/*
* encode.c
*
* Usage : encode infile outfile1 outfile2
*/
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <math.h>
/* External function definitions. */
extern void g72x_init_state( struct g72x_state *state_ptr );
extern int g721_encoder( int sl, struct g72x_state *state_ptr, int al, FILE *fpw3 );
extern int g721_decoder( int i, struct g72x_state *state_ptr, int al );
int predictor_zero(struct g72x_state *state_ptr );
int predictor_pole(struct g72x_state *state_ptr );
static int quan( int val, short *table, int size );
static int fmult( int an, int srn );
int step_size( struct g72x_state *state_ptr, int al );
int quantize( int d, int y, short *table, int size );
static int search( int val, short *table, int size );
int reconstruct( int sign, long dqln, int y );
void update( int code_size, int y, long wi, int fi, int dq, int sr, int dqsez, struct g72x_state *state_ptr );
int pack_output( unsigned code, FILE *fpw );
int unpack_input( unsigned char *code, FILE *fpr );
static short seg_end[8] = {0xFF, 0x1FF, 0x3FF, 0x7FF,
0xFFF, 0x1FFF, 0x3FFF, 0x7FFF};
static short qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400};
/*
* Maps G.721 code word to reconstructed scale factor normalized log
* magnitude values.
*/
static long _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425,
425, 373, 323, 273, 213, 135, 4, -2048};
/* Maps G.721 code word to log of scale factor multiplier. */
static long _witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122,
1122, 355, 198, 112, 64, 41, 18, -12};
/*
* Maps G.721 code words to a set of values whose long and short
* term averages are computed and then compared to give an indication
* how stationary (steady state) the signal is.
*/
static short _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};
static short power2[15] = {1, 2, 4, 8, 0x10, 0x20, 0x40, 0x80,
0x100, 0x200, 0x400, 0x800, 0x1000, 0x2000, 0x4000};
struct g72x_state {
long yl; /* Locked or steady state step size multiplier. */
short yu; /* Unlocked or non-steady state step size multiplier. */
short dms; /* Short term energy estimate. */
short dml; /* Long term energy estimate. */
short ap; /* Linear weighting coefficient of 'yl' and 'yu'. */
short a[2]; /* Coefficients of pole portion of prediction filter. */
short b[6]; /* Coefficients of zero portion of prediction filter. */
short pk[2]; /*
* Signs of previous two samples of a partially
* reconstructed signal.
*/
short dq[6]; /*
* Previous 6 samples of the quantized difference
* signal represented in an internal floating point
* format.
*/
short sr[2]; /*
* Previous 2 samples of the quantized difference
* signal represented in an internal floating point
* format.
*/
char td; /* delayed tone detect, new in 1988 version */
};
/*
* g72x_init_state()
*
* This routine initializes and/or resets the g72x_state structure
* pointed to by 'state_ptr'.
* All the initial state values are specified in the CCITT G.721 document.
*/
void
g72x_init_state( state_ptr)
struct g72x_state *state_ptr;
{
int cnta;
state_ptr->yl = 34816;
state_ptr->yu = 544;
state_ptr->dms = 0;
state_ptr->dml = 0;
state_ptr->ap = 0;
for (cnta = 0; cnta < 2; cnta++) {
state_ptr->a[cnta] = 0;
state_ptr->pk[cnta] = 0;
state_ptr->sr[cnta] = 32;
}
for (cnta = 0; cnta < 6; cnta++) {
state_ptr->b[cnta] = 0;
state_ptr->dq[cnta] = 32;
}
state_ptr->td = 0;
}
/*
* g721_encoder()
*
* Encodes the input vale of linear PCM, A-law or u-law data sl and returns
* the resulting code. -1 is returned for unknown input coding value.
