jAudio Feature Extractor : Null Exception

Question

My project is to create an Android app that can perform feature extraction and classification of audio files. So first, I'm creating a Java application as a test run.

I'm attempting to use jAudio's feature extractor package to extract audio features from an audio file.

As a starter, I want to input a .wav file and run the feature extraction operation upon that file, and then store the results as an .ARFF file.

However, I'm getting the below NullPointer Exception error from a package within the project:

Exception in thread "main" java.lang.NullPointerException
    at java.io.DataOutputStream.writeBytes(Unknown Source)
    at jAudioFeatureExtractor.jAudioTools.FeatureProcessor.writeValuesARFFHeader(FeatureProcessor.java:853)
    at jAudioFeatureExtractor.jAudioTools.FeatureProcessor.<init>(FeatureProcessor.java:258)
    at jAudioFeatureExtractor.DataModel.extract(DataModel.java:308)
    at Mfccarffwriter.main(Mfccarffwriter.java:70)

Initially I thought it was a file permission issue(i.e, the program was not being allowed to write a file because of lack of permissions), but even after granting every kind of permission to Eclipse 4.2.2(I'm running Windows 7, 64 bit version), I'm still getting the NullException bug.

The package code where the offending exception originates from is given below:

/**
     * Write headers for an ARFF file. If saving for overall features, this must
     * be postponed until the overall features have been calculated. If this a
     * perWindow arff file, then all the feature headers can be extracted now
     * and no hacks are needed.
     * <p>
     * <b>NOTE</b>: This procedure breaks if a feature to be saved has a
     * variable number of dimensions
     * 
     * @throws Exception
     */
    private void writeValuesARFFHeader() throws Exception {
        String sep = System.getProperty("line.separator");
        String feature_value_header = "@relation jAudio" + sep;
        values_writer.writeBytes(feature_value_header);   // exception here
        if (save_features_for_each_window && !save_overall_recording_features) {
            for (int i = 0; i < feature_extractors.length; ++i) {
                if (features_to_save[i]) {
                    String name = feature_extractors[i].getFeatureDefinition().name;
                    int dimension = feature_extractors[i]
                            .getFeatureDefinition().dimensions;
                    for (int j = 0; j < dimension; ++j) {
                        values_writer.writeBytes("@ATTRIBUTE \"" + name + j
                                + "\" NUMERIC" + sep);
                    }
                }
            }
            values_writer.writeBytes(sep);
            values_writer.writeBytes("@DATA" + sep);
        }
    }

Here's the main application code:

 import java.io.*;
import java.util.Arrays;

import com.sun.xml.internal.bind.v2.runtime.RuntimeUtil.ToStringAdapter;

import jAudioFeatureExtractor.Cancel;
import jAudioFeatureExtractor.DataModel;
import jAudioFeatureExtractor.Updater;
import jAudioFeatureExtractor.Aggregators.AggregatorContainer;
import jAudioFeatureExtractor.AudioFeatures.FeatureExtractor;
import jAudioFeatureExtractor.AudioFeatures.MFCC;
import jAudioFeatureExtractor.DataTypes.RecordingInfo;
import jAudioFeatureExtractor.jAudioTools.*;


     public static void main(String[] args) throws Exception {

         // Display information about the wav file
         File extractedFiletoTest = new File("./microwave1.wav");

         String randomID = Integer.toString((int) Math.random());

         String file_path = "E:/Weka-3-6/tmp/microwave1.wav";
         AudioSamples sampledExampleFile = new AudioSamples(extractedFiletoTest,randomID,false);

         RecordingInfo[] samplefileInfo = new RecordingInfo[5];
         samplefileInfo[1] = new RecordingInfo(randomID, file_path, sampledExampleFile, true);

         double samplingrate= sampledExampleFile.getSamplingRateAsDouble();
         int windowsize= 4096;
         boolean normalize = false;

        OutputStream valsavepath = new FileOutputStream(".\\values");
         OutputStream defsavepath = new FileOutputStream(".\\definitions");

         boolean[] featurestosaveamongall = new boolean[10];
         Arrays.fill(featurestosaveamongall, Boolean.TRUE);

         double windowoverlap = 0.0;

        DataModel mfccDM = new DataModel("features.xml",null);

         mfccDM.extract(windowsize, 0.5, samplingrate, true, true, false, samplefileInfo, 1); /// invokes the writeValuesARFFHeader function.

       }
     }

You can download the whole project (done so far)here.

Answer 1

This may be a bit late but I had the same issue and I tracked it down to the featureKey and featureValue never being set in the DataModel. There is not a set method for these but they are public field. Here is my code:

    package Sound;

import jAudioFeatureExtractor.ACE.DataTypes.Batch;
import jAudioFeatureExtractor.DataModel;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;

public class Analysis {

    private static String musicFile = "/home/chris/IdeaProjects/AnotherProj/res/SheMovesInHerOwnWay15s.wav";
    private static String featureFile = "/home/chris/IdeaProjects/AnotherProj/res/features.xml";
    private static String settingsFile = "/home/chris/IdeaProjects/AnotherProj/res/settings.xml";
    private static String FKOuputFile = "/home/chris/IdeaProjects/AnotherProj/res/fk.xml";
    private static String FVOuputFile = "/home/chris/IdeaProjects/AnotherProj/res/fv.xml";

    public static void main(String[] args){
        Batch batch = new Batch(featureFile, null);
        try{
            batch.setRecordings(new File[]{new File(musicFile)});
            batch.getAggregator();
            batch.setSettings(settingsFile);

            DataModel dm = batch.getDataModel();
            OutputStream valsavepath = new FileOutputStream(FVOuputFile);
            OutputStream defsavepath = new FileOutputStream(FKOuputFile);
            dm.featureKey = defsavepath;
            dm.featureValue = valsavepath;
            batch.setDataModel(dm);

            batch.execute();
        }
        catch (Exception e){
            e.printStackTrace();
        }
    }

}

I created the settings.xml file using the GUI and just copied the features.xml file from the directory where you saved the jar.

Hope this helps