TNS.java

package net.sourceforge.jaad.aac.tools;

import net.sourceforge.jaad.aac.AACException;
import net.sourceforge.jaad.aac.SampleFrequency;
import net.sourceforge.jaad.aac.syntax.SyntaxConstants;
import net.sourceforge.jaad.aac.syntax.IBitStream;
import net.sourceforge.jaad.aac.syntax.ICSInfo;
import net.sourceforge.jaad.aac.syntax.ICStream;

/**
 * This class is part of JAAD ( jaadec.sourceforge.net ) that is distributed
 * under the Public Domain license. Code changes provided by the JCodec project
 * are distributed under FreeBSD license.
 * 
 * Temporal Noise Shaping
 * @author in-somnia
 */
public class TNS implements SyntaxConstants, TNSTables {

	private static final int TNS_MAX_ORDER = 20;
	private static final int[] SHORT_BITS = {1, 4, 3}, LONG_BITS = {2, 6, 5};
	//bitstream
	private int[] nFilt;
	private int[][] length, order;
	private boolean[][] direction;
	private float[][][] coef;

	public TNS() {
		nFilt = new int[8];
		length = new int[8][4];
		direction = new boolean[8][4];
		order = new int[8][4];
		coef = new float[8][4][TNS_MAX_ORDER];
	}

	public void decode(IBitStream _in, ICSInfo info) throws AACException {
		final int windowCount = info.getWindowCount();
		final int[] bits = info.isEightShortFrame() ? SHORT_BITS : LONG_BITS;

		int w, i, filt, coefLen, coefRes, coefCompress, tmp;
		for(w = 0; w<windowCount; w++) {
			if((nFilt[w] = _in.readBits(bits[0]))!=0) {
				coefRes = _in.readBit();

				for(filt = 0; filt<nFilt[w]; filt++) {
					length[w][filt] = _in.readBits(bits[1]);

					if((order[w][filt] = _in.readBits(bits[2]))>20) throw new AACException("TNS filter out of range: "+order[w][filt]);
					else if(order[w][filt]!=0) {
						direction[w][filt] = _in.readBool();
						coefCompress = _in.readBit();
						coefLen = coefRes+3-coefCompress;
						tmp = 2*coefCompress+coefRes;

						for(i = 0; i<order[w][filt]; i++) {
							coef[w][filt][i] = TNS_TABLES[tmp][_in.readBits(coefLen)];
						}
					}
				}
			}
		}
	}

	public void process(ICStream ics, float[] spec, SampleFrequency sf, boolean decode) {
		//TODO...
	}
}