-
- /* compute mdct windows */
- for (i = 0; i < 36; i++) {
- for (j = 0; j < 4; j++) {
- double d;
-
- if (j == 2 && i % 3 != 1)
- continue;
-
- d = sin(M_PI * (i + 0.5) / 36.0);
- if (j == 1) {
- if (i >= 30) d = 0;
- else if (i >= 24) d = sin(M_PI * (i - 18 + 0.5) / 12.0);
- else if (i >= 18) d = 1;
- } else if (j == 3) {
- if (i < 6) d = 0;
- else if (i < 12) d = sin(M_PI * (i - 6 + 0.5) / 12.0);
- else if (i < 18) d = 1;
- }
- //merge last stage of imdct into the window coefficients
- d *= 0.5 / cos(M_PI * (2 * i + 19) / 72);
-
- if (j == 2)
- mdct_win[j][i/3] = FIXHR((d / (1<<5)));
- else {
- int idx = i < 18 ? i : i + 2;
- mdct_win[j][idx] = FIXHR((d / (1<<5)));
- }
- }
- }
-
- /* NOTE: we do frequency inversion adter the MDCT by changing
- the sign of the right window coefs */
- for (j = 0; j < 4; j++) {
- for (i = 0; i < 40; i += 2) {
- mdct_win[j + 4][i ] = mdct_win[j][i ];
- mdct_win[j + 4][i + 1] = -mdct_win[j][i + 1];
- }
- }