samer@0: /*
samer@0:  *	Copyright (c) 2000, Samer Abdallah, King's College London.
samer@0:  *	All rights reserved.
samer@0:  *
samer@0:  *	This software is provided AS iS and WITHOUT ANY WARRANTY;
samer@0:  *	without even the implied warranty of MERCHANTABILITY or
samer@0:  *	FITNESS FOR A PARTICULAR PURPOSE.
samer@0:  */
samer@0: 
samer@0: package samer.units;
samer@0: 
samer@0: import samer.maths.*;
samer@0: import samer.core.*;
samer@0: import samer.core.types.*;
samer@0: import samer.tools.*;
samer@0: import samer.functions.*;
samer@0: import javax.sound.sampled.*;
samer@0: 
samer@0: /**
samer@0:  * Overlap and add input vectors into a buffer. At each iteration,
samer@0:  * the buffer is shifted by <hop> and the new data is added in.
samer@0:  */
samer@0: 
samer@0: public class OverlapAndAdd extends NamedTask
samer@0: {
samer@0: 	VVector			vec;	// input
samer@0: 	VVector			out;
samer@0: 	int				N, hop; // frame size, hop size
samer@0: 	double[]			x, y; // input and output arrays
samer@0: 	double[]			H; 	// array containing window, eg Hanning
samer@0: 
samer@0: 	/** Create overlap and add buffer for input vector with given hop size */
samer@0: 	
samer@0: 	public OverlapAndAdd(VVector input, int hop) throws Exception
samer@0: 	{
samer@0: 		super("overlap");
samer@0: 		vec = input; N = vec.size();
samer@0: 		out = new VVector("output",N);
samer@0: 		H=new double[N];
samer@0: 		x=vec.array();
samer@0: 		y=out.array();
samer@0: 		this.hop=hop;
samer@0: 	}
samer@0: 
samer@0: 	/** Sets windowing array to samples from the given function.
samer@0: 	 *  The domain [0,1) is mapped on to the array indices 0:N-1 
samer@0: 	 */ 
samer@0: 	
samer@0: 	public void setWindow(Function fn) {
samer@0: 		for (int i=0; i<N; i++) H[i] = (double)i/N;
samer@0: 		fn.apply(H);
samer@0: 	}
samer@0: 
samer@0: 	public VVector input() { return vec; }
samer@0: 	public VVector output() { return out; }
samer@0: 	public void setHop(int hop) { this.hop=hop; }
samer@0: 
samer@0: 	public void dispose() { out.dispose(); }
samer@0: 	public void run() throws Exception
samer@0: 	{
samer@0: 		// shift everything in buffer along
samer@0: 		System.arraycopy(y,hop,y,0,N-hop);
samer@0: 
samer@0: 		// addin new stuff
samer@0: 		int i=0;
samer@0: 		for (; i<N-hop; i++) y[i]+=H[i]*x[i];
samer@0: 		for (; i<N; i++) y[i]=H[i]*x[i];
samer@0: 
samer@0: 		out.changed();
samer@0: 	}
samer@0: }
samer@0: