iOS，通过AudioUnit从48K到16K的音频重采样

我一直在尝试使用AudioUnit或AudioConverterRef对我的实时PCM单声道、48000采样率到16000采样率单声道进行重新采样，但我在这两个方面都没有成功

我查看了以下资源，但没有发现它们有多大帮助

我使用AudioConverterRef的代码是

     var inputFormat = CAStreamBasicDescription(
        sampleRate: Double(Constants.SAMPLE_RATE),
        numChannels: 1,
        pcmf: .int16,
        isInterleaved: false
    )
    
    var outputFormat = CAStreamBasicDescription(
        sampleRate: Double(16000),
        numChannels: 1,
        pcmf: .int16,
        isInterleaved: false
    )
    
    status = AudioConverterNew(
            &inputFormat!,
            &outputFormat!,
            &converter48To16
    )
    
    if status != noErr {
        print("ERROR HERE: \(status)")
    }
    
    
    let outputBytes = outputFormat!.mBytesPerPacket * (640 * 1280 / inputFormat!.mBytesPerPacket)
    
    let outputBuffer = UnsafeMutablePointer<CChar>.allocate(capacity: Int(outputBytes))
    
    defer { outputBuffer.deallocate() }
    
    var outputBufferList = AudioBufferList()
    outputBufferList.mNumberBuffers = 1
    outputBufferList.mBuffers.mNumberChannels = 1
    outputBufferList.mBuffers.mDataByteSize = outputBytes
    outputBufferList.mBuffers.mData = UnsafeMutableRawPointer(outputBuffer)
    

    var outputDataPacketSize = outputBytes / outputFormat!.mBytesPerPacket
    
     status = AudioConverterFillComplexBuffer(
        converter48To16!,
        conversionAudioController_Callback,
        UnsafeMutableRawPointer(Unmanaged.passUnretained(self).toOpaque()),
        &outputDataPacketSize,
        &outputBufferList,
        nil
    )
    
    if status != noErr {
        print("ERROR HERE: \(status)")
    }

我在这行收到的错误是：

let delegate = unsafeBitCast(inAudioConverter, to: AudioUnitDataChannelCallbackDelegate.self)

线程1:EXC\u错误访问（代码=1，地址=0xdbd000）

我在设置属性时没有收到任何问题，但只在实际执行代码时收到错误

我目前正在以48000采样率录制PCM 16位单声道，并尝试将其采样率降至16000

问题更新：

 func performConversion(ioNumberDataPackets: UnsafeMutablePointer<UInt32>, ioData: UnsafeMutablePointer<AudioBufferList>, outDataPacketDescription: UnsafeMutablePointer<UnsafeMutablePointer<AudioStreamPacketDescription>?>?, inUserData: UnsafeMutableRawPointer?) -> OSStatus {
    
    let retained = inUserData!.assumingMemoryBound(to: AudioBufferList.self)

    let maxPackets = retained.pointee.mBuffers.mDataByteSize / 2
    if ioNumberDataPackets.pointee > maxPackets {
        ioNumberDataPackets.pointee = maxPackets
    }

    print("CONVERSION RUNNING...")

    let ioDataPtr = UnsafeMutableAudioBufferListPointer(ioData)
    ioDataPtr[0].mData = UnsafeMutableRawPointer(inputBufferList?.mBuffers.mData)
    ioDataPtr[0].mDataByteSize = 1280
    ioDataPtr[0].mNumberChannels = inputBufferList!.mBuffers.mNumberChannels

    print("ioDataPtr: \(ioDataPtr[0].mDataByteSize)")
    return noErr
}

func performConversion（ioNumberDataPackets:UnsafeMutablePointer，ioData:UnsafeMutablePointer，outDataPacketDescription:UnsafeMutablePointer？，inUserData:UnsafeMutableRawPointer？->OSStatus{
let retained=inUserData！.AssumingMemoryBind（到：AudioBufferList.self）
让maxPackets=retained.pointee.mBuffers.mDataByteSize/2
如果ioNumberDataPackets.pointee>maxPackets{
ioNumberDataPackets.pointee=maxPackets
}
打印（“正在运行转换…”）
让ioDataPtr=UnsafemutabalAudioBufferListPointer（ioData）
ioDataPtr[0].mData=UnsafemtableRawPointer（inputBufferList？.mBuffers.mData）
ioDataPtr[0]。mDataByteSize=1280
ioDataPtr[0]。mNumberChannels=inputBufferList！.mBuffers.mNumberChannels
打印（“ioDataPtr:\（ioDataPtr[0].mDataByteSize）”）
返回noErr
}

*************问题编辑：*************

记录数据和下采样48K至16K

 func performRecording(_ ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>, inTimeStamp: UnsafePointer<AudioTimeStamp>, inBufNumber: UInt32, inNumberFrames: UInt32, ioData: UnsafeMutablePointer<AudioBufferList>) -> OSStatus {
    
    print("*******************")
    var err: OSStatus = noErr
    
    err = AudioUnitRender(audioUnit!, ioActionFlags, inTimeStamp, 1, inNumberFrames, ioData)
    
    var monoSamples = [Int16]()
    
    let rawAudioPointer = ioData[0].mBuffers.mData?.bindMemory(to: Int16.self, capacity: Int(inNumberFrames))
    if rawAudioPointer == nil {
        return noErr
    }
    monoSamples.append(contentsOf: UnsafeBufferPointer(start: rawAudioPointer, count: Int(inNumberFrames)))
    
