Question

我想将音频文件规范化为最大值。

为此，我正在使用此代码：

Dim iHighestDataValue As Integer
Dim iLowestDataValue As Integer

Dim i&
For i = 1 To dc.wavedatasize / 2
    Get #iFile, , DataValue(i) ' reads data value into array

    If DataValue(i) > iHighestDataValue Then
        iHighestDataValue = DataValue(i)
    End If

    If DataValue(i) < iLowestDataValue Then
        iLowestDataValue = DataValue(i)
    End If
Next

Dim sngVolumeLevel As Single
sngVolumeLevel = ((iHighestDataValue + (iLowestDataValue * -1)) / 2) / 32767

它适用于几乎所有文件，但对于一个文件，最后一行失败。

iHighestDataValue为13445，iLowestDataValue为-21940。

我猜最后一行出了点问题。它只是VB6发生的错误，因为它无法处理这个（正确的）计算，或者我是否引入了任何错误？

当我将最后一行放入单独的计算中时，它可以正常工作：

Dim sngHighest As Single
If iHighestDataValue > 32767 Then
    sngHighest = 32767
Else
    sngHighest = iHighestDataValue
End If

Dim sngLowest As Single
If iLowestDataValue < -32767 Then
    sngLowest = -32767
Else
    sngLowest = iLowestDataValue
End If
sngLowest = sngLowest * -1

Dim sngVolumeLevel As Single
sngVolumeLevel = (sngHighest + sngLowest) / 2
sngVolumeLevel = (sngVolumeLevel / 32767)

谢谢！

PS：这是函数的最后一个标准化部分：

Dim tem As Long

For i = 1 To dc.wavedatasize / 2
    tem = CLng(DataValue(i) * 1 / sngVolumeLevel)
    If tem > 32767 Then
        tem = 32767 ' prevents integer overflow error
    End If
    If tem < -32767 Then
        tem = -32767 ' prevents integer overflow error
    End If
    DataValue(i) = CInt(tem) ' changes data value
Next i

wh.riffdatasize = dc.wavedatasize + Len(wh) + Len(wf) 'Riff chunk size may be different
' beacause some input wave files may contain information chunk which is not written in output file

iFile = FreeFile

Kill uPath 'Delete the original / source file. We will overwrite it with the normalized version of this file

Open uPath For Binary As #iFile
Put #iFile, , wh ' writes the wave header
Put #iFile, , wf ' writes wave format
Put #iFile, , dc ' writes the 8 byte string "data" and wave dataa size

For i = 1 To dc.wavedatasize / 2
    Put #iFile, , DataValue(i) ' writes data value in ouput file
Next i

Close #iFile

Answer 1

它不正确，因为它会产生大量的削波。

而不是：

segmentedControl.addTarget(self, action: #selector(self.mapTypeChanged(_:)), forControlEvents: . valueChanged)

最好这样做：

sngVolumeLevel = ((iHighestDataValue + (iLowestDataValue * -1)) / 2) / 32767

我的音频规范化代码是否正确？

1 个答案: