我想将音频文件标准化为最大。
为此,我使用以下代码:
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
对于几乎所有文件,它都可以正常工作,但是对于一个文件,最后一行失败。
iHighestDataValue是13445,iLowestDataValue是-21940。
我猜最后一行有问题。
这仅仅是由于VB6无法处理此(正确)计算而引起的错误,还是我引入了任何错误?
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
最佳答案
这是不正确的,因为它会产生大量的裁剪。
代替:
sngVolumeLevel = ((iHighestDataValue + (iLowestDataValue * -1)) / 2) / 32767
最好这样做:
If iHighestDataValue >= -iLowestDataValue Then
sngVolumeLevel = iHighestDataValue / 32767.
Else
sngVolumeLevel = iLowestDataValue / -32768.
End If
关于audio - 我的音频标准化代码正确吗?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41401577/