Songdb java version, source. only 1.5 compatible

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7101 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 227 insertions, 0 deletions

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