对python中Librosa的mfcc步骤详解

1.对语音数据归一化

如16000hz的数据，会将每个点/32768

2.计算窗函数：（*注意librosa中不进行预处理）

3.进行数据扩展填充，他进行的是镜像填充（"reflect")

如原数据为 12345 -》 填充为4的，左右各填充4 即：5432123454321 即：5432-12345-4321

4.分帧

5.加窗：对每一帧进行加窗，

6.进行fft傅里叶变换

librosa中fft计算，可以使用.net中的System.Numerics

MathNet.Numerics.IntegralTransforms.Fourier.Forward(FFT_frame, FourierOptions.Matlab) 计算，结果相同

7.mel计算（每一帧取20个特征点）

Imports System.Numerics
Imports MathNet.Numerics
Imports MathNet.Numerics.IntegralTransforms

Module mfcc_module

  Public Class Librosa

  End Class

  Dim pi As Double = 3.1415926535897931





  Public Function spectrum(fft_data(,) As Complex) As Double(,)
    Dim new_data(fft_data.GetLength(0) - 1, fft_data.GetLength(1) - 1) As Double


    For n = 0 To fft_data.GetLength(0) - 1
      ' Debug.Print("////////////////////////spectrum//////////////////")
      ' Debug.Print("////////////////////////spectrum//////////////////")
      For i = 0 To fft_data.GetLength(1) - 1
        new_data(n, i) = fft_data(n, i).MagnitudeSquared
        ' Debug.Write(new_data(n, i) & "  ")
      Next
    Next

    Return new_data

  End Function


  Public Function FFT(data As Double(,)) As Complex(,)

    Dim result(data.GetLength(0) - 1, 1024) As Complex
    '2049 加了一个 数组类型 0 开始
    Dim FFT_frame As Complex() = New Complex(data.GetLength(1) - 1) {}

    For n = 0 To data.GetLength(0) - 1
      For i As Integer = 0 To data.GetLength(1) - 1
        FFT_frame(i) = data(n, i)
      Next
      MathNet.Numerics.IntegralTransforms.Fourier.Forward(FFT_frame, FourierOptions.Matlab)

      For k = 0 To 1024
        result(n, k) = FFT_frame(k)
      Next

      'Debug.Print("fft **************")
      'For Each mem In FFT_frame
      '  Debug.Print(mem.ToString & "  ")
      'Next


    Next n



    Return result


  End Function

  Public Function _mfcc(dct_ As Double(,）, power_to_db_ As Double(,)) As Double(,)
    'dct 20,128
    'power_to_db 5,128
    'result = 20,5
    Dim result(dct_.GetLength(0) - 1, power_to_db_.GetLength(1) - 1) As Double
    Dim r1, r2 As Double
    For n = 0 To dct_.GetLength(0) - 1 '20
      For i = 0 To power_to_db_.GetLength(1) - 1 '5
        r2 = 0
        For k = 0 To dct_.GetLength(1) - 1 '128
          r1 = dct_(n, k) * power_to_db_(k, i)
          r2 = r2 + r1

        Next
        result(n, i) = r2
      Next
    Next

    Return result
  End Function

  Public Function Dct(n_filters As Integer, n_input As Integer) As Double(,)

    Dim t1 As Double = 2 * n_input

    Dim samples(n_input - 1) As Double
    Dim basis(n_filters - 1, n_input - 1） As Double

    Dim n As Integer = 1
    For i = 0 To n_input - 1
      samples(i) = n * pi / (2 * n_input)
      n = n + 2
    Next i

    For i = 0 To n_input - 1
      basis(0, i) = 1 / Math.Sqrt(n_input)
    Next
    For n = 1 To n_filters - 1
      For i = 0 To n_input - 1
        basis(n, i) = Math.Cos(n * samples(i)) * Math.Sqrt(2 / n_input)

      Next
    Next

    Return basis
  End Function


  '1e-10 = 0.0000000001
  Public Function power_to_db(S As Double(,), Optional ref As Double = 1, Optional admin As Double = 0.0000000001, Optional top_db As Double = 80) As Double(,)