    inputBufferList = ioData.pointee
    
    let outputBuffer = UnsafeMutablePointer<CChar>.allocate(capacity: 684)
    defer { outputBuffer.deallocate() }
    
    var fillBufferList = AudioBufferList()
    fillBufferList.mNumberBuffers = 1
    fillBufferList.mBuffers.mNumberChannels = 1
    fillBufferList.mBuffers.mDataByteSize = 684
    fillBufferList.mBuffers.mData = UnsafeMutableRawPointer(outputBuffer)

    var ioOutputDataPackets: UInt32 = 384

    inputBufferList = ioData.pointee

    let status = AudioConverterFillComplexBuffer(
        converter48To16!,
        conversionAudioController_Callback,
        UnsafeMutableRawPointer(Unmanaged.passUnretained(self).toOpaque()),
        &ioOutputDataPackets,
        &fillBufferList,
        nil
    )

    if status != noErr {
        print("ERROR HERE CONVERSION: \(status)")
    }
    
    print("MONOSAMPLE DATA \(monoSamples.count) and \(ioOutputDataPackets) and \(fillBufferList.mBuffers.mDataByteSize)")
    
    return err
}

func performRecording（\ioActionFlags:Unsafemtablepointer，inTimeStamp:UnsafePointer，inBufNumber:UInt32，inNumberFrames:UInt32，ioData:Unsafemtablepointer）->OSStatus{
打印（“*******************”）
变量err:OSStatus=noErr
err=AudioUnitRender（audioUnit！、ioActionFlags、inTimeStamp、1、inNumberFrames、ioData）
var monoSamples=[Int16]（）
让rawAudioPointer=ioData[0].mBuffers.mData？.bindMemory（to:Int16.self，capacity:Int（inNumberFrames））
如果rawAudioPointer==nil{
返回noErr
}
append（contentsOf:UnsafeBufferPointer（start:rawAudioPointer，count:Int（inNumberFrames）））
inputBufferList=ioData.pointee
let outputBuffer=UnsafeMutablePointer.allocate（容量：684）
延迟{outputBuffer.deallocate（）}
var fillBufferList=AudioBufferList（）
fillBufferList.mNumberBuffers=1
fillBufferList.mBuffers.mNumberChannels=1
fillBufferList.mBuffers.mDataByteSize=684
fillBufferList.mBuffers.mData=UnsafemtableRawPointer（outputBuffer）
var ioOutputDataPackets:UInt32=384
inputBufferList=ioData.pointee
let status=AudioConverterFillComplexBuffer(
转换器48到16！，
conversionAudioController\u回调，
UnsafeMutableRawPointer（Unmanaged.passUnretained（self.toOpaque（）），
&ioOutputDataPackets，
&填充列表，
无
)
如果状态！=noErr{
打印（“此处转换错误：\（状态）”）
}
打印（“单样本数据\（monoSamples.count）和\（ioOutputDataPackets）和\（fillBufferList.mBuffers.mDataByteSize）”）
返回错误
}

---

录制没有问题，但当我的输出与mDataByteSize=684不匹配时，我会在此处得到错误转换：1768846202

您应该在

inUserData

上执行

未安全比特广播

，而不是

inAudioConverter

。是的，我将其更改为inUserData，但现在AudioConverterFillComplexBuffer线程1:EXC_断点（代码=1，子代码=0x1bc238ff4）出现错误。您能否显示

performConversion

并更新问题？我将更新我的问题。我已编辑了我的问题

 func performRecording(_ ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>, inTimeStamp: UnsafePointer<AudioTimeStamp>, inBufNumber: UInt32, inNumberFrames: UInt32, ioData: UnsafeMutablePointer<AudioBufferList>) -> OSStatus {
    
    print("*******************")
    var err: OSStatus = noErr
    
    err = AudioUnitRender(audioUnit!, ioActionFlags, inTimeStamp, 1, inNumberFrames, ioData)
    
    var monoSamples = [Int16]()
    
    let rawAudioPointer = ioData[0].mBuffers.mData?.bindMemory(to: Int16.self, capacity: Int(inNumberFrames))
    if rawAudioPointer == nil {
        return noErr
    }
    monoSamples.append(contentsOf: UnsafeBufferPointer(start: rawAudioPointer, count: Int(inNumberFrames)))
    
    inputBufferList = ioData.pointee
    
    let outputBuffer = UnsafeMutablePointer<CChar>.allocate(capacity: 684)
    defer { outputBuffer.deallocate() }
    
    var fillBufferList = AudioBufferList()
    fillBufferList.mNumberBuffers = 1
    fillBufferList.mBuffers.mNumberChannels = 1
    fillBufferList.mBuffers.mDataByteSize = 684
    fillBufferList.mBuffers.mData = UnsafeMutableRawPointer(outputBuffer)

    var ioOutputDataPackets: UInt32 = 384

    inputBufferList = ioData.pointee

    let status = AudioConverterFillComplexBuffer(
        converter48To16!,
        conversionAudioController_Callback,
        UnsafeMutableRawPointer(Unmanaged.passUnretained(self).toOpaque()),
        &ioOutputDataPackets,
        &fillBufferList,
        nil
    )

    if status != noErr {
        print("ERROR HERE CONVERSION: \(status)")
    }
    
    print("MONOSAMPLE DATA \(monoSamples.count) and \(ioOutputDataPackets) and \(fillBufferList.mBuffers.mDataByteSize)")
    
    return err
}