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我的项目是创建一个可以对音频文件进行特征提取和分类的 Android 应用程序。所以首先，我正在创建一个 Java 应用程序作为测试运行。

我正在尝试使用 jAudio 的特征提取器包从音频文件中提取音频特征。

作为初学者，我想输入一个 .wav 文件并对该文件运行特征提取操作，然后将结果存储为 .ARFF 文件。

但是，我从项目中的包中收到以下 NullPointer 异常错误：

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)

最初我认为这是一个文件权限问题（即，由于缺少权限，不允许程序写入文件），但即使在授予 Eclipse 4.2.2 各种权限之后（我正在运行 Windows 7， 64 位版本），我仍然收到 NullException 错误。

下面给出了异常异常的包代码：

/**
     * 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);
        }
    }

这是主要的应用程序代码：

 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.

       }
     }

您可以在此处下载整个项目（目前已完成）。

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1 回答 1

0

这可能有点晚了，但我遇到了同样的问题，我将其追踪到从未在 DataModel 中设置的 featureKey 和 featureValue。这些没有固定的方法，但它们是公共领域。这是我的代码：

    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();
        }
    }

}

我使用 GUI 创建了 settings.xml 文件，只是从保存 jar 的目录中复制了 features.xml 文件。

希望这可以帮助

于 2016-03-16T10:04:05.760 回答