Ios Swift 3：使用AVCaptureAudioDataOutput分析音频输入

我正试图使用AVCaptureAudioDataOutput来分析音频输入，如前所述。这不是我自己能弄明白的东西，所以我复制了这个例子，但我有困难

Swift 3中的Xcode促使我做了一些更改。我在分配

samples

的行中遇到编译错误。Xcode表示，“无法使用类型为“（UnsafeMutableRawPointer？）的参数列表调用类型为“UnsafeMutablePointer”的初始值设定项”

以下是我修改后的代码：

func captureOutput(_ captureOutput: AVCaptureOutput!,
                    didOutputSampleBuffer sampleBuffer: CMSampleBuffer!,
                   from connection: AVCaptureConnection!){
    var buffer: CMBlockBuffer? = nil
    var audioBufferList = AudioBufferList(mNumberBuffers: 1,
                                          mBuffers: AudioBuffer(mNumberChannels: 1, mDataByteSize: 0, mData: nil))
    CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
        sampleBuffer,
        nil,
        &audioBufferList,
        MemoryLayout<AudioBufferList>.size,     // changed for Swift 3
        nil,
        nil,
        UInt32(kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment),
        &buffer
    )
    let abl = UnsafeMutableAudioBufferListPointer(&audioBufferList)
    var sum:Int64 = 0
    var count:Int = 0
    var bufs:Int = 0
    for buf in abl {
        let samples = UnsafeMutableBufferPointer<Int16>(start: UnsafeMutablePointer(buf.mData),  // Error here
                                                        count: Int(buf.mDataByteSize)/sizeof(Int16))
        for sample in samples {
            let s = Int64(sample)
            sum = (sum + s*s)
            count += 1
        }
        bufs += 1
    }
    print( "found \(count) samples in \(bufs) buffers, sum is \(sum)" )
}

func captureOutput（\captureOutput:AVCaptureOutput！，
didOutputSampleBuffer sampleBuffer:CMSampleBuffer！，
来自连接：AVCaptureConnection！）{
var缓冲区：CMBlockBuffer？=nil
var audioBufferList=audioBufferList（mNumberBuffers:1，
mbuffer:AudioBuffer（mNumberChannels:1，mDataByteSize:0，mData:nil））
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
样本缓冲区，
无
&音频缓冲列表，
MemoryLayout.size，//已更改为Swift 3
无
无
UInt32（kCMSampleBufferFlag_Audio BufferList_Assure16 ByteAlignment），
&缓冲区
)
设abl=UnsafemeutableAudioBufferListPointer（&audioBufferList）
变量和：Int64=0
变量计数：Int=0
变量bufs:Int=0
用于abl中的buf{
让samples=UnsafeMutableBufferPointer（开始：UnsafeMutablePointer（buf.mData））//此处出错
计数：Int（buf.mDataByteSize）/sizeof（Int16））
样品中的样品{
设s=Int64（示例）
总和=（总和+s*s）
计数+=1
}
bufs+=1
}
打印（“在\（bufs）缓冲区中找到\（计数）样本，总和为\（总和）”）
}

---

有人能告诉我如何修复此代码吗？

答案是我需要将

buf.mData

包装在

不透明指针中。i、 例如，在调用
unsafemtablebufferpointer（OpaquePointer（buff.mData））
时，更改

start: UnsafeMutablePointer(buff.mData)

