newmdct.c

音频编码

  {
    1.316524975873958e-01, /* win[SHORT_TYPE] */
    4.142135623730950e-01,
    7.673269879789602e-01,

    1.091308501069271e+00, /* tantab_l */
    1.303225372841206e+00,
    1.569685577117490e+00,
    1.920982126971166e+00,
    2.414213562373094e+00,
    3.171594802363212e+00,
    4.510708503662055e+00,
    7.595754112725146e+00,
    2.290376554843115e+01,

    0.98480775301220802032, /* cx */
    0.64278760968653936292,
    0.34202014332566882393,
    0.93969262078590842791,
    -0.17364817766693030343,
    -0.76604444311897790243,
    0.86602540378443870761,
    0.500000000000000e+00,

    -5.144957554275265e-01, /* ca */
    -4.717319685649723e-01,
    -3.133774542039019e-01,
    -1.819131996109812e-01,
    -9.457419252642064e-02,
    -4.096558288530405e-02,
    -1.419856857247115e-02,
    -3.699974673760037e-03,

     8.574929257125442e-01, /* cs */
     8.817419973177052e-01,
     9.496286491027329e-01,
     9.833145924917901e-01,
     9.955178160675857e-01,
     9.991605581781475e-01,
     9.998991952444470e-01,
     9.999931550702802e-01,
  },
  {
    0.000000000000000e+00,
    0.000000000000000e+00,
    0.000000000000000e+00,
    0.000000000000000e+00,
    0.000000000000000e+00,
    0.000000000000000e+00,
    2.283748241799531e-13,
    4.037858874020686e-13,
    2.146547464825323e-13,

    5.461314069809755e-12,
    4.921085770524055e-12,
    4.343405037091838e-12,
    3.732668368707687e-12,
    3.093523840190885e-12,
    2.430835727329466e-12,
    1.734679010007751e-12,
    9.748253656609281e-13,
    2.797435120168326e-13,

    -5.456116108943413e-12,
    -4.878985199565852e-12,
    -4.240448995017367e-12,
    -3.559909094758253e-12,
    -2.858043359288075e-12,
    -2.156177623817898e-12,
    -1.475637723558782e-12,
    -8.371015190102975e-13,
    -2.599706096327376e-13,

    -2.382191739347913e-13,
    -6.423305872147834e-13,
    -9.400849094049688e-13,
    -1.122435026096556e-12,
    -1.183840321267481e-12,
    -1.122435026096556e-12,
    -9.400849094049688e-13,
    -6.423305872147841e-13,
    -2.382191739347918e-13,
  }
};

#define tantab_l (win[SHORT_TYPE]+3)
#define cx (win[SHORT_TYPE]+12)
#define ca (win[SHORT_TYPE]+20)
#define cs (win[SHORT_TYPE]+28)

/************************************************************************
*
* window_subband()
*
* PURPOSE:  Overlapping window on PCM samples
*
* SEMANTICS:
* 32 16-bit pcm samples are scaled to fractional 2's complement and
* concatenated to the end of the window buffer #x#. The updated window
* buffer #x# is then windowed by the analysis window #c# to produce the
* windowed sample #z#
*
************************************************************************/

/*
 *      new IDCT routine written by Takehiro TOMINAGA
 */
static const int order[] = {
  0, 1,16,17, 8, 9,24,25, 4, 5,20,21,12,13,28,29,
  2, 3,18,19,10,11,26,27, 6, 7,22,23,14,15,30,31
};


/* returns sum_j=0^31 a[j]*cos(PI*j*(k+1/2)/32), 0<=k<32 */
inline static void
window_subband(const sample_t *x1, FLOAT a[SBLIMIT])
{
    int i;
    FLOAT const *wp = enwindow+10;

    const sample_t *x2 = &x1[238-14-286];

    for (i = -15; i < 0; i++) {
	FLOAT w, s, t;

	w = wp[-10]; s = x2[-224] * w; t  = x1[ 224] * w;
	w = wp[-9]; s += x2[-160] * w; t += x1[ 160] * w;
	w = wp[-8]; s += x2[- 96] * w; t += x1[  96] * w;
	w = wp[-7]; s += x2[- 32] * w; t += x1[  32] * w;
	w = wp[-6]; s += x2[  32] * w; t += x1[- 32] * w;
	w = wp[-5]; s += x2[  96] * w; t += x1[- 96] * w;
	w = wp[-4]; s += x2[ 160] * w; t += x1[-160] * w;
	w = wp[-3]; s += x2[ 224] * w; t += x1[-224] * w;

