import Foundation
@MainActor
@Observable
final class AudioLevelMonitor {
private(set) var levels: [Float]
private(set) var peakLevel: Float = 0
private(set) var averageLevel: Float = 0
private(set) var isSilent: Bool = true
private(set) var consecutiveSilentFrames: Int = 0
private let bandCount: Int
private let silenceThreshold: Float = 0.001
private var recentPeaks: [Float] = []
private let peakHistorySize = 60
private var adaptiveGain: Float = 5.0
init(bandCount: Int = 7) {
self.bandCount = bandCount
self.levels = Array(repeating: 0, count: bandCount)
}
var hasAudioActivity: Bool {
!isSilent && peakLevel > silenceThreshold
}
var microphoneStatus: MicrophoneStatus {
if consecutiveSilentFrames > 50 {
return .blocked
} else if isSilent {
return .silent
} else {
return .active
}
}
func update(from samples: [Float]) {
guard !samples.isEmpty else {
markSilent()
return
}
let samplesPerBand = max(1, samples.count / bandCount)
var newLevels: [Float] = []
var maxLevel: Float = 0
var sum: Float = 0
for i in 0..<bandCount {
let start = i * samplesPerBand
let end = min(start + samplesPerBand, samples.count)
guard start < samples.count else {
newLevels.append(0)
continue
}
let band = Array(samples[start..<end])
let rms = sqrt(band.map { $0 * $0 }.reduce(0, +) / Float(band.count))
let normalizedLevel = min(1.0, rms * adaptiveGain)
newLevels.append(normalizedLevel)
maxLevel = max(maxLevel, rms)
sum += rms
}
levels = newLevels
peakLevel = maxLevel
averageLevel = sum / Float(bandCount)
if maxLevel < silenceThreshold {
consecutiveSilentFrames += 1
isSilent = true
} else {
consecutiveSilentFrames = 0
isSilent = false
updateAdaptiveGain(currentPeak: maxLevel)
}
}
private func updateAdaptiveGain(currentPeak: Float) {
recentPeaks.append(currentPeak)
if recentPeaks.count > peakHistorySize {
recentPeaks.removeFirst()
}
guard recentPeaks.count >= 10 else { return }
let sortedPeaks = recentPeaks.sorted()
let percentile90 = sortedPeaks[Int(Float(sortedPeaks.count) * 0.9)]
if percentile90 > 0.001 {
let targetGain = 0.7 / percentile90
let clampedGain = max(2.0, min(20.0, targetGain))
adaptiveGain = adaptiveGain * 0.95 + clampedGain * 0.05
}
}
func reset() {
levels = Array(repeating: 0, count: bandCount)
peakLevel = 0
averageLevel = 0
isSilent = true
consecutiveSilentFrames = 0
recentPeaks.removeAll()
adaptiveGain = 5.0
}
private func markSilent() {
consecutiveSilentFrames += 1
isSilent = true
peakLevel = 0
averageLevel = 0
}
}
enum MicrophoneStatus: String, CustomStringConvertible {
case active = "Active"
case silent = "Silent"
case blocked = "Blocked (no audio)"
var description: String { rawValue }
}