*/
int
g721_encoder( sl, state_ptr, al, fpw3 )
int sl;
struct g72x_state *state_ptr;
int al;
FILE *fpw3;
{
long wi;
short fi;
short dq;
short sezi, se, sez; /* ACCUM */
short d; /* SUBTA */
short sr; /* ADDB */
short y; /* MIX */
short dqsez; /* ADDC */
short i;
short tmp;
// int size;
sl >>= 2; /* 14-bit dynamic range */
sezi = predictor_zero(state_ptr);
sez = sezi >> 1;
se = (sezi + predictor_pole(state_ptr)) >> 1; /* estimated signal */
d = sl - se; /* estimation difference */
/* quantize the prediction difference */
y = step_size(state_ptr, al); /* quantizer step size */
i = quantize(d, y, qtab_721, 7); /* i = ADPCM code */
dq = reconstruct(i & 8, _dqlntab[i], y); /* quantized est diff */
sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconst. signal */
dqsez = sr + sez - se; /* pole prediction diff. */
update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
return (i);
}
int
g721_decoder( i, state_ptr, al )
int i;
struct g72x_state *state_ptr;
int al;
{
short sezi, sei, sez, se; /* ACCUM */
short y; /* MIX */
short sr; /* ADDB */
short dq;
short dqsez;
i &= 0x0f; /* mask to get proper bits */
sezi = predictor_zero(state_ptr);
sez = sezi >> 1;
sei = sezi + predictor_pole(state_ptr);
se = sei >> 1; /* se = estimated signal */
y = step_size(state_ptr, al); /* dynamic quantizer step size */
dq = reconstruct(i & 0x08, _dqlntab[i], y); /* quantized diff. */
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : se + dq; /* reconst. signal */
dqsez = sr - se + sez; /* pole prediction diff. */
update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
return (sr << 2); /* sr was 14-bit dynamic range */
}
/*
* predictor_zero()
*
* computes the estimated signal from 6-zero predictor.
*
*/
int
predictor_zero( state_ptr )
struct g72x_state *state_ptr;
{
int i;
int sezi;
sezi = fmult(state_ptr->b[0] >> 2, state_ptr->dq[0]);
for (i = 1; i < 6; i++) /* ACCUM */
sezi += fmult(state_ptr->b[i] >> 2, state_ptr->dq[i]);
return (sezi);
}
/*
* predictor_pole()
*
* computes the estimated signal from 2-pole predictor.
*
*/
int
predictor_pole( state_ptr )
struct g72x_state *state_ptr;
{
return (fmult(state_ptr->a[1] >> 2, state_ptr->sr[1]) +
fmult(state_ptr->a[0] >> 2, state_ptr->sr[0]));
}
/*
* quan()
*
* quantizes the input val against the table of size short integers.
* It returns i if table[i - 1] <= val < table[i].
*
* Using linear search for simple coding.
*/
static int
quan( val, table, size)
int val;
short *table;
int size;
{
int i;
for (i = 0; i < size; i++)
if (val < *table++)
break;
return (i);
}
/*
* fmult()
*
* returns the integer product of the 14-bit integer "an" and
* "floating point" representation (4-bit exponent, 6-bit mantessa) "srn".
*/
static int
fmult( an, srn )
int an;
int srn;
{
short anexp;
short anmag, anmant;
short wanexp, wanmag, wanmant;
short retval;
anmag = (an > 0) ? an : ((-an) & 0x1FFF);
anexp = quan(anmag, power2, 15) - 6;
anmant = (anmag == 0) ? 32 :
(anexp >= 0) ? (long)anmag >> anexp :(long)anmag << -anexp;
wanexp = anexp + (((long)srn >> 6) & 0xF) - 13;
wanmant = (anmant * (srn & 0x3f) + 0x30) >> 4;
retval = (wanexp >= 0) ? (((long)wanmant << wanexp) & 0x7FFF) :
((long)wanmant >> -wanexp);
return (((an ^ srn) < 0) ? -retval : retval);
}
/*
* step_size()
*
* computes the quantization step size of the adaptive quantizer.
*
*/
int
step_size( state_ptr, al )
struct g72x_state *state_ptr;
int al;
{
int y;
int dif;
if (state_ptr->ap >= 256)
return (state_ptr->yu);
else {
y = state_ptr->yl >> 6;
dif = state_ptr->yu - y;
al = state_ptr->ap >> 2;
if (dif > 0)
y += (dif * al) >> 6;
else if (dif < 0)
y += (dif * al + 0x3F) >> 6;
return (y);
}
}
/*
* quantize()
*
* Given a raw sample, 'd', of the difference signal and a
* quantization step size scale factor, 'y', this routine returns the
* ADPCM codeword