    Dim result(S.GetLength(0) - 1, S.GetLength(1) - 1） As Double

    Dim log_spec As Double


    For n = 0 To S.GetLength(0) - 1
      For i = 0 To S.GetLength(1) - 1

        log_spec = 10 * Math.Log10(Math.Max(admin, S(n, i)))
        result(n, i) = log_spec - 10 * Math.Log10(Math.Max(admin, ref))
      Next
    Next



    'If top_db <> 0 Then
    '  For n = 0 To S.GetLength(0) - 1
    '    For i = 0 To S.GetLength(1) - 1
    '      'result(n, i) = Math.Max(result(n, i), result(n, i) - top_db)
    '    Next
    '  Next

    'End If

    Return result



  End Function



  Public Function melspectrogram(mel_basis(,) As Double, s(,) As Double) As Double(,)
    'mel_basis 128,1025
    's 5 ,1025 -> 1025,5
    ' result 128,5
    Dim result(mel_basis.GetLength(0) - 3, s.GetLength(0) - 1) As Double
    Dim r1, r2 As Double

    For n = 0 To mel_basis.GetLength(0) - 3

      For i = 0 To s.GetLength(0) - 1
        For k = 0 To mel_basis.GetLength(1) - 1


          r1 = mel_basis(n, k) * s(i, k)
          r2 = r2 + r1
        Next
        result(n, i) = r2
        r2 = 0
      Next

    Next
    Return result

  End Function

  Public Function normal(mel_f As Double(), weights(,) As Double) As Double(,)
    Dim enorm(mel_f.Length - 2) As Double

    ' Debug.Print("*************normal//////////////")
    ' Debug.Print("*************normal//////////////")
    For i = 0 To mel_f.Length - 3
      enorm(i) = 2 / (mel_f(2 + i) - mel_f(i))
    Next


    For i = 0 To weights.GetLength(1) - 1
      For n = 0 To weights.GetLength(0) - 2
        weights(n, i) = weights(n, i) * enorm(n)
      Next
    Next
    Return weights
  End Function


  Public Function weight(a As Double(,), fdiff As Double()) As Double(,)
    Dim lower, upper As Double

    Dim data(a.GetLength(0) - 1, a.GetLength(1) - 1) As Double

    For n = 0 To a.GetLength(0) - 3
      For i = 0 To a.GetLength(1) - 1
        lower = -(a(n, i) / fdiff(n))
        upper = a(n + 2, i) / fdiff(n + 1)
        data(n, i) = Math.Max(0, Math.Min(lower, upper))
      Next
    Next
    Return data
  End Function

  Public Function ramps(A As Double(), B As Double()) As Double(,)
    Dim data(A.Length - 1, B.Length - 1) As Double

    ' Debug.Print("ramps*********************")
    For n = 0 To A.Length - 1
      'Debug.Print("******")
      'Debug.Print("------")
      For i = 0 To B.Length - 1
        data(n, i) = A(n) - B(i)
        'Debug.Write(data(n, i) & "  ")
      Next
    Next
    Return data

  End Function
  Public Function diff(arr As Double()) As Double()
    Dim data(arr.Length - 2) As Double
    For i = 1 To arr.Length - 1
      data(i - 1) = arr(i) - arr(i - 1)
      'Debug.Print(data(i - 1))
    Next

    Return data
  End Function

  '分帧 算法2
  Public Function Frame2(y As Double(), Optional n_ftt As Integer = 2048, Optional hop As Integer = 512) As Double(,)
    Dim tim As Integer = Math.Floor((y.Length - n_ftt) / hop) + 1
    Dim new_buff(tim - 1, n_ftt - 1) As Double
    Dim copypos As Integer = 0
    For i = 0 To tim - 1
      For k = 0 To n_ftt - 1
        new_buff(i, k) = y(copypos + k)
      Next
      copypos = copypos + hop
    Next

