data: normalize before/after noise

indutny · Oct 24, 2020 · f4cfca4 · f4cfca4
1 parent 3e42a4a
commit f4cfca4
Showing 1 changed file with 15 additions and 11 deletions.
diff --git a/src/data.mjs b/src/data.mjs
@@ -10,6 +10,17 @@ export default class Data {
     this.fftOut = this.fft.createComplexArray();
   }
 
+  normalize(list) {
+    let max = 0;
+    for (let i = 0; i < list.length; i++) {
+      max = Math.max(max, Math.abs(list[i]));
+    }
+
+    for (let i = 0; i < list.length; i++) {
+      list[i] /= max;
+    }
+  }
+
   sample(freq) {
     // E6=1318
     // A1=55
@@ -19,32 +30,25 @@ export default class Data {
     const f = freq / this.sampleRate;
     const phase = Math.random();
     const harmonicFade = 0.25 + 0.25 * Math.random();
-    const noise = Math.random() * 0.3;
-
-    let norm = 0;
-    for (let h = 0; h < 3; h++) {
-      norm += Math.pow(harmonicFade, h);
-    }
 
     this.fftIn.fill(0);
-    let max = 0;
     for (let t = 0; t < this.fftIn.length; t++) {
       let signal = 0;
 
       for (let h = 0; h < 3; h++) {
         signal += Math.sin(2 * Math.PI * (Math.pow(2, h) * f * t + phase)) *
           Math.pow(harmonicFade, h);
       }
-      signal /= norm;
 
-      signal = signal * (1 - noise) + Math.random() * noise;
-      max = Math.max(max, Math.abs(signal));
       this.fftIn[t] = signal;
     }
+    this.normalize(this.fftIn);
 
+    const noise = Math.random() * 0.3;
     for (let t = 0; t < this.fftIn.length; t++) {
-      this.fftIn[t] /= max;
+      this.fftIn[t] = this.fftIn[t] * (1 - noise) + Math.random() * noise;
     }
+    this.normalize(this.fftIn);
 
     this.fft.realTransform(this.fftOut, this.fftIn);