swift – AVAudioEngine实时音频

我的第一个想法是将(处理后的)输入数据存储到AVAudioPCMBuffer对象中,然后让它由AVAudioPlayerNode播放,就像在我的演示类中所看到的那样：

import AVFoundation

class AudioIO {
    var audioEngine: AVAudioEngine
    var audioInputNode : AVAudioInputNode
    var audioPlayerNode: AVAudioPlayerNode
    var audioMixerNode: AVAudioMixerNode
    var audioBuffer: AVAudioPCMBuffer

    init(){
        audioEngine = AVAudioEngine()
        audioPlayerNode = AVAudioPlayerNode()
        audioMixerNode = audioEngine.mainMixerNode

        let frameLength = UInt32(256)
        audioBuffer = AVAudioPCMBuffer(PCMFormat: audioPlayerNode.outputFormatForBus(0),frameCapacity: frameLength)
        audioBuffer.frameLength = frameLength

        audioInputNode = audioEngine.inputNode

        audioInputNode.installTapOnBus(0,bufferSize:frameLength,format: audioInputNode.outputFormatForBus(0),block: {(buffer,time) in
            let channels = UnsafeArray(start: buffer.floatChannelData,length: Int(buffer.format.channelCount))
            let floats = UnsafeArray(start: channels[0],length: Int(buffer.frameLength))

            for var i = 0; i < Int(self.audioBuffer.frameLength); i+=Int(self.audioMixerNode.outputFormatForBus(0).channelCount)
            {
                // doing my real time stuff
                self.audioBuffer.floatChannelData.memory[i] = floats[i];
            }
            })

        // setup audio engine
        audioEngine.attachNode(audioPlayerNode)
        audioEngine.connect(audioPlayerNode,to: audioMixerNode,format: audioPlayerNode.outputFormatForBus(0))
        audioEngine.startAndReturnError(nil)

        // play player and buffer
        audioPlayerNode.play()
        audioPlayerNode.scheduleBuffer(audioBuffer,atTime: nil,options: .Loops,completionHandler: nil)
    }
}

但这远离实时而不是很有效率.任何想法或经验？没关系,如果你喜欢Objective-C或Swift,我很感谢所有的注释,评论,解决方案等.