	w = wp[-2]; s += x1[-256] * w; t -= x2[ 256] * w;
	w = wp[-1]; s += x1[-192] * w; t -= x2[ 192] * w;
	w = wp[ 0]; s += x1[-128] * w; t -= x2[ 128] * w;
	w = wp[ 1]; s += x1[- 64] * w; t -= x2[  64] * w;
	w = wp[ 2]; s += x1[   0] * w; t -= x2[   0] * w;
	w = wp[ 3]; s += x1[  64] * w; t -= x2[- 64] * w;
	w = wp[ 4]; s += x1[ 128] * w; t -= x2[-128] * w;
	w = wp[ 5]; s += x1[ 192] * w; t -= x2[-192] * w;

	/*
	 * this multiplyer could be removed, but it needs more 256 FLOAT data.
	 * thinking about the data cache performance, I think we should not
	 * use such a huge table. tt 2000/Oct/25
	 */
	s *= wp[6];
	w = t - s;
	a[30+i*2] = t + s;
	a[31+i*2] = wp[7] * w;
	wp += 18;
	x1--;
	x2++;
    }
    {
	FLOAT s,t,u,v;
	t  =  x1[- 16] * wp[-10];              s  = x1[ -32] * wp[-2];
	t += (x1[- 48] - x1[ 16]) * wp[-9];    s += x1[ -96] * wp[-1];
	t += (x1[- 80] + x1[ 48]) * wp[-8];    s += x1[-160] * wp[ 0];
	t += (x1[-112] - x1[ 80]) * wp[-7];    s += x1[-224] * wp[ 1];
	t += (x1[-144] + x1[112]) * wp[-6];    s -= x1[  32] * wp[ 2];
	t += (x1[-176] - x1[144]) * wp[-5];    s -= x1[  96] * wp[ 3];
	t += (x1[-208] + x1[176]) * wp[-4];    s -= x1[ 160] * wp[ 4];
	t += (x1[-240] - x1[208]) * wp[-3];    s -= x1[ 224];

	u = s - t;
	v = s + t;

	t = a[14];
	s = a[15] - t;

	a[31] = v + t;   /* A0 */
	a[30] = u + s;   /* A1 */
	a[15] = u - s;   /* A2 */
	a[14] = v - t;   /* A3 */
    }
{
    FLOAT xr;
    xr = a[28] - a[ 0]; a[ 0] += a[28]; a[28] = xr * wp[-2*18+7];
    xr = a[29] - a[ 1]; a[ 1] += a[29]; a[29] = xr * wp[-2*18+7];

    xr = a[26] - a[ 2]; a[ 2] += a[26]; a[26] = xr * wp[-4*18+7];
    xr = a[27] - a[ 3]; a[ 3] += a[27]; a[27] = xr * wp[-4*18+7];

    xr = a[24] - a[ 4]; a[ 4] += a[24]; a[24] = xr * wp[-6*18+7];
    xr = a[25] - a[ 5]; a[ 5] += a[25]; a[25] = xr * wp[-6*18+7];

    xr = a[22] - a[ 6]; a[ 6] += a[22]; a[22] = xr * SQRT2;
    xr = a[23] - a[ 7]; a[ 7] += a[23]; a[23] = xr * SQRT2 - a[ 7];
    a[ 7] -= a[ 6];
    a[22] -= a[ 7];
    a[23] -= a[22];

    xr = a[ 6]; a[ 6] = a[31] - xr; a[31] = a[31] + xr;
    xr = a[ 7]; a[ 7] = a[30] - xr; a[30] = a[30] + xr;
    xr = a[22]; a[22] = a[15] - xr; a[15] = a[15] + xr;
    xr = a[23]; a[23] = a[14] - xr; a[14] = a[14] + xr;

    xr = a[20] - a[ 8]; a[ 8] += a[20]; a[20] = xr * wp[-10*18+7];
    xr = a[21] - a[ 9]; a[ 9] += a[21]; a[21] = xr * wp[-10*18+7];

