libsndfile/tests/ulaw_test.c

   1 /*
   2 ** Copyright (C) 1999-2003 Erik de Castro Lopo <erikd@zip.com.au>
   3 **
   4 ** This program is free software; you can redistribute it and/or modify
   5 ** it under the terms of the GNU General Public License as published by
   6 ** the Free Software Foundation; either version 2 of the License, or
   7 ** (at your option) any later version.
   8 **
   9 ** This program is distributed in the hope that it will be useful,
  10 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 ** GNU General Public License for more details.
  13 **
  14 ** You should have received a copy of the GNU General Public License
  15 ** along with this program; if not, write to the Free Software
  16 ** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17 */
  18
  19
  20
  21 #include        <stdio.h>
  22 #include        <unistd.h>
  23
  24 #include        <sndfile.h>
  25
  26 #include        "utils.h"
  27
  28 #define BUFFER_SIZE             (65536)
  29
  30 static unsigned char    ulaw_encode (int sample) ;
  31 static int                              ulaw_decode (unsigned int ulawbyte) ;
  32
  33 static  short                   short_buffer [BUFFER_SIZE] ;
  34 static  unsigned char   ulaw_buffer [BUFFER_SIZE] ;
  35
  36 int
  37 main (void)
  38 {       SNDFILE *file ;
  39         SF_INFO sfinfo ;
  40         char    *filename ;
  41         int             k ;
  42
  43         filename = "test.raw" ;
  44
  45         sfinfo.format      = SF_FORMAT_RAW | SF_FORMAT_ULAW ;
  46         sfinfo.samplerate  = 44100 ;
  47         sfinfo.frames     = 123456789 ;
  48         sfinfo.channels    = 1 ;
  49
  50         if (! (file = sf_open (filename, SFM_WRITE, &sfinfo)))
  51         {       printf ("sf_open_write failed with error : ") ;
  52                 fflush (stdout) ;
  53                 puts (sf_strerror (NULL)) ;
  54                 exit (1) ;
  55                 } ;
  56
  57         /* Generate a file containing all possible 16 bit sample values
  58         ** and write it to disk as ulaw encoded.frames.
  59         */
  60
  61         for (k = 0 ; k < 0x10000 ; k++)
  62                 short_buffer [k] = k & 0xFFFF ;
  63
  64         sf_write_short (file, short_buffer, BUFFER_SIZE) ;
  65         sf_close (file) ;
  66
  67         /* Now open that file and compare the ulaw encoded sample values
  68         ** with what they should be.
  69         */
  70
  71         if (! (file = sf_open (filename, SFM_READ, &sfinfo)))
  72         {       printf ("sf_open_write failed with error : ") ;
  73                 puts (sf_strerror (NULL)) ;
  74                 exit (1) ;
  75                 } ;
  76
  77         check_log_buffer_or_die (file) ;
  78
  79         if (sf_read_raw (file, ulaw_buffer, BUFFER_SIZE) != BUFFER_SIZE)
  80         {       printf ("sf_read_raw : ") ;
  81                 puts (sf_strerror (file)) ;
  82                 exit (1) ;
  83                 } ;
  84
  85         for (k = 0 ; k < 0x10000 ; k++)
  86                 if (ulaw_encode (short_buffer [k]) != ulaw_buffer [k])
  87                 {       printf ("Encoder error : sample #%d (0x%02X should be 0x%02X)\n", k, ulaw_buffer [k], ulaw_encode (short_buffer [k])) ;
  88                         exit (1) ;
  89                         } ;
  90
  91         sf_close (file) ;
  92
  93         printf ("    alaw_test : encoder ... ok\n") ;
  94
  95         /* Now generate a file containing all possible 8 bit encoded
  96         ** sample values and write it to disk as ulaw encoded.frames.
  97         */
  98
  99         if (! (file = sf_open (filename, SFM_WRITE, &sfinfo)))
 100         {       printf ("sf_open_write failed with error : ") ;
 101                 puts (sf_strerror (NULL)) ;
 102                 exit (1) ;
 103                 } ;
 104
 105         for (k = 0 ; k < 256 ; k++)
 106                 ulaw_buffer [k] = k & 0xFF ;
 107
 108         sf_write_raw (file, ulaw_buffer, 256) ;
 109         sf_close (file) ;
 110
 111         /* Now open that file and compare the ulaw decoded sample values
 112         ** with what they should be.
