--- /dev/null
+/*\r
+ * 11/19/04 1.0 moved to LGPL.\r
+ * 12/12/99 Initial version. mdm@techie.com\r
+ *-----------------------------------------------------------------------\r
+ * This program is free software; you can redistribute it and/or modify\r
+ * it under the terms of the GNU Library General Public License as published\r
+ * by the Free Software Foundation; either version 2 of the License, or\r
+ * (at your option) any later version.\r
+ *\r
+ * This program is distributed in the hope that it will be useful,\r
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of\r
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the\r
+ * GNU Library General Public License for more details.\r
+ *\r
+ * You should have received a copy of the GNU Library General Public\r
+ * License along with this program; if not, write to the Free Software\r
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.\r
+ *----------------------------------------------------------------------\r
+ */\r
+\r
+/**\r
+ * The <code>Equalizer</code> class can be used to specify equalization settings\r
+ * for the MPEG audio decoder.\r
+ * <p>\r
+ * The equalizer consists of 32 band-pass filters. Each band of the equalizer\r
+ * can take on a fractional value between -1.0 and +1.0. At -1.0, the input\r
+ * signal is attenuated by 6dB, at +1.0 the signal is amplified by 6dB.\r
+ * \r
+ * @see Decoder\r
+ * \r
+ * @author MDM\r
+ */\r
+\r
+\r
+public final class Equalizer {\r
+ /**\r
+ * Equalizer setting to denote that a given band will not be present in the\r
+ * output signal.\r
+ */\r
+ \r
+ static public final float BAND_NOT_PRESENT = Float.NEGATIVE_INFINITY;\r
+\r
+ \r
+ static public final Equalizer PASS_THRU_EQ = new Equalizer();\r
+\r
+ \r
+ private static final int BANDS = 32;\r
+\r
+ \r
+ private final float[] settings = new float[BANDS];\r
+\r
+ /**\r
+ * Creates a new <code>Equalizer</code> instance.\r
+ */\r
+ public Equalizer() {\r
+ }\r
+\r
+ // private Equalizer(float b1, float b2, float b3, float b4, float b5,\r
+ // float b6, float b7, float b8, float b9, float b10, float b11,\r
+ // float b12, float b13, float b14, float b15, float b16,\r
+ // float b17, float b18, float b19, float b20);\r
+\r
+ public Equalizer(float[] settings) {\r
+ setFrom(settings);\r
+ }\r
+\r
+ public Equalizer(EQFunction eq) {\r
+ setFrom(eq);\r
+ }\r
+\r
+ public void setFrom(float[] eq) {\r
+ reset();\r
+ int max = (eq.length > BANDS) ? BANDS : eq.length;\r
+\r
+ for (int i = 0; i < max; i++) {\r
+ settings[i] = limit(eq[i]);\r
+ }\r
+ }\r
+\r
+ public void setFrom(EQFunction eq) {\r
+ reset();\r
+ int max = BANDS;\r
+\r
+ for (int i = 0; i < max; i++) {\r
+ settings[i] = limit(eq.getBand(i));\r
+ }\r
+ }\r
+\r
+ /**\r
+ * Sets the bands of this equalizer to the value the bands of another\r
+ * equalizer. Bands that are not present in both equalizers are ignored.\r
+ */\r
+ public void setFrom(Equalizer eq) {\r
+ if (eq != this) {\r
+ setFrom(eq.settings);\r
+ }\r
+ }\r
+\r
+ /**\r
+ * Sets all bands to 0.0\r
+ */\r
+ public void reset() {\r
+ for (int i = 0; i < BANDS; i++) {\r
+ settings[i] = 0.0f;\r
+ }\r
+ }\r
+\r
+ /**\r
+ * Retrieves the number of bands present in this equalizer.\r
+ */\r
+ public int getBandCount() {\r
+ return settings.length;\r
+ }\r
+\r
+ public float setBand(int band, float neweq) {\r
+ float eq = 0.0f;\r
+\r
+ if ((band >= 0) && (band < BANDS)) {\r
+ eq = settings[band];\r
+ settings[band] = limit(neweq);\r
+ }\r
+\r
+ return eq;\r
+ }\r
+\r
+ /**\r
+ * Retrieves the eq setting for a given band.\r
+ */\r
+ public float getBand(int band) {\r
+ float eq = 0.0f;\r
+\r
+ if ((band >= 0) && (band < BANDS)) {\r
+ eq = settings[band];\r
+ }\r
+\r
+ return eq;\r
+ }\r
+\r
+ private float limit(float eq) {\r
+ if (eq == BAND_NOT_PRESENT)\r
+ return eq;\r
+ if (eq > 1.0f)\r
+ return 1.0f;\r
+ if (eq < -1.0f)\r
+ return -1.0f;\r
+\r
+ return eq;\r
+ }\r
+\r
+ /**\r
+ * Retrieves an array of floats whose values represent a scaling factor that\r
+ * can be applied to linear samples in each band to provide the equalization\r
+ * represented by this instance.\r
+ * \r
+ * @return an array of factors that can be applied to the subbands.\r
+ */\r
+ \r
+ \r
+ float[] getBandFactors() {\r
+ float[] factors = new float[BANDS];\r
+ int maxCount = BANDS;\r
+ for ( int i = 0; i < maxCount; i++) {\r
+ factors[i] = getBandFactor(settings[i]);\r
+ }\r
+\r
+ return factors;\r
+ }\r
+\r
+ /**\r
+ * Converts an equalizer band setting to a sample factor. The factor is\r
+ * determined by the function f = 2^n where n is the equalizer band setting in\r
+ * the range [-1.0,1.0].\r
+ * \r
+ */\r
+ \r
+ float getBandFactor( float eq) {\r
+ if (eq == BAND_NOT_PRESENT)\r
+ return 0.0f;\r
+\r
+ float f = (float) Math.pow(2.0, eq);\r
+ return f;\r
+ }\r
+\r
+ static abstract public class EQFunction {\r
+ /**\r
+ * Returns the setting of a band in the equalizer.\r
+ * \r
+ * @param band\r
+ * The index of the band to retrieve the setting for.\r
+ * \r
+ * @return the setting of the specified band. This is a value between -1 and\r
+ * +1.\r
+ */\r
+ public float getBand(int band) {\r
+ return 0.0f;\r
+ }\r
+\r
+ }\r
+\r
+}\r
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