256 lines
7.1 KiB
C
256 lines
7.1 KiB
C
/*
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** Copyright (C) 1999-2009 Erik de Castro Lopo <erikd@mega-nerd.com>
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**
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** This program is free software; you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation; either version 2 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software
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** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include "sfconfig.h"
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#include <stdio.h>
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#include <stdlib.h>
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <sndfile.h>
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#include "utils.h"
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#define BUFFER_SIZE (65536)
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static unsigned char ulaw_encode (int sample) ;
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static int ulaw_decode (unsigned int ulawbyte) ;
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static short short_buffer [BUFFER_SIZE] ;
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static unsigned char ulaw_buffer [BUFFER_SIZE] ;
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int
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main (void)
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{ SNDFILE *file ;
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SF_INFO sfinfo ;
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const char *filename ;
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int k ;
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filename = "test.raw" ;
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sfinfo.format = SF_FORMAT_RAW | SF_FORMAT_ULAW ;
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sfinfo.samplerate = 44100 ;
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sfinfo.frames = 123456789 ;
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sfinfo.channels = 1 ;
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if ((file = sf_open (filename, SFM_WRITE, &sfinfo)) == NULL)
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{ printf ("sf_open_write failed with error : ") ;
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fflush (stdout) ;
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puts (sf_strerror (NULL)) ;
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exit (1) ;
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} ;
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/* Generate a file containing all possible 16 bit sample values
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** and write it to disk as ulaw encoded.frames.
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*/
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for (k = 0 ; k < 0x10000 ; k++)
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short_buffer [k] = k & 0xFFFF ;
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sf_write_short (file, short_buffer, BUFFER_SIZE) ;
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sf_close (file) ;
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/* Now open that file and compare the ulaw encoded sample values
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** with what they should be.
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*/
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if ((file = sf_open (filename, SFM_READ, &sfinfo)) == NULL)
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{ printf ("sf_open_write failed with error : ") ;
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puts (sf_strerror (NULL)) ;
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exit (1) ;
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} ;
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check_log_buffer_or_die (file, __LINE__) ;
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if (sf_read_raw (file, ulaw_buffer, BUFFER_SIZE) != BUFFER_SIZE)
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{ printf ("sf_read_raw : ") ;
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puts (sf_strerror (file)) ;
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exit (1) ;
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} ;
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for (k = 0 ; k < 0x10000 ; k++)
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if (ulaw_encode (short_buffer [k]) != ulaw_buffer [k])
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{ printf ("Encoder error : sample #%d (0x%02X should be 0x%02X)\n", k, ulaw_buffer [k], ulaw_encode (short_buffer [k])) ;
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exit (1) ;
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} ;
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sf_close (file) ;
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printf (" ulaw_test : encoder ... ok\n") ;
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/* Now generate a file containing all possible 8 bit encoded
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** sample values and write it to disk as ulaw encoded.frames.
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*/
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if (! (file = sf_open (filename, SFM_WRITE, &sfinfo)))
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{ printf ("sf_open_write failed with error : ") ;
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puts (sf_strerror (NULL)) ;
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exit (1) ;
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} ;
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for (k = 0 ; k < 256 ; k++)
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ulaw_buffer [k] = k & 0xFF ;
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sf_write_raw (file, ulaw_buffer, 256) ;
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sf_close (file) ;
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/* Now open that file and compare the ulaw decoded sample values
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** with what they should be.
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*/
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if (! (file = sf_open (filename, SFM_READ, &sfinfo)))
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{ printf ("sf_open_write failed with error : ") ;
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puts (sf_strerror (NULL)) ;
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exit (1) ;
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} ;
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check_log_buffer_or_die (file, __LINE__) ;
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if (sf_read_short (file, short_buffer, 256) != 256)
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{ printf ("sf_read_short : ") ;
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puts (sf_strerror (file)) ;
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exit (1) ;
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} ;
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for (k = 0 ; k < 256 ; k++)
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if (short_buffer [k] != ulaw_decode (ulaw_buffer [k]))
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{ printf ("Decoder error : sample #%d (0x%04X should be 0x%04X)\n", k, short_buffer [k], ulaw_decode (ulaw_buffer [k])) ;
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exit (1) ;
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} ;
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sf_close (file) ;
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printf (" ulaw_test : decoder ... ok\n") ;
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unlink (filename) ;
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return 0 ;
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} /* main */
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/*=================================================================================
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** The following routines came from the sox-12.15 (Sound eXcahcnge) distribution.
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**
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** This code is not compiled into libsndfile. It is only used to test the
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** libsndfile lookup tables for correctness.
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**
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** I have included the original authors comments.
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*/
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/*
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** This routine converts from linear to ulaw.
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**
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** Craig Reese: IDA/Supercomputing Research Center
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** Joe Campbell: Department of Defense
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** 29 September 1989
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**
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** References:
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** 1) CCITT Recommendation G.711 (very difficult to follow)
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** 2) "A New Digital Technique for Implementation of Any
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** Continuous PCM Companding Law," Villeret, Michel,
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** et al. 1973 IEEE Int. Conf. on Communications, Vol 1,
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** 1973, pg. 11.12-11.17
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** 3) MIL-STD-188-113,"Interoperability and Performance Standards
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** for Analog-to_Digital Conversion Techniques,"
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** 17 February 1987
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**
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** Input: Signed 16 bit linear sample
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** Output: 8 bit ulaw sample
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*/
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#define uBIAS 0x84 /* define the add-in bias for 16 bit.frames */
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#define uCLIP 32635
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static
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unsigned char ulaw_encode (int sample)
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{ static int exp_lut [256] =
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{ 0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
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4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
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5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
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5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
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} ;
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int sign, exponent, mantissa ;
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unsigned char ulawbyte ;
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/* Get the sample into sign-magnitude. */
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sign = (sample >> 8) & 0x80 ; /* set aside the sign */
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if ( sign != 0 )
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sample = -sample ; /* get magnitude */
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if ( sample > uCLIP )
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sample = uCLIP ; /* clip the magnitude */
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/* Convert from 16 bit linear to ulaw. */
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sample = sample + uBIAS ;
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exponent = exp_lut [( sample >> 7 ) & 0xFF] ;
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mantissa = (sample >> ( exponent + 3 ) ) & 0x0F ;
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ulawbyte = ~ (sign | ( exponent << 4 ) | mantissa) ;
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return ulawbyte ;
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} /* ulaw_encode */
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/*
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** This routine converts from ulaw to 16 bit linear.
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**
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** Craig Reese: IDA/Supercomputing Research Center
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** 29 September 1989
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**
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** References:
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** 1) CCITT Recommendation G.711 (very difficult to follow)
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** 2) MIL-STD-188-113,"Interoperability and Performance Standards
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** for Analog-to_Digital Conversion Techniques,"
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** 17 February 1987
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**
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** Input: 8 bit ulaw sample
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** Output: signed 16 bit linear sample
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*/
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static
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int ulaw_decode (unsigned int ulawbyte)
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{ static int exp_lut [8] = { 0, 132, 396, 924, 1980, 4092, 8316, 16764 } ;
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int sign, exponent, mantissa, sample ;
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ulawbyte = ~ ulawbyte ;
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sign = (ulawbyte & 0x80) ;
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exponent = (ulawbyte >> 4) & 0x07 ;
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mantissa = ulawbyte & 0x0F ;
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sample = exp_lut [exponent] + (mantissa << (exponent + 3)) ;
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if (sign != 0)
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sample = -sample ;
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return sample ;
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} /* ulaw_decode */
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