kolibrios/programs/media/ac97 mp3/trunk/mp3dec/l3hybrid.c

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#include <math.h>
extern int m_band_limit;
/* "imdct.c" */
void imdct18(float f[]); /* 18 point */
void imdct6_3(float f[]); /* 6 point */
/*-- windows by block type --*/
static float win[4][36];
void hwin_init()
{
int i, j;
double pi;
pi = 4.0 * atan(1.0);
/* type 0 */
for (i = 0; i < 36; i++)
win[0][i] = (float) sin(pi / 36 * (i + 0.5));
/* type 1 */
for (i = 0; i < 18; i++)
win[1][i] = (float) sin(pi / 36 * (i + 0.5));
for (i = 18; i < 24; i++)
win[1][i] = 1.0F;
for (i = 24; i < 30; i++)
win[1][i] = (float) sin(pi / 12 * (i + 0.5 - 18));
for (i = 30; i < 36; i++)
win[1][i] = 0.0F;
/* type 3 */
for (i = 0; i < 6; i++)
win[3][i] = 0.0F;
for (i = 6; i < 12; i++)
win[3][i] = (float) sin(pi / 12 * (i + 0.5 - 6));
for (i = 12; i < 18; i++)
win[3][i] = 1.0F;
for (i = 18; i < 36; i++)
win[3][i] = (float) sin(pi / 36 * (i + 0.5));
/* type 2 */
for (i = 0; i < 12; i++)
win[2][i] = (float) sin(pi / 12 * (i + 0.5));
for (i = 12; i < 36; i++)
win[2][i] = 0.0F;
/*--- invert signs by region to match mdct 18pt --> 36pt mapping */
for (j = 0; j < 4; j++)
{
if (j == 2)
continue;
for (i = 9; i < 36; i++)
win[j][i] = -win[j][i];
}
/*-- invert signs for short blocks --*/
for (i = 3; i < 12; i++)
win[2][i] = -win[2][i];
return;
}
/*====================================================================*/
int hybrid(float xin[], float xprev[], float y[18][32],
int btype, int nlong, int ntot, int nprev)
{
int i, j;
float *x, *x0;
float xa, xb;
int n;
int nout;
int band_limit_nsb;
if (btype == 2)
btype = 0;
x = xin;
x0 = xprev;
/*-- do long blocks (if any) --*/
n = (nlong + 17) / 18; /* number of dct's to do */
for (i = 0; i < n; i++)
{
imdct18(x);
for (j = 0; j < 9; j++)
{
y[j][i] = x0[j] + win[btype][j] * x[9 + j];
y[9 + j][i] = x0[9 + j] + win[btype][9 + j] * x[17 - j];
}
/* window x for next time x0 */
for (j = 0; j < 4; j++)
{
xa = x[j];
xb = x[8 - j];
x[j] = win[btype][18 + j] * xb;
x[8 - j] = win[btype][(18 + 8) - j] * xa;
x[9 + j] = win[btype][(18 + 9) + j] * xa;
x[17 - j] = win[btype][(18 + 17) - j] * xb;
}
xa = x[j];
x[j] = win[btype][18 + j] * xa;
x[9 + j] = win[btype][(18 + 9) + j] * xa;
x += 18;
x0 += 18;
}
/*-- do short blocks (if any) --*/
n = (ntot + 17) / 18; /* number of 6 pt dct's triples to do */
for (; i < n; i++)
{
imdct6_3(x);
for (j = 0; j < 3; j++)
{
y[j][i] = x0[j];
y[3 + j][i] = x0[3 + j];
y[6 + j][i] = x0[6 + j] + win[2][j] * x[3 + j];
y[9 + j][i] = x0[9 + j] + win[2][3 + j] * x[5 - j];
y[12 + j][i] = x0[12 + j] + win[2][6 + j] * x[2 - j] + win[2][j] * x[(6 + 3) + j];
y[15 + j][i] = x0[15 + j] + win[2][9 + j] * x[j] + win[2][3 + j] * x[(6 + 5) - j];
}
/* window x for next time x0 */
for (j = 0; j < 3; j++)
{
x[j] = win[2][6 + j] * x[(6 + 2) - j] + win[2][j] * x[(12 + 3) + j];
