ref: 4410ad69b1239491424d6d74bc48e2eda6054681
dir: /common/libsndfile/tests/ulaw_test.c/
/*
** Copyright (C) 1999-2000 Erik de Castro Lopo <erikd@zip.com.au>
**
** 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 <stdio.h>
#include <unistd.h>
#include <sndfile.h>
#define BUFFER_SIZE (65536)
static unsigned char ulaw_encode (int sample) ;
static int ulaw_decode (unsigned int ulawbyte) ;
static short short_buffer [BUFFER_SIZE] ;
static unsigned char ulaw_buffer [BUFFER_SIZE] ;
int main (int argc, char *argv[])
{ SNDFILE *file ;
SF_INFO sfinfo ;
char *filename ;
int k ;
filename = "test.au" ;
sfinfo.format = SF_FORMAT_AU | SF_FORMAT_ULAW ;
sfinfo.samplerate = 44100 ;
sfinfo.samples = 123456789 ; /* Wrong length. Library should correct this on sf_close. */
sfinfo.channels = 1 ;
sfinfo.pcmbitwidth = 16 ;
if (! (file = sf_open_write (filename, &sfinfo)))
{ printf ("sf_open_write failed with error : ") ;
sf_perror (NULL) ;
exit (1) ;
} ;
/* Generate a file containing all possible 16 bit sample values
** and write it to disk as ulaw encoded samples.
*/
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 ulaw encoded sample values
** with what they should be.
*/
if (! (file = sf_open_read (filename, &sfinfo)))
{ printf ("sf_open_write failed with error : ") ;
sf_perror (NULL) ;
exit (1) ;
} ;
if (sf_read_raw (file, ulaw_buffer, BUFFER_SIZE) != BUFFER_SIZE)
{ printf ("sf_read_raw : ") ;
sf_perror (file) ;
exit (1) ;
} ;
for (k = 0 ; k < 0x10000 ; k++)
if (ulaw_encode (short_buffer [k]) != ulaw_buffer [k])
{ printf ("Encoder error : sample #%d (0x%02X should be 0x%02X)\n", k, ulaw_buffer [k], ulaw_encode (short_buffer [k])) ;
exit (1) ;
} ;
sf_close (file) ;
printf (" ulaw_test : encoder ... ok\n") ;
/* Now generate a file containing all possible 8 bit encoded
** sample values and write it to disk as ulaw encoded samples.
*/
if (! (file = sf_open_write (filename, &sfinfo)))
{ printf ("sf_open_write failed with error : ") ;
sf_perror (NULL) ;
exit (1) ;
} ;
for (k = 0 ; k < 256 ; k++)
ulaw_buffer [k] = k & 0xFF ;
sf_write_raw (file, ulaw_buffer, 256) ;
sf_close (file) ;
/* Now open that file and compare the ulaw decoded sample values
** with what they should be.
*/
if (! (file = sf_open_read (filename, &sfinfo)))
{ printf ("sf_open_write failed with error : ") ;
sf_perror (NULL) ;
exit (1) ;
} ;
if (sf_read_short (file, short_buffer, 256) != 256)
{ printf ("sf_read_short : ") ;
sf_perror (file) ;
exit (1) ;
} ;
for (k = 0 ; k < 256 ; k++)
if (short_buffer [k] != ulaw_decode (ulaw_buffer [k]))
{ printf ("Decoder error : sample #%d (0x%04X should be 0x%04X)\n", k, short_buffer [k], ulaw_decode (ulaw_buffer [k])) ;
exit (1) ;
} ;
sf_close (file) ;
printf (" ulaw_test : decoder ... ok\n") ;
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.
*/
/*
** This routine converts from linear to ulaw.
**
** Craig Reese: IDA/Supercomputing Research Center
** Joe Campbell: Department of Defense
** 29 September 1989
**
** References:
** 1) CCITT Recommendation G.711 (very difficult to follow)
** 2) "A New Digital Technique for Implementation of Any
** Continuous PCM Companding Law," Villeret, Michel,
** et al. 1973 IEEE Int. Conf. on Communications, Vol 1,
** 1973, pg. 11.12-11.17
** 3) MIL-STD-188-113,"Interoperability and Performance Standards
** for Analog-to_Digital Conversion Techniques,"
** 17 February 1987
**
** Input: Signed 16 bit linear sample
** Output: 8 bit ulaw sample
*/
#define uBIAS 0x84 /* define the add-in bias for 16 bit samples */
#define uCLIP 32635
static
unsigned char ulaw_encode (int sample)
{ static int exp_lut[256] = {0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
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,
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,
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 ulawbyte;
/* Get the sample into sign-magnitude. */
sign = (sample >> 8) & 0x80 ; /* set aside the sign */
if ( sign != 0 )
sample = -sample ; /* get magnitude */
if ( sample > uCLIP )
sample = uCLIP ; /* clip the magnitude */
/* Convert from 16 bit linear to ulaw. */
sample = sample + uBIAS;
exponent = exp_lut[( sample >> 7 ) & 0xFF];
mantissa = ( sample >> ( exponent + 3 ) ) & 0x0F;
ulawbyte = ~ ( sign | ( exponent << 4 ) | mantissa );
return ulawbyte;
} /* ulaw_encode */
/*
** This routine converts from ulaw to 16 bit linear.
**
** Craig Reese: IDA/Supercomputing Research Center
** 29 September 1989
**
** References:
** 1) CCITT Recommendation G.711 (very difficult to follow)
** 2) MIL-STD-188-113,"Interoperability and Performance Standards
** for Analog-to_Digital Conversion Techniques,"
** 17 February 1987
**
** Input: 8 bit ulaw sample
** Output: signed 16 bit linear sample
*/
static
int ulaw_decode (unsigned int ulawbyte)
{ static int exp_lut[8] = { 0, 132, 396, 924, 1980, 4092, 8316, 16764 };
int sign, exponent, mantissa, sample;
ulawbyte = ~ ulawbyte ;
sign = (ulawbyte & 0x80) ;
exponent = (ulawbyte >> 4) & 0x07 ;
mantissa = ulawbyte & 0x0F ;
sample = exp_lut [exponent] + (mantissa << (exponent + 3)) ;
if ( sign != 0 )
sample = -sample ;
return sample;
} /* ulaw_decode */