Sound Demo 3

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<language>Java</language>
<code id="4b58377106264" hidden>
javax.sound.sampled.AudioFormat audioFormat;
javax.sound.sampled.AudioInputStream audioInputStream;
javax.sound.sampled.SourceDataLine sourceDataLine;
float sampleRate = 16000.0F;
int sampleSizeInBits = 16;
int channels = 1;
boolean signed = true;
boolean bigEndian = true;
audioData = new byte[16000*16];

void fillBuffer(double startat) {
 java.nio.ByteBuffer byteBuffer;
 java.nio.ShortBuffer shortBuffer;
 int byteLength;
 byteBuffer = java.nio.ByteBuffer.wrap(audioData);
 shortBuffer = byteBuffer.asShortBuffer();
 byteLength = audioData.length;

 channels = 1;//Java allows 1 or 2
 int bytesPerSamp = 2;
 int sampLength = byteLength / bytesPerSamp;
 for (int cnt = 0; cnt < sampLength; cnt++)
 {
  double time = cnt / sampleRate;
  double sinValue = playFunction(startat/2+time);
  shortBuffer.put((short)(16000 * sinValue));
 }
}

void draw(int dauer, double start){ 
 canvas.clear(); 
 double oldy = 100;
 canvas.setColor(200,200,200);
 canvas.line(0,100,600,100);
 canvas.setColor(0,0,0);
 for(int x=0; x< 600; x++) {   
   double newy = 100+100*playFunction(start/2+((double)dauer/2/600*x));   
   if(start/2+(double)dauer/2/600*x == 0){
    canvas.setColor(200,200,200);
    canvas.line(x,0,x,200);
    canvas.setColor(0,0,0);
   }
   canvas.line((x-1),(int)(oldy),x,(int)(newy));  
   oldy = newy; 
 }
}

void play(int dauer, double startat){
 audioData = new byte[16000*dauer];
 try{
 fillBuffer(startat);
 InputStream byteArrayInputStream =  new ByteArrayInputStream(audioData);
 audioFormat = new javax.sound.sampled.AudioFormat(sampleRate, sampleSizeInBits, channels, signed, bigEndian);
 audioInputStream = new javax.sound.sampled.AudioInputStream(byteArrayInputStream, audioFormat,  
                        audioData.length / audioFormat.getFrameSize());
 javax.sound.sampled.DataLine.Info dataLineInfo = 
       new javax.sound.sampled.DataLine.Info(javax.sound.sampled.SourceDataLine.class, audioFormat);
 sourceDataLine = (javax.sound.sampled.SourceDataLine)javax.sound.sampled.AudioSystem.getLine(dataLineInfo);
 sourceDataLine.open(audioFormat);
 sourceDataLine.start();
 playBuffer = new byte[16384];
 int cnt;
 while ((cnt = audioInputStream.read(playBuffer, 0,playBuffer.length))!= -1)
  if (cnt > 0) sourceDataLine.write(playBuffer, 0, cnt);
 sourceDataLine.drain();
 sourceDataLine.stop();
 sourceDataLine.close();
 }
 catch (Exception e){e.printStackTrace();System.exit(0);}
}
</code>
Mit diesem Beispiel kann man mathematische Funktionen hörbar machen. Bei der Tonerzeugung wird nicht zwischen negativen und positiven Ausschlägen unterschieden. Ist y = 0 entsteht kein Ton. Schlägt y im negativen oder positiven Bereich aus, entsteht ein hoher Ton. Verändern Sie die Funktion zum Beispiel mit <tt>Math.sin(x)</tt>.

<eval id="4b58377106a33">
double playFunction(double x){
     double freq = 950.0;//arbitrary frequency
     return 
        (Math.sin(2*Math.PI*freq*x) +
         Math.sin(2*Math.PI*(freq/1.3)*x) +
         Math.sin(2*Math.PI*(freq/1.5)*x))/3.0;
}

draw(10,-5); // 10 Sekunden diese Funktion spielen und mit x=-5 beginnen
play(10,-5); 
</eval>

<canvas></canvas>