    'For k = 0 To tim - 1
    '  Debug.Print("//////////////////////////////////////")
    '  Debug.Print("///////////////fram2///////////////////////" & k)
    '  For i = 0 To n_ftt - 1
    '    Debug.Print(new_buff(k, i) & " ")
    '  Next
    'Next k

    Return new_buff


  End Function

  '
  Public Function Frame(y As Double(), Optional n_ftt As Integer = 2048, Optional hop As Integer = 512) As Double()
    Dim tim As Integer = Math.Floor((y.Length - n_ftt) / hop) + 1
    Dim new_buff(tim * n_ftt) As Double
    Dim pos As Integer = 0
    Dim copypos As Integer = 0
    For i = 0 To tim - 1
      Array.Copy(y, copypos, new_buff, pos, n_ftt)
      'Buffer.BlockCopy(y, 0, new_buff, pos, n_ftt)
      copypos = copypos + hop
      pos = pos + n_ftt
    Next

    For k = 0 To tim - 1
      'Debug.Print("//////////////////////////////////////")
      'Debug.Print("//////////////////////////////////////")
      For i = 0 To n_ftt - 1
        Debug.Write(new_buff(k * n_ftt + i) & " ")
      Next
    Next k

    Return new_buff

  End Function


  Public Function MelFilter() As Double()
    Dim filter_points（128 + 1） As Integer '40个滤波器，需要41点
    Const sampleRate As Integer = 16000 '采样频率 16000
    Const filterNum As Integer = 128 '滤波器数量 取40个
    Const frameSize As Integer = 512 '帧长512

    Dim freMax As Double = sampleRate / 2  '实际最大频率
    Dim freMin As Double = 0  '实际最小频率
    Dim melFremax As Double = hz_to_mel(freMax)   '将实际频率转换成梅尔频率
    Dim melFremin As Double = 1125 * Math.Log(1 + freMin / 700)

    Dim k As Double = (melFremax - melFremin) / (filterNum + 1)

    Dim m As Double() = New Double(filterNum + 1) {}
    Dim h As Double() = New Double(filterNum + 1) {}

    For i As Integer = 0 To filterNum + 1
      m(i) = melFremin + k * i
      'h(i) = 700 * (Math.Exp(m(i) / 1125) - 1)
      '将梅尔频率转换成实际频率
      filter_points(i) = mel_to_hz(m(i))

      'Debug.Print(m(i))
    Next

    Dim hzs As Double() = mel_to_hz2(m)
    'For i = 0 To filterNum + 1
    '  ' Debug.Print(hzs(i))
    'Next
    Return hzs


  End Function

  Public Function hz_to_mel(frequencies As Double, Optional htk As Boolean = False) As Double

    Dim mels As Double

    If htk Then
      mels = 1125 * Math.Log(1 + frequencies / 700)
    Else
      Dim f_min As Double = 0.0
      Dim f_sp As Double = 200.0 / 3
      Dim min_log_hz As Double = 1000.0             ' beginning of log region (Hz)
      Dim min_log_mel As Double = (min_log_hz - f_min) / f_sp  ' same (Mels)
      Dim logstep As Double = Math.Log(6.4) / 27.0        ' step size for log region
      mels = min_log_mel + Math.Log(frequencies / min_log_hz) / logstep
    End If
    Return mels
  End Function

  Public Function mel_to_hz2(mel() As Double, Optional htk As Boolean = False) As Double()
    Dim hz(mel.Length - 1) As Double

    Dim f_min As Double = 0.0
    Dim f_sp As Double = 200.0 / 3
    Dim freqs(mel.Length - 1) As Double

    For i = 0 To mel.Length - 1
      freqs(i) = f_min + f_sp * mel(i)
    Next i

    Dim min_log_hz As Double = 1000.0             ' beginning of log region (Hz)
    Dim min_log_mel As Double = (min_log_hz - f_min) / f_sp  ' same (Mels)
    Dim logstep As Double = Math.Log(6.4) / 27.0

