我在 java 中有一个基本的波发生器，但是当波的幅度急剧变化时，我需要一些东西来消除我得到的点击。即当我开始/停止播放波浪时，尤其是当我有哔哔声时。
Phrogz 对 SO 的回答提供了一个非常好的和简单的功能，但我不确定我是否正确实施它。
当我第一次尝试使用它时，我无法让它工作，但后来我似乎记得它工作得很好......我已经摆弄了很多我的代码，现在它似乎没有工作再次很好。
所以这是我最接近SSCCE的地方：
如果你玩这个，你会注意到当过滤器打开时（filter = true），波浪更安静，咔哒声也略微减少，但这似乎主要是由于音量的减少。每次哔哔声仍然有明显的“撞击”，我不想要，我不记得以前在那里......
import javax.sound.sampled.*;
public class Oscillator{
private static int SAMPLE_RATE = 22050;
private static short MAX_AMPLITUDE = Short.MAX_VALUE;
private static AudioFormat af = null;
private static SourceDataLine line = null;
private int frequency = 440; //Hz
private int numLoops = 1000;
private int beep = 100;
// set to true to apply low-pass filter
private boolean filter = true;
// set the amount of "smoothing" here
private int smoothing = 100;
private double oldValue;
public Oscillator(){
prepareLine();
}
public static void main(String[] args) {
System.out.println("Playing oscillator");
Oscillator osc = new Oscillator();
osc.play();
}
private void prepareLine(){
af = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED, SAMPLE_RATE, 16, 2, 4, SAMPLE_RATE, false);
try {
DataLine.Info info = new DataLine.Info(SourceDataLine.class, af);
if (!AudioSystem.isLineSupported(info)) {
System.out.println("Line does not support: " + af);
System.exit(0);
}
line = (SourceDataLine) AudioSystem.getLine(info);
line.open(af);
}
catch (Exception e) {
System.out.println(e.getMessage());
System.exit(0);
}
}
private void play() {
System.out.println("play");
int maxSize = (int) Math.round( (SAMPLE_RATE * af.getFrameSize())/ frequency );
byte[] samples = new byte[maxSize];
line.start();
double volume = 1;
int count = 0;
for (int i = 0; i < numLoops; i ++){
if (count == beep) {
if(volume==1) volume = 0;
else volume = 1;
count = 0;
}
count ++;
playWave(frequency, volume, samples);
}
line.drain();
line.stop();
line.close();
System.exit(0);
}
private void playWave(int frequency, double volLevel, byte[] samples) {
double amplitude = volLevel * MAX_AMPLITUDE;
int numSamplesInWave = (int) Math.round( ((double) SAMPLE_RATE)/frequency );
int index = 0;
for (int i = 0; i < numSamplesInWave; i++) {
double theta = (double)i/numSamplesInWave;
double wave = getWave(theta);
int sample = (int) (wave * amplitude);
if (filter) sample = applyLowPassFilter(sample);
// left sample
samples[index + 0] = (byte) (sample & 0xFF);
samples[index + 1] = (byte) ((sample >> 8) & 0xFF);
// right sample
samples[index + 2] = (byte) (sample & 0xFF);
samples[index + 3] = (byte) ((sample >> 8) & 0xFF);
index += 4;
}
int offset = 0;
while (offset < index){
double increment =line.write(samples, offset, index-offset);
offset += increment;
}
}
private double getWave(double theta){
double value = 0;
theta = theta * 2 * Math.PI;
value = getSin(theta);
//value = getSqr(theta);
return value;
}
private double getSin(double theta){
return Math.sin(theta);
}
private int getSqr(double theta){
if (theta <= Math.PI) return 1;
else return 0;
}
// implementation of basic low-pass filter
private int applyLowPassFilter(int sample){
int newValue = sample;
double filteredValue = oldValue + (newValue - oldValue) / smoothing;
oldValue = filteredValue;
return (int) filteredValue;
}
}
相关方法在最后。如果有人对此进行测试，如果您有耳机，请注意音量！
所以要么：
- 它正在工作，我只是期待太多这样一个简单的实现
- 我做错了什么，愚蠢而明显......
如果它只是 1。我应该/如何摆脱突然幅度变化带来的刺耳节拍/敲击/咔哒声？
如果它是 2. 好，应该是一个太长问题的简短回答。