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我有应用程序通过网络从 opus 解码流音频到 pcm，输出数据是 PCM 16 位，我成功解码，但是当我尝试使用 AVAudioEngine 播放它失败时，我无法将采样率从 44100 更改为 48000作品生成。

这是我用来播放音频的代码的一部分

self.self.audioEngine  = AVAudioEngine()
self.player  = AVAudioPlayerNode() 
self.downMixer      = AVAudioMixerNode()

self.audioEngine!.attach(downMixer!)
self.audioEngine!.attach(player!)

 let format48KHzMono = AVAudioFormat.init(commonFormat: AVAudioCommonFormat.pcmFormatInt16 , sampleRate: 48000.0, channels: 1, interleaved: true)

self.audioEngine!.connect(downMixer!, to: audioEngine!.outputNode, format: format48KHzMono)//use new audio format
self.audioEngine!.connect(downMixer!, to: audioEngine!.mainMixerNode  , format: format48KHzMono)
self.audioEngine!.connect(player!, to: audioEngine!.outputNode , format: player!.outputFormat(forBus: 0))  

downMixer!.outputVolume = 0.0

audioEngine!.prepare()
try! audioEngine!.start()       
try! self.player?.play()

这是我将 pcm 数据转换为 AVAudioPCMBuffer 的方法

   func toPCMBuffer(data: NSData) -> AVAudioPCMBuffer {
        let audioFormat = AVAudioFormat(commonFormat: AVAudioCommonFormat.pcmFormatInt16 , sampleRate: 48000.0, channels: 1, interleaved: true)  // given NSData audio format
        let PCMBuffer = AVAudioPCMBuffer(pcmFormat: audioFormat!, frameCapacity: UInt32(data.length) / audioFormat!.streamDescription.pointee.mBytesPerFrame )
        PCMBuffer!.frameLength = PCMBuffer!.frameCapacity
        let channels = UnsafeBufferPointer(start: PCMBuffer?.int16ChannelData, count: Int(PCMBuffer!.format.channelCount))
        data.getBytes(UnsafeMutableRawPointer(channels[0]) , length: data.length)
        return PCMBuffer!
     }

在循环中我使用这个

if let decodedDataChunk = OpusKit.shared.decodeData(frame) {
 let pcmData:AVAudioPCMBuffer = self.toPCMBuffer(data: decodedDataChunk as NSData)                               
 self.player?.scheduleBuffer(pcmData)
}
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