InbandGeneratorImpl.java

/*
 * Mobicents, Communications Middleware
 * 
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party
 * contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * for more details.
 *
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 *
 * Boston, MA  02110-1301  USA
 */
package org.mobicents.media.server.impl.resource.dtmf;


import org.mobicents.media.Buffer;
import org.mobicents.media.Format;
import org.mobicents.media.format.AudioFormat;
import org.mobicents.media.server.impl.AbstractSource;
import org.mobicents.media.server.spi.SyncSource;
import org.mobicents.media.server.spi.dsp.Codec;
import org.mobicents.media.server.spi.resource.DtmfGenerator;

/**
 * InbandGenerator generates Inband DTMF Tone only for uncompressed LINEAR
 * codec. After creating instance of InbandGenerator, it needs to be initialized
 * so that all the Tones are generated and kept ready for transmission once
 * start is called.
 * 
 * By default the Tone duration is 80ms. This is suited for Tone Detector who
 * has Tone duration of greater than 40 and less than 80ms. For Tone Detector
 * who's Tone duration is set greater than 80ms may fail to detect Tone
 * generated by InbandGenerator(with duration 80ms). In that case increase the
 * duration here too.
 * 
 * @author Oleg Kulikov
 * @author amit bhayani
 */
public class InbandGeneratorImpl extends AbstractSource implements DtmfGenerator {

    private final static AudioFormat LINEAR_AUDIO = new AudioFormat(
            AudioFormat.LINEAR, 8000, 16, 1,
            AudioFormat.LITTLE_ENDIAN,
            AudioFormat.SIGNED);
    
    public final static String[][] events = new String[][]{
        {"1", "2", "3", "A"}, 
        {"4", "5", "6", "B"},
        {"7", "8", "9", "C"}, 
        {"*", "0", "#", "D"}
    };
    
    private int[] lowFreq = new int[]{697, 770, 852, 941};
    private int[] highFreq = new int[]{1209, 1336, 1477, 1633};
        
    private String digit = null;    // Min duration = 40ms and max = 500ms
    private int duration = 50;    

    private short A = Short.MAX_VALUE/2;
    private int volume = 0;
    
    private int f1, f2;
    
    private double dt;
    private int pSize;
    
    private double time = 0;
    
    public InbandGeneratorImpl(String name, SyncSource syncSource) {
        super(name);
        setSyncSource(syncSource);
        dt = 1/LINEAR_AUDIO.getSampleRate();
    }


    public void setDigit(String digit) {
        this.digit = digit;
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                if (events[i][j].equalsIgnoreCase(digit)) {
                    f1 = lowFreq[i];
                    f2 = highFreq[j];
                }
            }
        }
    }

    public String getDigit() {
        return this.digit;
    }

    public void setToneDuration(int duration) {
        if (duration < 40) {
            throw new IllegalArgumentException("Duration cannot be less than 40ms");
        }
        this.duration = duration;
    }

    public int getToneDuration() {
        return duration;
    }

    public int getVolume() {
        return this.volume;
    }

    public void setVolume(int volume) {
        if (volume > 0) {
            throw new IllegalArgumentException("Volume has to be negative value expressed in dBm0");
        }
        this.volume = volume;
        A = (short)(Math.pow(Math.pow(10, volume), 0.1) * (Short.MAX_VALUE / 2));
    }

    private short getValue(double t) {
        return (short) (A* (Math.sin(2 * Math.PI * f1 * t) + Math.sin(2*Math.PI * f2 * t)));
    }
    
    public Format getFormat() {
        return Codec.LINEAR_AUDIO;
    }

    public Format[] getFormats() {
        return new Format[] {LINEAR_AUDIO};
    }

    @Override
    public void evolve(Buffer buffer, long timestamp, long seq) {
        byte[] data = (byte[])buffer.getData();
        
        int k = 0;
        
        pSize = (int)((double)getDuration()/1000.0/dt);
        for (int i = 0; i < pSize; i++) {
            short v = getValue(time + dt * i);
            data[k++] = (byte) v;
            data[k++] = (byte) (v >> 8);
        }
        
        buffer.setFormat(LINEAR_AUDIO);
        buffer.setSequenceNumber(seq);
        buffer.setTimeStamp(getSyncSource().getTimestamp());
        buffer.setDuration(getDuration());
        buffer.setOffset(0);
        buffer.setLength(2*pSize);
        
        time += ((double)getDuration())/1000.0;
        buffer.setEOM(time > (double)duration/1000.0);
    }
    
    @Override
    public void stop() {
    }
}