    For i = 0 To mel.Length - 1
      If (mel(i) > min_log_mel) Then
        freqs(i) = min_log_hz * Math.Exp(logstep * (mel(i) - min_log_mel))
      End If

    Next
    'hz = min_log_hz * Math.Exp(logstep * (mel - min_log_mel))


    Return freqs
  End Function

  Public Function mel_to_hz(mel As Double, Optional htk As Boolean = False) As Double
    Dim hz As Double
    If htk Then
      hz = 700 * (Math.Exp(mel) / 1125) - 1
    Else
      Dim f_min As Double = 0.0
      Dim f_sp As Double = 200.0 / 3
      Dim freqs = f_min + f_sp * mel

      Dim min_log_hz As Double = 1000.0             ' beginning of log region (Hz)
      Dim min_log_mel As Double = (min_log_hz - f_min) / f_sp  ' same (Mels)
      Dim logstep As Double = Math.Log(6.4) / 27.0
      hz = min_log_hz * Math.Exp(logstep * (mel - min_log_mel))
      'hz = min_log_hz * Math.Exp(logstep * (mel - min_log_mel))

    End If
    Return hz
  End Function


  Public Function fft_frequencies(sr As Integer, n_fft As Integer) As Double()
    Dim fft_data(n_fft / 2) As Double
    For i = 0 To n_fft / 2
      fft_data(i) = i * sr / n_fft
    Next
    Return fft_data
  End Function



  '左右填充，优化
  Public Function PadReflect2(data() As Double, num As Integer)
    'pad 10 ,10
    Dim tim(data.Length - 3) As Double
    For i = 0 To data.Length - 3
      tim(i) = data(data.Length - 2 - i)
    Next

    Dim dump() As Double = data.Concat(tim).ToArray()

    'For Each i In dump
    '  Debug.Write(i)
  End Function

  Public Function PadReflect(data() As Double, num As Integer)

    'pad 10 ,10
    Dim tim(data.Length - 3) As Double
    For i = 0 To data.Length - 3
      tim(i) = data(data.Length - 2 - i)
    Next

    Dim dump() As Double = data.Concat(tim).ToArray()

    'For Each i In dump
    '  Debug.Write(i)
    'Next

    'left_edge

    ' Debug.Print("***************************")
    Dim left_edge(num - 1) As Double
    _CopyDup(left_edge, dump, True)
    'For i = 0 To num - 1
    '  Debug.Write(left_edge(i))
    'Next

    'right_edge
    'Debug.Print("***************************")
    Dim right_edge(num + data.Length) As Double
    _CopyDup(right_edge, dump, False)
    'For i = 0 To num - 1
    '  Debug.Write(right_edge(i))
    'Next
    'Debug.Print("***************************")
    Dim result As Double() = left_edge.Concat(right_edge).ToArray()
    Return result

  End Function

  'copy tim to data dumply
  Public Function _CopyDup(data() As Double, tim() As Double, Optional left As Boolean = True)
    Dim last As Integer = data.Length Mod tim.Length
    Dim times As Integer = Math.Floor(data.Length / tim.Length)
    Dim pos As Integer
    If left Then
      Array.Copy(tim, tim.Length - last, data, 0, last)
      pos = last
      For i = 0 To times - 1
        Array.Copy(tim, 0, data, pos, tim.Length)
        pos = pos + tim.Length
      Next

    Else

      'RIGHT
      pos = 0
      For i = 0 To times - 1
        Array.Copy(tim, 0, data, pos, tim.Length)
        pos = pos + tim.Length
      Next

      Array.Copy(tim, 0, data, pos, last)

    End If


  End Function



  Public Function General_cosine(M As Integer, alpha As Double(), sym As Boolean) As Double()

    If Not sym Then
      M = M + 1
    End If


    Dim tim As Double = (2 * pi) / (M - 1)
    Dim x(M) As Double
    Dim w(M) As Double

    'Debug.Print("ine")
    For i = 0 To M - 1
      x(i) = -pi + tim * i
      'Debug.Write(x(i) & "  ")
    Next
    'Debug.Print("******")
    For i = 0 To alpha.GetLength(0) - 1
      For k = 0 To M - 1
        w(k) = w(k) + alpha(i) * Math.Cos(i * x(k))
        'Debug.Write(w(k) & "  ")
      Next

