引入 maven 依赖：
XML
<dependency>
<groupId>net.sourceforge.jtransforms</groupId>
<artifactId>jtransforms</artifactId>
<version>2.4.0</version>
</dependency>FourierTransformTest.java：
java
import edu.emory.mathcs.jtransforms.fft.DoubleFFT_1D;
import javax.sound.sampled.UnsupportedAudioFileException;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;
public class FourierTransformTest {
public static void main(String[] args) throws UnsupportedAudioFileException, IOException {
fastTest();
// slowTest();
}
public static void fastTest() throws UnsupportedAudioFileException, IOException {
double[] audio_src = AudioUtils.wavToDoubleArray( new File("C:\\E\\素材\\音频\\wav\\audio.wav") );
// 将 audio_src 进行 时域转频域
new DoubleFFT_1D(audio_src.length).realForward(audio_src);
// 截取转换成频域以后得 audio_src 的前半部分 作为 audio_target
// 这里拷贝频域模式下的 audio_src 的前半部分，因为是频域模式，所以前半部分和后半部分其实都包含 "完整" 的时域信息( 只是失真严重 )，如果是时域模式下直接砍一半，肯定会丢失一半的时域信息( 但是未丢失的时域信息的音质没有任何丢失 )
// 所以频域下的double[]砍一半其实是音质砍一半( 即频率信息丢失一半 )
// 这里 除以2实现了2x加速效果
double[] audio_target = Arrays.copyOfRange(audio_src, 0, audio_src.length / 2);
// 将 audio_target 进行频域转时域
new DoubleFFT_1D( audio_target.length ).realInverse( audio_target, true );
System.out.println("转换完毕");
// 将audio_target 时域 double[] 转换成 wav 文件
AudioUtils.doubleArrayToWAV( audio_target,new File( "C:\\E\\素材\\音频\\wav\\audio_target.wav" ) );
System.out.println("生成完毕");
}
public static void slowTest() throws UnsupportedAudioFileException, IOException {
double[] audio_src = AudioUtils.wavToDoubleArray( new File("C:\\E\\素材\\音频\\wav\\audio.wav") );
// 将 audio_src 进行 时域转频域
new DoubleFFT_1D(audio_src.length).realForward(audio_src);
// 实现了 0.5X 变速效果
double[] audio_zero = buildZeroDoubleValueArray( audio_src.length );
// 将转换成频域以后的 audio_src 和一个等长度的 全是0的doublep[]合并( 可以把这个 audio_zero看做一个频域格式的 double[]，只是各个频率下的振幅全是0)
double[] audio_target = combineArray( audio_src,audio_zero );
// 将 audio_target 频域转时域
new DoubleFFT_1D( audio_target.length ).realInverse( audio_target, true );
System.out.println("转换完毕");
// 将时域格式下的 audio_target 转成 wav 文件
AudioUtils.doubleArrayToWAV( audio_target,new File( "C:\\E\\素材\\音频\\wav\\audio_target.wav" ) );
System.out.println("生成完毕");
}
private static double[] buildZeroDoubleValueArray(int length) {
double[] doubleArray = new double[length];
for (int i = 0; i < length; i++) {
doubleArray[i]=0d;
}
return doubleArray;
}
private static double[] combineArray(double[]... arrays) {
int arrayCount = arrays.length;
int totalLength = 0;
for( int i=0;i<arrayCount;i++ ){
totalLength += arrays[ i ].length;
}
double[] array_combine = new double[ totalLength ];
int index = 0;
for( int arrayNum=0;arrayNum<arrayCount;arrayNum++ ){
double[] array = arrays[arrayNum];
for (double v:array){
array_combine[index] = v;
index++;
}
}
return array_combine;
}
}用到的工具类 AudioUtils.java：
java
import javax.sound.sampled.*;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;
public class AudioUtils {
public static void main(String[] args) throws UnsupportedAudioFileException, IOException {
File file = new File("C:\\E\\素材\\音频\\wav\\一生所爱.wav");
double[] doubleArray = wavToDoubleArray(file);
System.out.println( doubleArray.length );
int partLength = doubleArray.length / 10;
doubleArrayToWAV( Arrays.copyOfRange(doubleArray, 0, partLength),new File( "C:\\E\\素材\\音频\\wav\\一生所爱_part1.wav" ) );
doubleArrayToWAV( Arrays.copyOfRange(doubleArray, partLength, partLength * 2),new File( "C:\\E\\素材\\音频\\wav\\一生所爱_part2.wav" ) );
doubleArrayToWAV( Arrays.copyOfRange(doubleArray, partLength * 2, partLength * 3),new File( "C:\\E\\素材\\音频\\wav\\一生所爱_part3.wav" ) );
doubleArrayToWAV( Arrays.copyOfRange(doubleArray, partLength * 3, partLength * 4),new File( "C:\\E\\素材\\音频\\wav\\一生所爱_part4.wav" ) );
doubleArrayToWAV( Arrays.copyOfRange(doubleArray, partLength * 4, partLength * 5),new File( "C:\\E\\素材\\音频\\wav\\一生所爱_part5.wav" ) );
doubleArrayToWAV( Arrays.copyOfRange(doubleArray, partLength * 5, partLength * 6),new File( "C:\\E\\素材\\音频\\wav\\一生所爱_part6.wav" ) );
}
public static double[] wavToDoubleArray(File mp3File) throws UnsupportedAudioFileException, IOException {
AudioInputStream audioInputStream = AudioSystem.getAudioInputStream(mp3File);
AudioFormat audioFormat = audioInputStream.getFormat();
int numChannels = audioFormat.getChannels();
int sampleSizeInBytes = audioFormat.getSampleSizeInBits() / 8;
int frameSize = numChannels * sampleSizeInBytes;
int bufferSize = (int) (audioInputStream.getFrameLength() * frameSize);
byte[] audioBytes = new byte[bufferSize];
audioInputStream.read(audioBytes);
double[] audioData = new double[audioBytes.length / 2];
for (int i = 0, j = 0; i < audioBytes.length; i += 2, j++) {
int sample = (audioBytes[i + 1] << 8) | (audioBytes[i] & 0xFF);
audioData[j] = sample / 32768.0;
}
return audioData;
}
public static void doubleArrayToWAV(double[] audioData, File outputFile) throws IOException, UnsupportedAudioFileException {
AudioFormat audioFormat = new AudioFormat(44100, 16, 2, true, false);
byte[] audioBytes = new byte[audioData.length * 2];
for (int i = 0, j = 0; i < audioData.length; i++, j += 2) {
short sample = (short) (audioData[i] * 32767);
audioBytes[j] = (byte) (sample & 0xFF);
audioBytes[j + 1] = (byte) ((sample >> 8) & 0xFF);
}
AudioInputStream audioInputStream = new AudioInputStream(new ByteArrayInputStream(audioBytes), audioFormat, audioData.length);
AudioSystem.write(audioInputStream, AudioFileFormat.Type.WAVE, outputFile);
}
}