ref: 621a7161f019e342012ce33c00273bc143cea687
parent: a406642c783fc7d3bbbb1531f1e309e98008de96
author: menno <menno>
date: Fri Jan 19 09:58:41 EST 2001
Changed ATH formula
--- a/libfaac/psych.c
+++ b/libfaac/psych.c
@@ -16,7 +16,7 @@
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
- * $Id: psych.c,v 1.1 2001/01/17 11:21:40 menno Exp $
+ * $Id: psych.c,v 1.2 2001/01/19 14:58:41 menno Exp $
*/
#include <stdlib.h>
@@ -1172,53 +1172,17 @@
return (bark);
}
-static double ATHformula(double freq)
+static double ATHformula(double f)
{- /* short [MilliBel] is also sufficient */
- static double tab [] = {- /* 10.0 */ 96.69, 96.69, 96.26, 95.12,
- /* 12.6 */ 93.53, 91.13, 88.82, 86.76,
- /* 15.8 */ 84.69, 82.43, 79.97, 77.48,
- /* 20.0 */ 74.92, 72.39, 70.00, 67.62,
- /* 25.1 */ 65.29, 63.02, 60.84, 59.00,
- /* 31.6 */ 57.17, 55.34, 53.51, 51.67,
- /* 39.8 */ 50.04, 48.12, 46.38, 44.66,
- /* 50.1 */ 43.10, 41.73, 40.50, 39.22,
- /* 63.1 */ 37.23, 35.77, 34.51, 32.81,
- /* 79.4 */ 31.32, 30.36, 29.02, 27.60,
- /* 100.0 */ 26.58, 25.91, 24.41, 23.01,
- /* 125.9 */ 22.12, 21.25, 20.18, 19.00,
- /* 158.5 */ 17.70, 16.82, 15.94, 15.12,
- /* 199.5 */ 14.30, 13.41, 12.60, 11.98,
- /* 251.2 */ 11.36, 10.57, 9.98, 9.43,
- /* 316.2 */ 8.87, 8.46, 7.44, 7.12,
- /* 398.1 */ 6.93, 6.68, 6.37, 6.06,
- /* 501.2 */ 5.80, 5.55, 5.29, 5.02,
- /* 631.0 */ 4.75, 4.48, 4.22, 3.98,
- /* 794.3 */ 3.75, 3.51, 3.27, 3.22,
- /* 1000.0 */ 3.12, 3.01, 2.91, 2.68,
- /* 1258.9 */ 2.46, 2.15, 1.82, 1.46,
- /* 1584.9 */ 1.07, 0.61, 0.13, -0.35,
- /* 1995.3 */ -0.96, -1.56, -1.79, -2.35,
- /* 2511.9 */ -2.95, -3.50, -4.01, -4.21,
- /* 3162.3 */ -4.46, -4.99, -5.32, -5.35,
- /* 3981.1 */ -5.13, -4.76, -4.31, -3.13,
- /* 5011.9 */ -1.79, 0.08, 2.03, 4.03,
- /* 6309.6 */ 5.80, 7.36, 8.81, 10.22,
- /* 7943.3 */ 11.54, 12.51, 13.48, 14.21,
- /* 10000.0 */ 14.79, 13.99, 12.85, 11.93,
- /* 12589.3 */ 12.87, 15.19, 19.14, 23.69,
- /* 15848.9 */ 33.52, 48.65, 59.42, 61.77,
- /* 19952.6 */ 63.85, 66.04, 68.33, 70.09,
- /* 25118.9 */ 70.66, 71.27, 71.91, 72.60,
- };
- double freq_log;
- unsigned index;
+ double ath;
+ f /= 1000; // convert to khz
+ f = max(0.01, f);
+ f = min(18.0,f);
- if ( freq < 10. ) freq = 10.;
- if ( freq > 25000. ) freq = 25000.;
-
- freq_log = 40. * log10 (0.1 * freq); /* 4 steps per third, starting at 10 Hz */
- index = (unsigned) freq_log;
- return tab [index] * (1 + index - freq_log) + tab [index+1] * (freq_log - index);
+ /* from Painter & Spanias, 1997 */
+ /* minimum: (i=77) 3.3kHz = -5db */
+ ath = 3.640 * pow(f,-0.8)
+ - 6.500 * exp(-0.6*pow(f-3.3,2.0))
+ + 0.001 * pow(f,4.0);
+ return ath;
}