 113         */
 114
 115         if (! (file = sf_open (filename, SFM_READ, &sfinfo)))
 116         {       printf ("sf_open_write failed with error : ") ;
 117                 puts (sf_strerror (NULL)) ;
 118                 exit (1) ;
 119                 } ;
 120
 121         check_log_buffer_or_die (file) ;
 122
 123         if (sf_read_short (file, short_buffer, 256) != 256)
 124         {       printf ("sf_read_short : ") ;
 125                 puts (sf_strerror (file)) ;
 126                 exit (1) ;
 127                 } ;
 128
 129
 130         for (k = 0 ; k < 256 ; k++)
 131                 if (short_buffer [k] != ulaw_decode (ulaw_buffer [k]))
 132                 {       printf ("Decoder error : sample #%d (0x%04X should be 0x%04X)\n", k, short_buffer [k], ulaw_decode (ulaw_buffer [k])) ;
 133                         exit (1) ;
 134                         } ;
 135
 136         sf_close (file) ;
 137
 138         printf ("    ulaw_test : decoder ... ok\n") ;
 139
 140         unlink (filename) ;
 141
 142         return 0 ;
 143 } /* main */
 144
 145
 146 /*=================================================================================
 147 **      The following routines came from the sox-12.15 (Sound eXcahcnge) distribution.
 148 **
 149 **      This code is not compiled into libsndfile. It is only used to test the
 150 **      libsndfile lookup tables for correctness.
 151 **
 152 **      I have included the original authors comments.
 153 */
 154
 155 /*
 156 ** This routine converts from linear to ulaw.
 157 **
 158 ** Craig Reese: IDA/Supercomputing Research Center
 159 ** Joe Campbell: Department of Defense
 160 ** 29 September 1989
 161 **
 162 ** References:
 163 ** 1) CCITT Recommendation G.711  (very difficult to follow)
 164 ** 2) "A New Digital Technique for Implementation of Any
 165 **     Continuous PCM Companding Law," Villeret, Michel,
 166 **     et al. 1973 IEEE Int. Conf. on Communications, Vol 1,
 167 **     1973, pg. 11.12-11.17
 168 ** 3) MIL-STD-188-113,"Interoperability and Performance Standards
 169 **     for Analog-to_Digital Conversion Techniques,"
 170 **     17 February 1987
 171 **
 172 ** Input: Signed 16 bit linear sample
 173 ** Output: 8 bit ulaw sample
 174 */
 175
 176 #define uBIAS 0x84   /* define the add-in bias for 16 bit.frames */
 177 #define uCLIP 32635
 178
 179 static
 180 unsigned char ulaw_encode (int sample)
 181 {       static int exp_lut[256] = {0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
 182                                4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
 183                                5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
 184                                5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
 185                                6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
 186                                6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
 187                                6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
 188                                6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
 189                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 190                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 191                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 192                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 193                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 194                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 195                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 196                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7};
 197     int sign, exponent, mantissa;
 198     unsigned char ulawbyte;
 199
 200     /* Get the sample into sign-magnitude. */
 201     sign = (sample >> 8) & 0x80 ;                                       /* set aside the sign */
 202     if ( sign != 0 )
 203                 sample = -sample ;                                                      /* get magnitude */
 204     if ( sample > uCLIP )
 205                 sample = uCLIP ;                                                        /* clip the magnitude */
 206
 207     /* Convert from 16 bit linear to ulaw. */
 208     sample = sample + uBIAS;
 209     exponent = exp_lut[( sample >> 7 ) & 0xFF];
 210     mantissa = ( sample >> ( exponent + 3 ) ) & 0x0F;
 211     ulawbyte = ~ ( sign | ( exponent << 4 ) | mantissa );
 212
 213         return ulawbyte;
 214 } /* ulaw_encode */
 215
 216
 217 /*
 218 ** This routine converts from ulaw to 16 bit linear.
 219 **
 220 ** Craig Reese: IDA/Supercomputing Research Center
 221 ** 29 September 1989
 222 **
 223 ** References:
 224 ** 1) CCITT Recommendation G.711  (very difficult to follow)
 225 ** 2) MIL-STD-188-113,"Interoperability and Performance Standards
 226 **     for Analog-to_Digital Conversion Techniques,"
 227 **     17 February 1987
 228 **
 229 ** Input: 8 bit ulaw sample
 230 ** Output: signed 16 bit linear sample
 231 */
 232
 233 static
 234 int ulaw_decode (unsigned int ulawbyte)
 235 {       static int exp_lut[8] = { 0, 132, 396, 924, 1980, 4092, 8316, 16764 };
 236     int sign, exponent, mantissa, sample;
 237
 238     ulawbyte = ~ ulawbyte ;
 239     sign = (ulawbyte & 0x80) ;
 240     exponent = (ulawbyte >> 4) & 0x07 ;
 241     mantissa = ulawbyte & 0x0F ;
 242     sample = exp_lut [exponent] + (mantissa << (exponent + 3)) ;
 243     if ( sign != 0 )
 244                 sample = -sample ;
 245
 246     return sample;
 247 } /* ulaw_decode */
 248