x[3 + j] = win[2][9 + j] * x[6 + j] + win[2][3 + j] * x[(12 + 5) - j];
}
for (j = 0; j < 3; j++)
{
x[6 + j] = win[2][6 + j] * x[(12 + 2) - j];
x[9 + j] = win[2][9 + j] * x[12 + j];
}
for (j = 0; j < 3; j++)
{
x[12 + j] = 0.0f;
x[15 + j] = 0.0f;
}
x += 18;
x0 += 18;
}
/*--- overlap prev if prev longer that current --*/
n = (nprev + 17) / 18;
for (; i < n; i++)
{
for (j = 0; j < 18; j++)
y[j][i] = x0[j];
x0 += 18;
}
nout = 18 * i;
/*--- clear remaining only to band limit --*/
band_limit_nsb = (m_band_limit + 17) / 18; /* limit nsb's rounded up */
for (; i < band_limit_nsb; i++)
{
for (j = 0; j < 18; j++)
y[j][i] = 0.0f;
}
return nout;
}
/*--------------------------------------------------------------------*/
/*--------------------------------------------------------------------*/
/*-- convert to mono, add curr result to y,
window and add next time to current left */
int hybrid_sum(float xin[], float xin_left[], float y[18][32],
int btype, int nlong, int ntot)
{
int i, j;
float *x, *x0;
float xa, xb;
int n;
int nout;
if (btype == 2)
btype = 0;
x = xin;
x0 = xin_left;
/*-- do long blocks (if any) --*/
n = (nlong + 17) / 18; /* number of dct's to do */
for (i = 0; i < n; i++)
{
imdct18(x);
for (j = 0; j < 9; j++)
{
y[j][i] += win[btype][j] * x[9 + j];
y[9 + j][i] += win[btype][9 + j] * x[17 - j];
}
/* window x for next time x0 */
for (j = 0; j < 4; j++)
{
xa = x[j];
xb = x[8 - j];
x0[j] += win[btype][18 + j] * xb;
x0[8 - j] += win[btype][(18 + 8) - j] * xa;
x0[9 + j] += win[btype][(18 + 9) + j] * xa;
x0[17 - j] += win[btype][(18 + 17) - j] * xb;
}
xa = x[j];
x0[j] += win[btype][18 + j] * xa;
x0[9 + j] += win[btype][(18 + 9) + j] * xa;
x += 18;
x0 += 18;
}
/*-- do short blocks (if any) --*/
n = (ntot + 17) / 18; /* number of 6 pt dct's triples to do */
for (; i < n; i++)
{
imdct6_3(x);
for (j = 0; j < 3; j++)
{
y[6 + j][i] += win[2][j] * x[3 + j];
y[9 + j][i] += win[2][3 + j] * x[5 - j];
y[12 + j][i] += win[2][6 + j] * x[2 - j] + win[2][j] * x[(6 + 3) + j];
y[15 + j][i] += win[2][9 + j] * x[j] + win[2][3 + j] * x[(6 + 5) - j];
}
/* window x for next time */
for (j = 0; j < 3; j++)
{
x0[j] += win[2][6 + j] * x[(6 + 2) - j] + win[2][j] * x[(12 + 3) + j];
x0[3 + j] += win[2][9 + j] * x[6 + j] + win[2][3 + j] * x[(12 + 5) - j];
}
for (j = 0; j < 3; j++)
{
x0[6 + j] += win[2][6 + j] * x[(12 + 2) - j];
x0[9 + j] += win[2][9 + j] * x[12 + j];
}
x += 18;
x0 += 18;
}
nout = 18 * i;
return nout;
}
/*--------------------------------------------------------------------*/
void sum_f_bands(float a[], float b[], int n)
{
int i;
for (i = 0; i < n; i++)
a[i] += b[i];
}
/*--------------------------------------------------------------------*/
void freq_invert(float y[18][32], int n)
{
int i, j;
n = (n + 17) / 18;
for (j = 0; j < 18; j += 2)
{
for (i = 0; i < n; i += 2)
{
y[1 + j][1 + i] = -y[1 + j][1 + i];
}
}
}
/*--------------------------------------------------------------------*/