我的项目播放音乐并不断将低音的“强度”写入文本文件。然而，大约一半的强度是错误的，这意味着我的傅里叶变换输出被猛拉或者其他东西。它会产生如下输出：http://pastebin.com/yxyBwv2Q所有条形应排成一行。该pastebin中有3种不同的音调，按照（3,1,2）的顺序，关于它们的击打力度。这是有道理的，该项目肯定会显示何时以及只有当低音击中时。它根本不光滑，有误差。
这是代码：
package script;
import javazoom.jl.decoder.BitstreamException;
import javazoom.jl.decoder.Decoder;
import javazoom.jl.decoder.DecoderException;
import javazoom.jl.decoder.Header;
import javazoom.jl.decoder.JavaLayerException;
import javazoom.jl.decoder.Obuffer;
import javazoom.jl.decoder.SampleBuffer;
import javazoom.jl.decoder.Bitstream;
import javazoom.jl.player.Player;
import java.text.NumberFormat;
import java.util.Arrays;
import java.awt.AWTException;
import java.awt.Robot;
import java.awt.event.KeyEvent;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.util.Map;
import javax.sound.sampled.AudioFileFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.UnsupportedAudioFileException;
import org.tritonus.share.sampled.file.TAudioFileFormat;
import edu.emory.mathcs.jtransforms.fft.DoubleFFT_1D;
public class MusicPlayer {
static double getDurationWithMp3Spi(File file)
throws UnsupportedAudioFileException, IOException {
AudioFileFormat fileFormat = AudioSystem.getAudioFileFormat(file);
if (fileFormat instanceof TAudioFileFormat) {
Map<?, ?> properties = ((TAudioFileFormat) fileFormat).properties();
String key = "duration";
Long microseconds = (Long) properties.get(key);
int mili = (int) (microseconds / 1000);
int sec = (mili / 1000);
int min = (mili / 1000) / 60;
return microseconds / 1000000.0;
} else {
throw new UnsupportedAudioFileException();}
}
public static void main(String[] args) throws IOException,
JavaLayerException, InterruptedException, UnsupportedAudioFileException, AWTException {
// TODO Auto-generated method stub
//E:\\Program Files (x86)\\Steam\\SteamApps\\common\\team fortress 2\\tf\\cfg\\script.cfg
FileInputStream mp3 = new FileInputStream("30hz.mp3");
FileInputStream mp3player = new FileInputStream("30hz.mp3");
File song = new File("30hz.mp3");
Decoder decoder = new Decoder();
Bitstream bitstream = new Bitstream(mp3);
Bitstream playerBitstream = new Bitstream(mp3player);
SampleBuffer currentBuffer = (SampleBuffer) decoder.decodeFrame(
bitstream.readFrame(), bitstream);
Player player = new Player(mp3player);
int bufferLength = currentBuffer.getBufferLength();
DoubleFFT_1D transform = new DoubleFFT_1D(bufferLength);
double duration = getDurationWithMp3Spi(song);
bitstream.unreadFrame();
bitstream.closeFrame();
String fov;
int x =0;
int placeholder=0;
double currentMaximum=Double.MIN_VALUE;
double maximum=20000;
int freq=0;
Robot robot = new Robot();
String text=" ";
String[] textAmp = new String[200];
for(int i=0;i<200;i++){
textAmp[i]="O";
for(int j=0;j<i;j++){
textAmp[i]=textAmp[i]+"O";
}
}
player.play(1);
player.play(1);
player.play(1);
player.play(1);
player.play(1);
player.play(1);
player.play(1);
player.play(1);
player.play(1);
player.play(1);
double intensity=0;
while (((x <= (int) (((44100 * (duration - 1)) / 1152.0))))) {
player.play(1);
currentBuffer = (SampleBuffer) decoder.decodeFrame(bitstream.readFrame(), bitstream);
short[] originalBufferArray = new short[bufferLength];
originalBufferArray = currentBuffer.getBuffer();
double[] doubleBufferArray = new double[bufferLength*2];
for(int i =0; i<bufferLength;i++){
doubleBufferArray[i]=(double)originalBufferArray[i];
}
double temp=0;
//BEGIN ARRAYLIST
// double[] organizedArray = new double[2304];
// for(int i=0;i<1152;i++){
// organizedArray[i*2]=doubleBufferArray[i];
// }
// for(int i=1152;i<2304;i++){
// organizedArray[((i-1152)*2)+1]=doubleBufferArray[i];
// }
//END ARRAYLIST
transform.complexForward(doubleBufferArray,0);
double[] finalArray = new double[bufferLength];
for(int i =0;i<10;i+=2){
finalArray[i/2]= Math.sqrt(Math.pow(doubleBufferArray[i],2)+(Math.pow(doubleBufferArray[i+1], 2)));
finalArray[i/2]= finalArray[i/2]/(double)(bufferLength/2.0);
if(finalArray[i/2]>currentMaximum){
currentMaximum=finalArray[i/2];
freq=i/2;
}
}
// if (freq==4){
// currentMaximum/=4;
// intensity=currentMaximum/maximum;
//
// }
// else if (freq==3){
// currentMaximum/=3;
// intensity=currentMaximum/maximum;
// }
// else if (freq==2){
// currentMaximum/=2;
// intensity=currentMaximum/maximum;
// }
// else{
intensity=currentMaximum/maximum;
int fovInt=(int)(90-(intensity*25));
// }
// text=String.valueOf(intensity);
// text=text.substring(2,4);
// placeholder = (int)Double.parseDouble(text);
try{
File script = new File("E:\\Program Files (x86)\\Steam\\SteamApps\\common\\team fortress 2\\tf\\cfg\\script.cfg");
BufferedWriter writer = new BufferedWriter(new FileWriter(script));
fov = "fov_desired " + fovInt +"\necho \"working\"";
writer.write(fov, 0 ,fov.length());
writer.flush();
writer.close();
robot.keyPress(KeyEvent.VK_NUM_LOCK );
robot.keyRelease(KeyEvent.VK_NUM_LOCK );
} finally{}
currentMaximum=Double.MIN_VALUE;
bitstream.unreadFrame();
bitstream.closeFrame();
x++;
}
/*
* 0~0hz
* 1~19.140625hz
* 2~38.28125hz
* 3~57.422145hz
* 4~76.56277
* 5~ 95.703395
*/
}
}
任何人都知道为什么我的傅立叶分析给我带来了奇怪的结果？一开始播放的歌曲也是如此，歌曲会与输出同步。
答案 0 :(得分：0)
对于与波形不同步的短FFT，根据输入信号相对于窗口边缘的相位，会有一些幅度的扇形。如果使用非矩形窗口（Von Hann等），使FFT更长，可能是您的低频长度的多个周期将最小化这一点。对于40 Hz，您可以尝试使用至少8192个样本（大约8个43 Hz周期）或更长的FFT。