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我想从 iphone 麦克风录制并转换为 ulaw 格式的流数据，我猜那是 pcm 数据，但我有噪音。

installTap buff是什么音频格式？如何获得 ulaw 数据格式？我可以从 AVAudioRecorder 得到它，但我不会得到一个文件。更改格式设置 'AVFormatIDKey=kAudioFormatULaw' 会崩溃。

    func testMicrophoneRecording1 () throws {
        let tapNode: AVAudioNode = mixerNode
        let format = tapNode.outputFormat(forBus: 0)
       
        tapNode.installTap(onBus: 0, bufferSize: 1024, format: format, block: {
            (buffer, time) in
            let d = buffer.toNSData() as Data  
            let ulaw_data = convert_pcm_(to_ulaw: d) 
            sendUlawDataToDevice(data: ulaw_data)           
        })

        try engine.start()
    }

和连接是：

 func makeConnections() {
        let inputNode = engine.inputNode
        let inputFormat = inputNode.outputFormat(forBus: 0)
        engine.connect(inputNode, to: mixerNode, format: inputFormat)

        let mainMixerNode = engine.mainMixerNode
        let mixerFormat = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: 44100, channels: 1, interleaved: true)
        engine.connect(mixerNode, to: mainMixerNode, format: mixerFormat)
    }
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1 回答 1

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我从麦克风中得到 pcm 并转换为 ulaw，形成这个例子： https ://github.com/Epskampie/ios-coreaudio-example

于 2021-02-07T02:01:10.883 回答