &= 0x7f ;			/* get magnitude */
	if (Alawbyte >= 16)
	{	exponent = (Alawbyte >> 4) & 0x07 ;
		mantissa = Alawbyte & 0x0F ;
		sample = exp_lut [exponent] + (mantissa << (exponent + 3)) ;
		}
	else
		sample = (Alawbyte << 4) + 8 ;
	if (sign == 0)
		sample = -sample ;

	return sample ;
} /* alaw_decode */