feat: AudioLevel helper and AudioRecorder.onLevel

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
2026-10-01 15:00:40 +02:00
parent 2c4b096850
commit c8e16145e1
4 changed files with 78 additions and 3 deletions
@@ -0,0 +1,24 @@
+import Foundation
+
+public enum AudioLevel {
+    /// Reported for empty or silent buffers (log of zero would be -infinity).
+    public static let silenceFloorDbfs: Float = -120
+
+    public static func rmsDbfs(_ samples: [Float]) -> Float {
+        samples.withUnsafeBufferPointer { rmsDbfs($0) }
+    }
+
+    public static func rmsDbfs(_ samples: UnsafeBufferPointer<Float>) -> Float {
+        guard !samples.isEmpty else { return silenceFloorDbfs }
+        var sum: Float = 0
+        for sample in samples { sum += sample * sample }
+        let rms = (sum / Float(samples.count)).squareRoot()
+        guard rms > 0 else { return silenceFloorDbfs }
+        return max(silenceFloorDbfs, 20 * log10(rms))
+    }
+
+    /// VU reading for a dBFS level, where `referenceDbfs` is 0 VU.
+    public static func vu(fromDbfs dbfs: Float, referenceDbfs: Float = -20) -> Float {
+        dbfs - referenceDbfs
+    }
+}