Implement volume() on MusicMixer

- Implement volume changer on MusicMixer
almic · Mar 27, 2024 · faeaa89 · faeaa89
1 parent 7911d50
commit faeaa89
Showing 1 changed file with 71 additions and 2 deletions.
diff --git a/src/MusicMixer.ts b/src/MusicMixer.ts
@@ -1,5 +1,7 @@
-import AudioSourceNode, { AudioAdjustmentOptions } from './AudioSourceNode';
+import AudioSourceNode, { AudioAdjustmentOptions, AudioRampType } from './AudioSourceNode';
 import TrackSingle, { Track, TrackGroup } from './Track';
+import buildOptions from './defaults';
+import * as defaults from './defaults';
 
 /**
  * MusicMixer
@@ -89,9 +91,76 @@ class MusicMixer {
      * @returns {MusicMixer} this MusicMixer
      */
     public volume(volume: number, options?: AudioAdjustmentOptions): MusicMixer {
-        console.log(`stub volume changed to ${volume} with ${options}`);
+        const currentValue = this.gainNode.gain.value;
+        const difference = volume - currentValue;
+        const adjustment = options ? buildOptions(options) : defaults.automationDefault;
+
+        // Stop automations and immediately ramp.
+        if (Math.abs(difference) < Number.EPSILON) {
+            this.gainNode.gain.cancelAndHoldAtTime(this.currentTime);
+            this.gainNode.gain.setValueAtTime(currentValue, this.currentTime);
+            this.gainNode.gain.linearRampToValueAtTime(volume, adjustment.delay + this.currentTime);
+            return this;
+        }
+
+        this.gainNode.gain.cancelAndHoldAtTime(adjustment.delay + this.currentTime);
+        this.gainNode.gain.setValueAtTime(currentValue, adjustment.delay + this.currentTime);
+        if (Array.isArray(adjustment.ramp)) {
+            const valueCurve = [];
+            for (const markiplier of adjustment.ramp) {
+                valueCurve.push(currentValue + difference * markiplier);
+            }
+            this.gainNode.gain.setValueCurveAtTime(
+                valueCurve,
+                adjustment.delay + this.currentTime,
+                adjustment.duration,
+            );
+            return this;
+        }
+
+        switch (adjustment.ramp) {
+            case AudioRampType.EXPONENTIAL: {
+                this.gainNode.gain.exponentialRampToValueAtTime(
+                    volume,
+                    adjustment.delay + adjustment.duration + this.currentTime,
+                );
+                break;
+            }
+            case AudioRampType.LINEAR: {
+                this.gainNode.gain.linearRampToValueAtTime(
+                    volume,
+                    adjustment.delay + adjustment.duration + this.currentTime,
+                );
+                break;
+            }
+            case AudioRampType.NATURAL: {
+                // Logarithmic approach to value, it is 95% the way there after 3 timeConstant, so we linearly ramp at that point
+                const timeConstant = adjustment.duration / 4;
+                this.gainNode.gain.setTargetAtTime(volume, adjustment.delay + this.currentTime, timeConstant);
+                this.gainNode.gain.cancelAndHoldAtTime(
+                    adjustment.delay + timeConstant * 3 + this.currentTime,
+                );
+                // The following event is implicitly added, per WebAudio spec.
+                // https://webaudio.github.io/web-audio-api/#dom-audioparam-cancelandholdattime
+                // this.gainNode.gain.setValueAtTime(currentValue + (difference * (1 - Math.pow(Math.E, -3))), timeConstant * 3 + this.currentTime);
+                this.gainNode.gain.linearRampToValueAtTime(
+                    volume,
+                    adjustment.delay + adjustment.duration + this.currentTime,
+                );
+                break;
+            }
+            default: {
+                this.gainNode.gain.setValueAtTime(volume, adjustment.delay);
+                break;
+            }
+        }
+
         return this;
     }
+
+    get currentTime(): number {
+        return this.audioContext.currentTime;
+    }
 }
 
 export default MusicMixer;