iPhone低通滤波器

iPhone低通滤波器：优化音频体验的必备工具

swift
import AVFoundation
func applyLowPassFilter(to audioURL: URL) {
    let audioAsset = AVURLAsset(url: audioURL)
    let audioTrack = audioAsset.tracks(withMediaType: .audio).first
    
    guard let track = audioTrack else {
        print("No audio track found!")
        return
    }
    
    let composition = AVMutableComposition()
    let compositionTrack = composition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid)
    
    do {
        try compositionTrack?.insertTimeRange(CMTimeRange(start: .zero, duration: audioAsset.duration), of: track, at: .zero)
        
        let lowPassFilter = AVAudioUnitLowPassFilter()
        lowPassFilter.cutoffFrequency = 5000 // 设置截止频率为5000Hz
        
        let audioEngine = AVAudioEngine()
        let audioPlayerNode = AVAudioPlayerNode()
        
        audioEngine.attach(audioPlayerNode)
        audioEngine.attach(lowPassFilter)
        
        audioEngine.connect(audioPlayerNode, to: lowPassFilter, format: compositionTrack!.format)
        audioEngine.connect(lowPassFilter, to: audioEngine.outputNode, format: compositionTrack!.format)
        
        audioPlayerNode.scheduleFile(audioURL, at: nil)
        
        try audioEngine.start()
        audioPlayerNode.play()
    } catch {
        print("Failed to apply low pass filter: \(error)")
    }
}