    Next

    Return w

  End Function

  ''' <summary>
  ''' 汉明窗
  ''' </summary>
  ''' <param name="M"> 窗长</param>
  ''' <returns></returns>
  Public Function General_hamming(M As Integer) As Double()
    Dim db As Double() = {0.5, 1 - 0.5}
    Return General_cosine(M, db, False)  '进行加1 ，若sys为false
  End Function

  Public Function Get_window(M As Integer) As Double()
    Return General_hamming(M)

  End Function



End Module

Imports System.IO
Imports System.Numerics
Imports TensorFlow

'Install-Package TensorFlowSharp

Public Class KeyWordDetect

  Dim graph As TFGraph
  Dim session As TFSession

  '加载模型
  Public Sub New()
    Dim model As Byte() = File.ReadAllBytes("f:\graph1.pb")
    '导入GraphDef

    graph = New TFGraph()
    graph.Import(model, "")

    session = New TFSession(graph)

    ' Threading.ThreadPool.SetMaxThreads(5, 5)
  End Sub

  Protected Overrides Sub finalize()

    session.CloseSession()


  End Sub

  '将声音数据变为mfcc byte数据
  Public Function DataBToMFCC(dataB() As Byte) As Double(,)
    Dim buff16(dataB.Length / 2 - 1) As Int16
    Buffer.BlockCopy(dataB, 0, buff16, 0, dataB.Length - 1)

    Dim result(,) As Double = MFCC(buff16)
    Return result
  End Function


  '将声音数据变为mfcc
  Public Function DataToMFCC(dataI() As Int16) As Double(,)

    Dim result(,) As Double = MFCC(dataI)
    Return result
  End Function


  '将mfcc变为输入数据格式
  Public Function MFCCToVect(mfcc As Double(,)) As Double(,,)
    Dim data(0, 1, 129) As Double

    Dim n As Integer = 0, m As Integer = 0
    For i = 0 To mfcc.GetLength(0) - 1
      For k = 0 To mfcc.GetLength(1) - 1
        data(0, m, n) = mfcc(i, k)
        n = n + 1
      Next
      If n = 130 Then

        m = 1
        n = 0
      End If
    Next
    Return data
  End Function

  Dim output
  Dim runner As TFSession.Runner
  Dim result
  Dim rshape

  '关键字检测
  Public Function Detected(Data(,,) As Double) As Double

    ' Dim tensor As TFTensor = New TFTensor(Data)
    runner = session.GetRunner()

    runner.AddInput(graph("input")(0), Data).Fetch(graph("out")(0))

    output = runner.Run()


    result = output(0)
    rshape = result.Shape
    Dim rt As Double
    rt = result.GetValue(True)(0)(0)
    'For k = 0 To rshape.GetValue(0) - 1
    '  rt = result.GetValue(True)(k)(0)
    '  'Debug.Print(rt)
    '  If (rt > 0.8) Then
    '    Debug.Print("-----------recogxili")
    '    ' MsgBox("recgo")
    '  End If
    'Next

    Return RT

  End Function



  'Public Function RunB(dataB() As Byte)
  '  Dim mfccd As Double(,) = DataBToMFCC(dataB)
  '  Dim inputx As Double(,,) = MFCCToVect(mfccd)
  '  Detected(inputx)
  'End Function


  'Public Function ThreadPoolRun(dataI() As Int16)

  '  Threading.ThreadPool.QueueUserWorkItem(Run(dataI), dataI)
  '  '  Dim thrd1 As New Threading.Thread(New Threading.ParameterizedThreadStart(AddressOf Run))
  '  ' thrd1.Start(dataI)
  'End Function
  'Delegate Function DelgRun(dataI() As Int16)
  'Public Function ThreadRun(dataI() As Int16)
  '  ' Dim drun As New DelgRun(AddressOf Run)

