/* ** Copyright (C) 1999-2001 Erik de Castro Lopo ** ** 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 #include #include #include "check_log_buffer.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) ; } ; check_log_buffer (file) ; 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) ; } ; check_log_buffer (file) ; 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 */