Smart Volume: Studio-Quality AGC & Intelligent Loudness Compensation

FineTune/Audio/EQ/BiquadMath.swift

@@ -89,6 +89,28 @@ enum BiquadMath {
         return [b0 / a0, b1 / a0, b2 / a0, a1 / a0, a2 / a0]
     }
 
+    /// Compute low-pass biquad coefficients (RBJ cookbook, 2nd-order Butterworth)
+    /// Returns [b0, b1, b2, a1, a2] normalized by a0 for vDSP_biquad
+    static func lowPassCoefficients(
+        frequency: Double,
+        q: Double,
+        sampleRate: Double
+    ) -> [Double] {
+        let omega = 2.0 * .pi * frequency / sampleRate
+        let sinW = sin(omega)
+        let cosW = cos(omega)
+        let alpha = sinW / (2.0 * q)
+
+        let b0 =  (1.0 - cosW) / 2.0
+        let b1 =  1.0 - cosW
+        let b2 =  (1.0 - cosW) / 2.0
+        let a0 =  1.0 + alpha
+        let a1 = -2.0 * cosW
+        let a2 =  1.0 - alpha
+
+        return [b0 / a0, b1 / a0, b2 / a0, a1 / a0, a2 / a0]
+    }
+
     /// Compute high-pass biquad coefficients (RBJ cookbook, 2nd-order Butterworth)
     /// Returns [b0, b1, b2, a1, a2] normalized by a0 for vDSP_biquad
     static func highPassCoefficients(

FineTune/Audio/Engine/AudioEngine.swift

@@ -329,7 +329,8 @@ final class AudioEngine {
                     }
                     tap.updateLoudnessCompensation(
                         volume: self.effectiveLoudnessVolume(for: tap),
-                        enabled: loudnessEnabled
+                        enabled: loudnessEnabled,
+                        intensity: self.settingsManager.appSettings.loudnessCompensationIntensity
                     )
                 }
             }
@@ -627,7 +628,11 @@ final class AudioEngine {
             applyTapOutputState(to: tap, for: tap.app.id, deviceUIDs: tap.currentDeviceUIDs)
             tap.updateEQSettings(.flat)
             tap.updateAutoEQProfile(nil)
-            tap.updateLoudnessCompensation(volume: effectiveLoudnessVolume(for: tap), enabled: false)
+            tap.updateLoudnessCompensation(
+                volume: effectiveLoudnessVolume(for: tap),
+                enabled: false,
+                intensity: settingsManager.appSettings.loudnessCompensationIntensity
+            )
         }
 
         // 6. Re-apply from clean settings (re-establishes routing to system default)
@@ -646,7 +651,8 @@ final class AudioEngine {
             if settingsManager.appSettings.loudnessCompensationEnabled {
                 tap.updateLoudnessCompensation(
                     volume: effectiveLoudnessVolume(for: tap),
-                    enabled: true
+                    enabled: true,
+                    intensity: settingsManager.appSettings.loudnessCompensationIntensity
                 )
             }
         }
@@ -795,8 +801,23 @@ final class AudioEngine {
     }
 
     func setLoudnessCompensationEnabled(_ enabled: Bool) {
+        let intensity = settingsManager.loudnessCompensationIntensity
         for tap in taps.values {
-            tap.updateLoudnessCompensation(volume: effectiveLoudnessVolume(for: tap), enabled: enabled)
+            tap.updateLoudnessCompensation(
+                volume: effectiveLoudnessVolume(for: tap),
+                enabled: enabled,
+                intensity: intensity
+            )
+        }
+    }
+
+    func setLoudnessCompensationIntensity(_ intensity: Float) {
+        for tap in taps.values {
+            tap.updateLoudnessCompensation(
+                volume: effectiveLoudnessVolume(for: tap),
+                enabled: settingsManager.appSettings.loudnessCompensationEnabled,
+                intensity: intensity
+            )
         }
     }
 
@@ -808,6 +829,12 @@ final class AudioEngine {
         }
     }
 
+    func setLoudnessEqualizationIntensity(_ intensity: Float) {
+        for tap in taps.values {
+            tap.setLoudnessEqualizationIntensity(intensity)
+        }
+    }
+
     /// Apply AutoEQ profile to all taps currently routed to the given device.
     private func applyAutoEQToTaps(for deviceUID: String) {
         for tap in taps.values {
@@ -832,6 +859,7 @@ final class AudioEngine {
             autoEQPreampEnabled: settingsManager.autoEQPreampEnabled,
             loudnessVolume: deviceVolume * volumeState.getVolume(for: app.id),
             loudnessCompensationEnabled: settingsManager.appSettings.loudnessCompensationEnabled,
+            loudnessCompensationIntensity: settingsManager.appSettings.loudnessCompensationIntensity,
             loudnessEqualizerSettings: loudnessEqSettings
         )
     }
@@ -948,6 +976,8 @@ final class AudioEngine {
                     self.logger.debug("Switched \(app.name) to device: \(targetUID)")
                 } catch {
                     self.logger.error("Failed to switch device for \(app.name): \(error.localizedDescription)")
+                    self.logger.info("Falling back to recreateTap for \(app.name)")
+                    await self.recreateTap(for: app.id)
                 }
             }
         } else {
@@ -1067,7 +1097,12 @@ final class AudioEngine {
             try tap.activate(initial: initial)
             taps[app.id] = tap
 