  '  Dim thrd1 As New Threading.Thread(New Threading.ParameterizedThreadStart(AddressOf Run))
  '  thrd1.Start(dataI)

  'End Function


  Public Function Run(dataI() As Int16) As Double
    ' Debug.Print("thread *****1")
    Dim mfccd As Double(,) = DataToMFCC(dataI)
    Dim inputx As Double(,,) = MFCCToVect(mfccd)
    Return Detected(inputx)
  End Function

  Public Function MFCC(buff16() As Int16) As Double(,)
    Dim datalen As Integer = buff16.Length * 2
    Dim double_buff(datalen / 2 - 1) As Double
    Dim len As Integer = datalen / 2
    Array.Copy(buff16, double_buff, len)

    '******************
    For i = 0 To double_buff.Length - 1
      double_buff(i) = double_buff(i) / 32768
      ' Debug.Print(double_buff(i))
    Next


    '汉明窗create
    Dim hann_window As Double() = Get_window(2048)
    'Debug.Print("--------------------------")
    'Debug.Print("hann_window**************")
    For Each i In hann_window
      'Debug.Print(i & "  ")
    Next

    'Debug.Print("--------------------------")
    'Debug.Print("*************pad reflect**************")
    Dim y As Double() = PadReflect(double_buff, 1024)
    ' Dim y As Double() = double_buff
    'For Each i In y
    '  'Debug.Print(i & "  ")
    'Next

    'Debug.Print("--------------------------")
    'Debug.Print("***************frame************")
    Dim frams As Double(,) = Frame2(y)

    Dim tim As Integer = frams.GetLength(0)

    'Debug.Print("--------------------------")
    'Debug.Print("**********hann * data**************")
    Dim hannData(tim - 1, 2047) As Double



    For n = 0 To tim - 1
      For i = 0 To 2048 - 1
        hannData(n, i) = frams(n, i) * hann_window(i)
        ' Debug.Print(hannData(i) & "  ")
      Next

    Next n


    '\\\\\\\\\\\\\\\\melspecture
    Dim specturm1(,) As Complex = FFT(hannData)


    'For i = 0 To specturm1.GetLength(0) - 1
    '  Debug.Print("--------------------------------------")
    '  Debug.Print("--------------------------------------")
    '  For k = 0 To specturm1.GetLength(1) - 1
    '    Debug.Print(specturm1（i, k).Real & "  " & specturm1(i, k).Imaginary)
    '  Next
    'Next

    Dim s As Double(,) = spectrum(specturm1)

    Dim fftfreqs() As Double = fft_frequencies(16000, 2048)
    'Debug.Print("***************fftfreqs*****************")
    'Debug.Print("***************fftfreqs*****************")
    'Debug.Print("fftfreqs.shape", fftfreqs.Length)
    'For i = 0 To fftfreqs.Length - 1
    '  'Debug.Write(fftfreqs(i) & "  ")
    'Next

    ''''''''''''''''mel * specturm1
    'Debug.Print("**************")
    'Debug.Print("****滤波器创建**********")
    Dim mel_f As Double() = MelFilter()


    'Debug.Print("--------------------------")
    'Debug.Print("hann_window**************")
    'Debug.Print("diff")
    Dim fdiff As Double() = diff(mel_f)

    Dim ramps_ As Double(,) = ramps(mel_f, fftfreqs)

    Dim weights(,) As Double = weight(ramps_, fdiff)

    normal(mel_f, weights)

    'S*WEIGHT = melspectrogram
    'weight 128,1025
    's 5 ,1025
    Dim melspectrogram_(,) As Double = melspectrogram(weights, s)
    Dim power_to_db_ As Double（,) = power_to_db(melspectrogram_)

    Dim dct_ As Double(,) = Dct(20, 128)

    Return _mfcc(dct_, power_to_db_)
  End Function

End Class

以上这篇对python中Librosa的mfcc步骤详解就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持服务器之家。

原文链接：https://blog.csdn.net/qq_39239990/article/details/80876250