MeanderDetector.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.test;

import java.io.IOException;
import org.mobicents.media.Buffer;
import org.mobicents.media.Format;
import org.mobicents.media.server.impl.AbstractSink;
import org.mobicents.media.server.spi.dsp.Codec;

/**
 *
 * @author kulikov
 */
public class MeanderDetector extends AbstractSink {

    private final static Format[] FORMATS = new Format[]{Codec.LINEAR_AUDIO};
    
    private int sampleRate;
    private double T;
    private short A;
    
    private short[] localBuffer;
    private int size;
    private int offset;
    private int count;
    
    private long seq;
    
    public MeanderDetector(String name) {
        super(name);
        sampleRate = (int)Codec.LINEAR_AUDIO.getSampleRate();
    }
    
    public void setPeriod(double T) {
        this.T = T/2;
        //preparing local buffer
        //we have to hold at least 3-4 periods of data for analysis
        size = (int)(sampleRate * this.T);
        localBuffer = new short[4*size];
    }
    
    public void setAmplitude(short A) {
        this.A = A;
    }
    
    public Format[] getFormats() {
        return FORMATS;
    }

    public boolean isAcceptable(Format format) {
        return format.matches(Codec.LINEAR_AUDIO);
    }

    @Override
    public void start() {
        seq = 0;
        super.start();
    }
    
    private boolean checkShock(short a, short b) {
        if (a == 0) {
            return b == A;
        } else if (a == A) {
            return b == 0;
        }
        return false;
    }
    
    private void analysis() {
        int p1 = 0;
        for (int i = 0; i < localBuffer.length - 1; i++) {
            if (localBuffer[i] != localBuffer[i+1]) {
                int delta = i - p1;
                p1 = i;                
                if (Math.abs(delta - size ) < 2) {
                    count++;
                    if (count == 3 && checkShock(localBuffer[i], localBuffer[i+1])) {
                        count = 0;
                        sendEvent(new MeanderEvent(this, MeanderEvent.EVENT_MEANDER));
                        break;
                    }
                }
            }
        }
    }
    
    public void onMediaTransfer(Buffer buffer) throws IOException {
        //checking sequence number
        if (seq != 0 && (buffer.getSequenceNumber() - seq) != 1) {
            sendEvent(new MeanderEvent(this, MeanderEvent.EVENT_OUT_OF_SEQUENCE));
        }        
        seq = buffer.getSequenceNumber();
        
        if (!buffer.getFormat().matches(Codec.LINEAR_AUDIO)) {
            sendEvent(new MeanderEvent(this, MeanderEvent.EVENT_FORMAT_MISSMATCH));
        }
        
        //checking data
        byte[] data = (byte[]) buffer.getData();
        for (int i = 0; i < buffer.getLength() - 1; i += 2) {
            if (offset < localBuffer.length) {
                localBuffer[offset++] = (short)((data[i] & 0xff) | (data[i+1] << 8));
            } else {
                analysis();
                offset = 0;
            }
        }
    }

}