-            // Catalog AutoEQ may not have been cached yet — kick off async resolve.
+            tap.setLoudnessEqualizationIntensity(settingsManager.appSettings.loudnessEqualizationIntensity)
+            tap.updateLoudnessCompensation(
+                volume: effectiveLoudnessVolume(for: tap),
+                enabled: settingsManager.appSettings.loudnessCompensationEnabled,
+                intensity: settingsManager.appSettings.loudnessCompensationIntensity
+            )
             if initial.autoEQProfile == nil {
                 applyAutoEQToTap(tap)
             }
@@ -1183,6 +1218,8 @@ final class AudioEngine {
                         self.applyAutoEQToTap(existingTap)
                     } catch {
                         self.logger.error("Failed to re-route \(app.name) to \(deviceUID): \(error.localizedDescription)")
+                        self.logger.info("Falling back to recreateTap for \(app.name)")
+                        await self.recreateTap(for: app.id)
                     }
                 }
                 appliedPIDs.insert(app.id)
@@ -1228,8 +1265,12 @@ final class AudioEngine {
             try tap.activate(initial: initial)
             taps[app.id] = tap
 
-            // Catalog AutoEQ may not have been cached yet — kick off async resolve.
-            // Imported profiles always hit the synchronous path above.
+            tap.setLoudnessEqualizationIntensity(settingsManager.appSettings.loudnessEqualizationIntensity)
+            tap.updateLoudnessCompensation(
+                volume: effectiveLoudnessVolume(for: tap),
+                enabled: settingsManager.appSettings.loudnessCompensationEnabled,
+                intensity: settingsManager.appSettings.loudnessCompensationIntensity
+            )
             if initial.autoEQProfile == nil {
                 applyAutoEQToTap(tap)
             }
@@ -1328,6 +1369,8 @@ final class AudioEngine {
                     self.applyAutoEQToTap(tap)
                 } catch {
                     self.logger.error("Failed to switch \(app.name) to \(targetUID): \(error.localizedDescription)")
+                    self.logger.info("Falling back to recreateTap for \(app.name)")
+                    await self.recreateTap(for: app.id)
                 }
             }
         }
@@ -1408,6 +1451,8 @@ final class AudioEngine {
                         self.applyAutoEQToTap(tap)
                     } catch {
                         self.logger.error("Failed to switch \(tap.app.name) to fallback: \(error.localizedDescription)")
+                        self.logger.info("Falling back to recreateTap for \(tap.app.name)")
+                        await self.recreateTap(for: tap.app.id)
                     }
                 }
 
@@ -1421,6 +1466,8 @@ final class AudioEngine {
                         self.logger.debug("Removed \(deviceName) from \(tap.app.name) multi-device output")
                     } catch {
                         self.logger.error("Failed to update \(tap.app.name) devices: \(error.localizedDescription)")
+                        self.logger.info("Falling back to recreateTap for \(tap.app.name) (multi-mode)")
+                        await self.recreateTap(for: tap.app.id, overridingDeviceUIDs: remainingUIDs)
                     }
                 }
             }
@@ -1480,6 +1527,8 @@ final class AudioEngine {
                         self.applyAutoEQToTap(tap)
                     } catch {
                         self.logger.error("Failed to switch \(tap.app.name) back to \(deviceName): \(error.localizedDescription)")
+                        self.logger.info("Falling back to recreateTap for \(tap.app.name)")
+                        await self.recreateTap(for: tap.app.id)
                     }
                 }
             }
@@ -1543,6 +1592,10 @@ final class AudioEngine {
             // macOS already auto-switched to the lower-priority device — restore
             // what the user was on (not highest priority — they may have chosen a mid-priority device)
             restoreConfirmedDefault()
+        } else if currentDefault == deviceUID {
+            // The reconnected device is the current default (e.g. macOS auto-switched to a higher-priority device)
+            // Route follows-default apps to it in case we deferred it earlier.
+            routeFollowsDefaultApps(to: deviceUID)
         }
 
         // Cancel any existing PENDING_AUTOSWITCH before entering a new one.
@@ -1941,9 +1994,9 @@ final class AudioEngine {
     /// Tears down and recreates a tap for a given PID, preserving routing and settings.
     /// Async: awaits full CoreAudio resource teardown before creating the replacement tap
     /// to prevent orphaned IO procs from accumulating (issue #176).
-    private func recreateTap(for pid: pid_t) async {
+    private func recreateTap(for pid: pid_t, overridingDeviceUIDs: [String]? = nil) async {
         guard let oldTap = taps.removeValue(forKey: pid) else { return }
-        let deviceUIDs = oldTap.currentDeviceUIDs
+        let deviceUIDs = overridingDeviceUIDs ?? oldTap.currentDeviceUIDs
         await oldTap.invalidateAsync()
 
         // Set cooldown to prevent thrashing