LPCConverter.java

/*
  LPCConverter.java

  (c) 2012-2014 Edward Swartz

  All rights reserved. This program and the accompanying materials
  are made available under the terms of the Eclipse Public License v1.0
  which accompanies this distribution, and is available at
  http://www.eclipse.org/legal/epl-v10.html
 */
package v9t9.engine.speech.encode;

import v9t9.common.speech.ILPCParameters;
import v9t9.engine.speech.LPCParameters;
import v9t9.engine.speech.RomTables;

/**
 * @author ejs
 *
 */
public class LPCConverter {

	public LPCConverter() {
		
	}
	public ILPCParameters apply(LPCAnalysisFrame results) {
		boolean voiced = results.invPitch != 0;
		
		LPCParameters params = new LPCParameters();
		if (voiced) {
			//int pVal = (int) Math.max(0x1000, Math.min(0xA000, ((float)results.invPitch*hertz/origHz*256)));
			int pVal = (int) Math.max(0x1000, Math.min(0xA000, results.pitch*256));
			params.pitchParam = lookup(RomTables.pitchtable, pVal);
			params.pitch = RomTables.pitchtable[params.pitchParam];
		} else {
			params.pitch = 0;
			params.pitchParam = 0;
		}
		
		int eVal = (int) (Math.min(0x7fc0, (int) (results.power * results.powerScale * 0x7fbf)));
		params.energyParam = lookup(RomTables.energytable, eVal);
		params.energy = RomTables.energytable[params.energyParam];
		
		int max = Math.min(results.coefs.length, voiced ? 10 : 4);
		for (int k = 0; k < max; k++) {
			int kVal = (int) (Math.max(-1.0f, Math.min(1.0f, results.coefs[k + results.coefsOffs])) * 32767);
			params.kParam[k] = lookup(RomTables.ktable[k], kVal);
			params.kVal[k] = RomTables.ktable[k][params.kParam[k]];
		}
		for (int k = max; k < 10; k++) {
			params.kParam[k] = 0;
			params.kVal[k] = 0;
		}
		
		return params;
	}

	private int lookup(short[] ks, int fk) {
		int diff = Integer.MAX_VALUE;
		int matchIdx = 0;
		int idx = 0;
		for (short k : ks) {
			int curdiff = Math.abs(k - fk);
			if (curdiff < diff) {
				matchIdx = idx;
				diff = curdiff;
			}
			idx++;
		}
		return matchIdx;
	}
	
	private int lookup(int[] ks, int fk) {
		int diff = Integer.MAX_VALUE;
		int matchIdx = 0;
		int idx = 0;
		for (int k : ks) {
			int curdiff = Math.abs(k - fk);
			if (curdiff < diff) {
				matchIdx = idx;
				diff = curdiff;
			}
			idx++;
		}
		return matchIdx;
	}
}