From d34041569e71fc9bd772354e94dc9d16061072a5 Mon Sep 17 00:00:00 2001
From: arpi_esp <arpi_esp@b3059339-0415-0410-9bf9-f77b7e298cf2>
Date: Sat, 24 Feb 2001 20:28:24 +0000
Subject: Initial revision

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@2 b3059339-0415-0410-9bf9-f77b7e298cf2
---
 mp3lib/equalizer.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 mp3lib/equalizer.c

(limited to 'mp3lib/equalizer.c')

diff --git a/mp3lib/equalizer.c b/mp3lib/equalizer.c
new file mode 100644
index 0000000000..acb5bc18e0
--- /dev/null
+++ b/mp3lib/equalizer.c
@@ -0,0 +1,79 @@
+#include "mpg123.h"
+
+void init_spline(float *x, float *y, int n, float *y2)
+{
+
+	int i, k;
+	float p, qn, sig, un, *u;
+	u = (float *) malloc(n * sizeof (float));
+
+	y2[0] = u[0] = 0.0;
+
+	for (i = 1; i < n - 1; i++)
+	{
+		sig = ((float) x[i] - x[i - 1]) / ((float) x[i + 1] - x[i - 1]);
+		p = sig * y2[i - 1] + 2.0;
+		y2[i] = (sig - 1.0) / p;
+		u[i] = (((float) y[i + 1] - y[i]) / (x[i + 1] - x[i])) -
+			(((float) y[i] - y[i - 1]) / (x[i] - x[i - 1]));
+		u[i] = (6.0 * u[i] / (x[i + 1] - x[i - 1]) - sig * u[i - 1]) / p;
+	}
+	qn = un = 0.0;
+
+	y2[n - 1] = (un - qn * u[n - 2]) / (qn * y2[n - 2] + 1.0);
+	for (k = n - 2; k >= 0; k--)
+		y2[k] = y2[k] * y2[k + 1] + u[k];
+	free(u);
+}
+
+float eval_spline(float xa[], float ya[], float y2a[], int n, float x)
+{
+	int klo, khi, k;
+	float h, b, a;
+
+	klo = 0;
+	khi = n - 1;
+	while (khi - klo > 1)
+	{
+		k = (khi + klo) >> 1;
+		if (xa[k] > x)
+			khi = k;
+		else
+			klo = k;
+	}
+	h = xa[khi] - xa[klo];
+	a = (xa[khi] - x) / h;
+	b = (x - xa[klo]) / h;
+	return (a * ya[klo] + b * ya[khi] + ((a * a * a - a) * y2a[klo] + (b * b * b - b) * y2a[khi])
+		* (h * h) / 6.0);
+}
+
+void mpg123_set_eq(int on, float preamp, float *b)
+{
+	float x[] =
+	{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, yf[10], val, band[10];
+	int bands[] =
+	{0, 4, 8, 16, 26, 78, 157, 313, 366, 418};
+	int i, j;
+
+	mpg123_info->eq_active = on;
+	if (mpg123_info->eq_active)
+	{
+		for (i = 0; i < 10; i++)
+		{
+			band[i] = b[i] + preamp;
+		}
+
+		init_spline(x, band, 10, yf);
+		for (i = 0; i < 9; i++)
+		{
+			for (j = bands[i]; j < bands[i + 1]; j++)
+			{
+				val = eval_spline(x, band, yf, 10, i + ((float) (j - bands[i]) * (1.0 / (bands[i + 1] - bands[i]))));
+				mpg123_info->eq_mul[j] = pow(2, val / 10.0);
+			}
+		}
+		for (i = bands[9]; i < 576; i++)
+			mpg123_info->eq_mul[i] = mpg123_info->eq_mul[bands[9] - 1];
+	}
+}
-- 
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