iOS 中 如何通过 bandpassfilter, 对音频文件的声音进行过滤,并保存
在 iOS 中,你可以使用 AVFoundation
框架来处理音频文件,并通过 AVAudioEngine
和 AVAudioUnitEQ
来实现带通滤波器(Bandpass Filter)。以下是一个示例代码,展示了如何对音频文件应用带通滤波器并保存处理后的音频文件。
首先,确保在你的项目中导入了 AVFoundation
框架。
然后,使用以下代码来实现音频处理和保存:
import AVFoundation
func applyBandpassFilter(inputURL: URL, outputURL: URL, centerFrequency: Float, bandwidth: Float, completion: @escaping (Bool, Error?) -> Void) {
let audioFile = try! AVAudioFile(forReading: inputURL)
let format = audioFile.processingFormat
let frameCount = UInt32(audioFile.length)
let audioEngine = AVAudioEngine()
let playerNode = AVAudioPlayerNode()
let eqNode = AVAudioUnitEQ(numberOfBands: 1)
let band = eqNode.bands.first!
band.filterType = .bandPass
band.frequency = centerFrequency
band.bandwidth = bandwidth
band.bypass = false
audioEngine.attach(playerNode)
audioEngine.attach(eqNode)
audioEngine.connect(playerNode, to: eqNode, format: format)
audioEngine.connect(eqNode, to: audioEngine.mainMixerNode, format: format)
let outputFile = try! AVAudioFile(forWriting: outputURL, settings: audioFile.fileFormat.settings)
audioEngine.mainMixerNode.installTap(onBus: 0, bufferSize: 4096, format: format) { (buffer, time) in
do {
try outputFile.write(from: buffer)
} catch {
completion(false, error)
}
}
audioEngine.prepare()
do {
try audioEngine.start()
} catch {
completion(false, error)
return
}
playerNode.scheduleFile(audioFile, at: nil) {
audioEngine.mainMixerNode.removeTap(onBus: 0)
audioEngine.stop()
completion(true, nil)
}
playerNode.play()
}
// 使用示例
let inputURL = URL(fileURLWithPath: "path/to/input/audio/file")
let outputURL = URL(fileURLWithPath: "path/to/output/audio/file")
let centerFrequency: Float = 1000.0 // 中心频率
let bandwidth: Float = 100.0 // 带宽
applyBandpassFilter(inputURL: inputURL, outputURL: outputURL, centerFrequency: centerFrequency, bandwidth: bandwidth) { success, error in
if success {
print("音频处理完成并保存成功")
} else {
print("音频处理失败: \(error?.localizedDescription ?? "未知错误")")
}
}
在这个示例中,我们使用 AVAudioEngine
来创建一个音频处理管道,并使用 AVAudioUnitEQ
来应用带通滤波器。我们通过 installTap
方法将处理后的音频数据写入到一个新的音频文件中。
请注意,你需要