    xr = a[18] - a[10]; a[10] += a[18]; a[18] = xr * wp[-12*18+7];
    xr = a[19] - a[11]; a[11] += a[19]; a[19] = xr * wp[-12*18+7];

    xr = a[16] - a[12]; a[12] += a[16]; a[16] = xr * wp[-14*18+7];
    xr = a[17] - a[13]; a[13] += a[17]; a[17] = xr * wp[-14*18+7];

    xr = -a[20] + a[24]; a[20] += a[24]; a[24] = xr * wp[-12*18+7];
    xr = -a[21] + a[25]; a[21] += a[25]; a[25] = xr * wp[-12*18+7];

    xr = a[ 4] - a[ 8]; a[ 4] += a[ 8]; a[ 8] = xr * wp[-12*18+7];
    xr = a[ 5] - a[ 9]; a[ 5] += a[ 9]; a[ 9] = xr * wp[-12*18+7];

    xr = a[ 0] - a[12]; a[ 0] += a[12]; a[12] = xr * wp[-4*18+7];
    xr = a[ 1] - a[13]; a[ 1] += a[13]; a[13] = xr * wp[-4*18+7];
    xr = a[16] - a[28]; a[16] += a[28]; a[28] = xr * wp[-4*18+7];
    xr = -a[17] + a[29]; a[17] += a[29]; a[29] = xr * wp[-4*18+7];

    xr = SQRT2 * (a[ 2] - a[10]); a[ 2] += a[10]; a[10] = xr;
    xr = SQRT2 * (a[ 3] - a[11]); a[ 3] += a[11]; a[11] = xr;
    xr = SQRT2 * (-a[18] + a[26]); a[18] += a[26]; a[26] = xr - a[18];
    xr = SQRT2 * (-a[19] + a[27]); a[19] += a[27]; a[27] = xr - a[19];

    xr = a[ 2]; a[19] -= a[ 3]; a[ 3] -= xr; a[ 2] = a[31] - xr; a[31] += xr;
    xr = a[ 3]; a[11] -= a[19]; a[18] -= xr; a[ 3] = a[30] - xr; a[30] += xr;
    xr = a[18]; a[27] -= a[11]; a[19] -= xr; a[18] = a[15] - xr; a[15] += xr;

    xr = a[19]; a[10] -= xr; a[19] = a[14] - xr; a[14] += xr;
    xr = a[10]; a[11] -= xr; a[10] = a[23] - xr; a[23] += xr;
    xr = a[11]; a[26] -= xr; a[11] = a[22] - xr; a[22] += xr;
    xr = a[26]; a[27] -= xr; a[26] = a[ 7] - xr; a[ 7] += xr;

    xr = a[27]; a[27] = a[ 6] - xr; a[ 6] += xr;

    xr = SQRT2 * (a[ 0] - a[ 4]); a[ 0] += a[ 4]; a[ 4] = xr;
    xr = SQRT2 * (a[ 1] - a[ 5]); a[ 1] += a[ 5]; a[ 5] = xr;
    xr = SQRT2 * (a[16] - a[20]); a[16] += a[20]; a[20] = xr;
    xr = SQRT2 * (a[17] - a[21]); a[17] += a[21]; a[21] = xr;

    xr = -SQRT2 * (a[ 8] - a[12]); a[ 8] += a[12]; a[12] = xr - a[ 8];
    xr = -SQRT2 * (a[ 9] - a[13]); a[ 9] += a[13]; a[13] = xr - a[ 9];
    xr = -SQRT2 * (a[25] - a[29]); a[25] += a[29]; a[29] = xr - a[25];
    xr = -SQRT2 * (a[24] + a[28]); a[24] -= a[28]; a[28] = xr - a[24];

    xr = a[24] - a[16]; a[24] = xr;
    xr = a[20] - xr;    a[20] = xr;
    xr = a[28] - xr;    a[28] = xr;

    xr = a[25] - a[17]; a[25] = xr;
    xr = a[21] - xr;    a[21] = xr;
    xr = a[29] - xr;    a[29] = xr;

    xr = a[17] - a[ 1]; a[17] = xr;
    xr = a[ 9] - xr;    a[ 9] = xr;
    xr = a[25] - xr;    a[25] = xr;
    xr = a[ 5] - xr;    a[ 5] = xr;
    xr = a[21] - xr;    a[21] = xr;
    xr = a[13] - xr;    a[13] = xr;