content: /**
   * Copyright 2004-2006 DFKI GmbH.
   * All Rights Reserved.  Use is subject to license terms.
   * <p/>
   * This file is part of MARY TTS.
   * <p/>
   * MARY TTS is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation, version 3 of the License.
   * <p/>
   * 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.
   * <p/>
   * You should have received a copy of the GNU Lesser General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  package marytts.signalproc.process;
  
  import java.io.File;
  
  import lib.sound.sampled.AudioFileFormat;
  import lib.sound.sampled.AudioInputStream;
  import lib.sound.sampled.AudioSystem;
  import marytts.signalproc.analysis.LpcAnalyser;
  import marytts.signalproc.analysis.LpcAnalyser.LpCoeffs;
  import marytts.signalproc.filter.FIRFilter;
  import marytts.signalproc.filter.RecursiveFilter;
  import marytts.signalproc.window.Window;
  import marytts.util.data.BufferedDoubleDataSource;
  import marytts.util.data.audio.AudioDoubleDataSource;
  import marytts.util.data.audio.DDSAudioInputStream;
  import marytts.util.math.ArrayUtils;
  
  
  /**
   * A base class for LPC-based analysis and resynthesis, which does nothing.
   *
   * @author Marc Schr&ouml;der
   */
  public class LPCAnalysisResynthesis implements InlineDataProcessor {
      protected int p;
  
      /**
       * Apply LPC analysis-resynthesis.
       *
       * @param p prediction order, i.e. number of LPC coefficients to compute.
       */
      public LPCAnalysisResynthesis(int p) {
          this.p = p;
      }
  
      public static void main(String[] args) throws Exception {
          for (int i = 0; i < args.length; i++) {
              AudioInputStream inputAudio = AudioSystem.getAudioInputStream(new File(args[i]));
              int samplingRate = (int) inputAudio.getFormat().getSampleRate();
              AudioDoubleDataSource signal = new AudioDoubleDataSource(inputAudio);
              int frameLength = Integer.getInteger("signalproc.lpcanalysissynthesis.framelength", 512).intValue();
              int predictionOrder = Integer.getInteger("signalproc.lpcanalysissynthesis.predictionorder", 20).intValue();
              FrameOverlapAddSource foas = new FrameOverlapAddSource(signal, Window.HANNING, true, frameLength, samplingRate, new LPCAnalysisResynthesis(predictionOrder));
              DDSAudioInputStream outputAudio = new DDSAudioInputStream(new BufferedDoubleDataSource(foas), inputAudio.getFormat());
              String outFileName = args[i].substring(0, args[i].length() - 4) + "_lpc_ar.wav";
              AudioSystem.write(outputAudio, AudioFileFormat.Type.WAVE, new File(outFileName));
          }
  
      }
  
      @Override
      public void applyInline(double[] data, int off, int len) {
          assert off == 0;
          assert len == data.length;
          // Compute LPC coefficients and residual
          LpCoeffs coeffs = LpcAnalyser.calcLPC(data, p);
          //double gain = coeffs.getGain();
          double[] residual = ArrayUtils.subarray(new FIRFilter(coeffs.getOneMinusA()).apply(data), 0, len);
          // Do something fancy with the lpc coefficients and/or the residual
          processLPC(coeffs, residual);
          // Resynthesise audio from residual and LPC coefficients
          double[] newData = new RecursiveFilter(coeffs.getA()).apply(residual);
          //System.err.println("Sum squared error:"+MathUtils.sumSquaredError(data, newData));
          System.arraycopy(newData, 0, data, 0, len);
      }
  
      /**
       * Process the LPC coefficients and/or the residual in place.
       * This method does nothing; subclasses may want to override it
       * to do something meaningful.
       *
       * @param coeffs   the LPC coefficients
       * @param residual the residual, of length framelength
       */
      protected void processLPC(LpCoeffs coeffs, double[] residual) {
      }
  
  }
  
  