ref: 0d060442250e7966087cc4e1678cf46ea5978671
dir: /src/speech/cst_wave_utils.c/
/*************************************************************************/
/* */
/* Language Technologies Institute */
/* Carnegie Mellon University */
/* Copyright (c) 2000 */
/* All Rights Reserved. */
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/* */
/* CARNEGIE MELLON UNIVERSITY AND THE CONTRIBUTORS TO THIS WORK */
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/* */
/*************************************************************************/
/* Author: Alan W Black (awb@cs.cmu.edu) */
/* Date: October 2000 */
/*************************************************************************/
/* */
/* Convertion routines for various waveform encodings */
/* */
/* This contains software written external to Flite */
/* ulaw code came via the Edinburgh Speech Tools */
/* g72x codec came from Sun Microsystems */
/* */
/*************************************************************************/
#include "g72x.h"
/*
** 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 ZEROTRAP /* turn on the trap as per the MIL-STD */
#define BIAS 0x84 /* define the add-in bias for 16 bit samples */
#define CLIP 32635
unsigned char cst_short_to_ulaw(short sample)
{
static const 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 > CLIP ) sample = CLIP; /* clip the magnitude */
/* Convert from 16 bit linear to ulaw. */
sample = sample + BIAS;
exponent = exp_lut[( sample >> 7 ) & 0xFF];
mantissa = ( sample >> ( exponent + 3 ) ) & 0x0F;
ulawbyte = ~ ( sign | ( exponent << 4 ) | mantissa );
#ifdef ZEROTRAP
if ( ulawbyte == 0 ) ulawbyte = 0x02; /* optional CCITT trap */
#endif
return ulawbyte;
}
/*
** 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
*/
short cst_ulaw_to_short( unsigned char ulawbyte )
{
static const int exp_lut[8] = { 0, 132, 396, 924, 1980, 4092, 8316, 16764 };
int sign, exponent, mantissa;
short 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;
}
unsigned char *cst_g721_decode(int *actual_size,int size,
const unsigned char *packed_residual
)
{
struct g72x_state state;
short sample_short;
unsigned char *unpacked_residual;
unsigned char code, xcode;
int ur=0;
int dec_bits;
*actual_size = size*2;
unpacked_residual = cst_alloc(unsigned char, *actual_size);
g72x_init_state(&state);
dec_bits = 4; /* g721 4-bit encoding */
for (ur=0; ur <*actual_size; ur++)
{
xcode = packed_residual[ur/2];
if (ur % 2 == 0)
code = (xcode & 0xF0) >> dec_bits;
else
code = (xcode & 0x0F);
sample_short = g721_decoder(code,AUDIO_ENCODING_LINEAR,&state);
unpacked_residual[ur] = cst_short_to_ulaw(sample_short);
}
return unpacked_residual;
}
unsigned char *cst_g721_encode(int *packed_size,int actual_size,
const unsigned char *unpacked_residual
)
{
struct g72x_state state;
unsigned char *packed_residual;
unsigned char code, xcode=0;
int ur=0;
int dec_bits;
*packed_size = (actual_size+1)/2; /* will round down to even number */
packed_residual = cst_alloc(unsigned char, *packed_size);
g72x_init_state(&state);
dec_bits = 4; /* g721 4-bit encoding */
for (ur=0; ur < actual_size; ur++)
{
code = g721_encoder((int)cst_ulaw_to_short(unpacked_residual[ur]),
AUDIO_ENCODING_LINEAR,&state);
if (ur % 2 == 0)
{
xcode = 0;
xcode = code << dec_bits;
}
else
{
xcode += code;
packed_residual[ur/2] = xcode;
}
}
return packed_residual;
}