到

以下是为Swift 3更新的完整代码：

    func captureOutput(_ captureOutput: AVCaptureOutput!,
                   didOutputSampleBuffer sampleBuffer: CMSampleBuffer!,
                   from connection: AVCaptureConnection!){
    var buffer: CMBlockBuffer? = nil
    var audioBufferList = AudioBufferList(mNumberBuffers: 1,
                                          mBuffers: AudioBuffer(mNumberChannels: 1, mDataByteSize: 0, mData: nil))
    CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
        sampleBuffer,
        nil,
        &audioBufferList,
        MemoryLayout<AudioBufferList>.size,
        nil,
        nil,
        UInt32(kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment),
        &buffer
    )
    let abl = UnsafeMutableAudioBufferListPointer(&audioBufferList)
    var sum:Int64 = 0
    var count:Int = 0
    var bufs:Int = 0
    for buff in abl {
        let samples = UnsafeMutableBufferPointer<Int16>(start: UnsafeMutablePointer(OpaquePointer(buff.mData)),
                                                        count: Int(buff.mDataByteSize)/MemoryLayout<Int16>.size)
        for sample in samples {
            let s = Int64(sample)
            sum = (sum + s*s)
            count += 1
        }
        bufs += 1
    }
    print( "found \(count) samples in \(bufs) buffers, RMS is \(sqrt(Float(sum)/Float(count)))" )
}

func captureOutput（\captureOutput:AVCaptureOutput！，
didOutputSampleBuffer sampleBuffer:CMSampleBuffer！，
来自连接：AVCaptureConnection！）{
var缓冲区：CMBlockBuffer？=nil
var audioBufferList=audioBufferList（mNumberBuffers:1，
mbuffer:AudioBuffer（mNumberChannels:1，mDataByteSize:0，mData:nil））
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
样本缓冲区，
无
&音频缓冲列表，
MemoryLayout.size，
无
无
UInt32（kCMSampleBufferFlag_Audio BufferList_Assure16 ByteAlignment），
&缓冲区
)
设abl=UnsafemeutableAudioBufferListPointer（&audioBufferList）
变量和：Int64=0
变量计数：Int=0
变量bufs:Int=0
对于abl中的buff{
让samples=UnsafeMutableBufferPointer（开始：UnsafeMutablePointer（OpaquePointer（buff.mData）），
计数：Int（buff.mDataByteSize）/MemoryLayout.size）
样品中的样品{
设s=Int64（示例）
总和=（总和+s*s）
计数+=1
}
bufs+=1
}
打印（“在\（bufs）缓冲区中找到\（计数）样本，RMS为\（sqrt（浮点（总和）/浮点（计数））））
}

这使编译器感到满意，而且似乎生成了合理的数字。
我正在录制视频，方法是使用CMSampleBufferGetImageBuffer从sampleBuffer获取图像，修改图像，然后将其写入视频。如何检查sampleBuffer是否为音频，然后将其写入assetWriter？@ChewieTheChorkie要检查sampleBuffer是否为音频，可以查看
连接的属性
输出
。像这样，
如果connection.output是AVCaptureAudioDataOutput{…}否则{//isVideo}
也许我会试试，但我通过运行AVAudioRecorder“修复”了它，然后在最后合并音频和视频。“那不好吗？”丘耶特霍基真是个有用的暗示！你找到更好的解决办法了吗？我也有同样的问题（在实时视频录制中尝试绘制多个上下文时没有音频输出）
    func captureOutput(_ captureOutput: AVCaptureOutput!,
                   didOutputSampleBuffer sampleBuffer: CMSampleBuffer!,
                   from connection: AVCaptureConnection!){
    var buffer: CMBlockBuffer? = nil
    var audioBufferList = AudioBufferList(mNumberBuffers: 1,
                                          mBuffers: AudioBuffer(mNumberChannels: 1, mDataByteSize: 0, mData: nil))
    CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
        sampleBuffer,
        nil,
        &audioBufferList,
        MemoryLayout<AudioBufferList>.size,
        nil,
        nil,
        UInt32(kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment),
        &buffer
    )
    let abl = UnsafeMutableAudioBufferListPointer(&audioBufferList)
    var sum:Int64 = 0
    var count:Int = 0
    var bufs:Int = 0
    for buff in abl {
        let samples = UnsafeMutableBufferPointer<Int16>(start: UnsafeMutablePointer(OpaquePointer(buff.mData)),
                                                        count: Int(buff.mDataByteSize)/MemoryLayout<Int16>.size)
        for sample in samples {
            let s = Int64(sample)
            sum = (sum + s*s)
            count += 1
        }
        bufs += 1
    }
    print( "found \(count) samples in \(bufs) buffers, RMS is \(sqrt(Float(sum)/Float(count)))" )
}