mirror of
https://github.com/mpv-player/mpv
synced 2024-11-18 21:16:10 +01:00
80 lines
1.8 KiB
C
80 lines
1.8 KiB
C
#include "mpg123.h"
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void init_spline(float *x, float *y, int n, float *y2)
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{
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int i, k;
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float p, qn, sig, un, *u;
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u = (float *) malloc(n * sizeof (float));
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y2[0] = u[0] = 0.0;
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for (i = 1; i < n - 1; i++)
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{
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sig = ((float) x[i] - x[i - 1]) / ((float) x[i + 1] - x[i - 1]);
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p = sig * y2[i - 1] + 2.0;
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y2[i] = (sig - 1.0) / p;
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u[i] = (((float) y[i + 1] - y[i]) / (x[i + 1] - x[i])) -
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(((float) y[i] - y[i - 1]) / (x[i] - x[i - 1]));
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u[i] = (6.0 * u[i] / (x[i + 1] - x[i - 1]) - sig * u[i - 1]) / p;
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}
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qn = un = 0.0;
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y2[n - 1] = (un - qn * u[n - 2]) / (qn * y2[n - 2] + 1.0);
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for (k = n - 2; k >= 0; k--)
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y2[k] = y2[k] * y2[k + 1] + u[k];
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free(u);
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}
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float eval_spline(float xa[], float ya[], float y2a[], int n, float x)
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{
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int klo, khi, k;
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float h, b, a;
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klo = 0;
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khi = n - 1;
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while (khi - klo > 1)
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{
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k = (khi + klo) >> 1;
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if (xa[k] > x)
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khi = k;
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else
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klo = k;
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}
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h = xa[khi] - xa[klo];
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a = (xa[khi] - x) / h;
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b = (x - xa[klo]) / h;
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return (a * ya[klo] + b * ya[khi] + ((a * a * a - a) * y2a[klo] + (b * b * b - b) * y2a[khi])
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* (h * h) / 6.0);
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}
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void mpg123_set_eq(int on, float preamp, float *b)
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{
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float x[] =
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{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, yf[10], val, band[10];
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int bands[] =
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{0, 4, 8, 16, 26, 78, 157, 313, 366, 418};
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int i, j;
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mpg123_info->eq_active = on;
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if (mpg123_info->eq_active)
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{
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for (i = 0; i < 10; i++)
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{
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band[i] = b[i] + preamp;
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}
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init_spline(x, band, 10, yf);
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for (i = 0; i < 9; i++)
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{
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for (j = bands[i]; j < bands[i + 1]; j++)
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{
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val = eval_spline(x, band, yf, 10, i + ((float) (j - bands[i]) * (1.0 / (bands[i + 1] - bands[i]))));
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mpg123_info->eq_mul[j] = pow(2, val / 10.0);
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}
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}
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for (i = bands[9]; i < 576; i++)
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mpg123_info->eq_mul[i] = mpg123_info->eq_mul[bands[9] - 1];
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}
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}
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