我想录制音频文件并通过应用一些效果来保存它。录音还可以,播放此音频效果也不错。问题是,当我尝试将此类音频保存为脱机时,它会生成空音频文件。这是我的代码:
let effect = AVAudioUnitTimePitch()
effect.pitch = -300
self.addSomeEffect(effect)
func addSomeEffect(_ effect: AVAudioUnit) {
try? AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayAndRecord, with: .defaultToSpeaker)
let format = self.audioFile.processingFormat
self.audioEngine.stop()
self.audioEngine.reset()
self.audioEngine = AVAudioEngine()
let audioPlayerNode = AVAudioPlayerNode()
self.audioEngine.attach(audioPlayerNode)
self.audioEngine.attach(effect)
self.audioEngine.connect(audioPlayerNode, to: self.audioEngine.mainMixerNode, format: format)
self.audioEngine.connect(effect, to: self.audioEngine.mainMixerNode, format: format)
audioPlayerNode.scheduleFile(self.audioFile, at: nil)
do {
let maxNumberOfFrames: AVAudioFrameCount = 8096
try self.audioEngine.enableManualRenderingMode(.offline,
format: format,
maximumFrameCount: maxNumberOfFrames)
} catch {
fatalError()
}
do {
try audioEngine.start()
audioPlayerNode.play()
} catch {
}
let outputFile: AVAudioFile
do {
let url = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("temp.m4a")
if FileManager.default.fileExists(atPath: url.path) {
try? FileManager.default.removeItem(at: url)
}
let recordSettings = self.audioFile.fileFormat.settings
outputFile = try AVAudioFile(forWriting: url, settings: recordSettings)
} catch {
fatalError()
}
let buffer = AVAudioPCMBuffer(pcmFormat: self.audioEngine.manualRenderingFormat,
frameCapacity: self.audioEngine.manualRenderingMaximumFrameCount)!
while self.audioEngine.manualRenderingSampleTime < self.audioFile.length {
do {
let framesToRender = min(buffer.frameCapacity,
AVAudioFrameCount(self.audioFile.length - self.audioEngine.manualRenderingSampleTime))
let status = try self.audioEngine.renderOffline(framesToRender, to: buffer)
switch status {
case .success:
print("Write to file")
try outputFile.write(from: buffer)
case .error:
fatalError()
default:
break
}
} catch {
fatalError()
}
}
print("Finish write")
audioPlayerNode.stop()
audioEngine.stop()
self.outputFile = outputFile
self.audioPlayer = try? AVAudioPlayer(contentsOf: outputFile.url)
}
AVAudioPlayer无法使用输出URL打开文件。我通过文件系统查看了该文件,它是空的,无法播放。
为AVAudioSession选择不同的类别也不起作用。
感谢帮助!
UPDATE
我切换到输出文件中的记录中使用.caf文件扩展名,它工作正常。知道为什么.m4a不起作用吗?
你需要nil
outputFile
来刷新标题并关闭m4a文件。