设想
我通常使用MP3Gain应用程序来设置 mp3 文件的回放增益。
应用程序可以在 mp3 文件的APEv2标记中创建这些字段：
（截图取自WinAmp播放器）
问题
使用TagLibSharp库，我编写了一个ID3v1和ID3v2解析器，现在，我想知道我是否可以使用这个库读取和写入提到的APEv2字段？
研究
我认为MP3Gain应用程序对字段使用唯一名称，因此TagLibsharp可能不支持它们，但是，TagLibsharp库有我认为需要使用的 、 和 方法，但我不知道ReadBlock()具体如何Removeblock()使用他们一起...Find()RFind()
这是我唯一拥有的：
Dim file As New TagLib.Mpeg.AudioFile("C:\input.mp3")
Dim data As Byte() = Encoding.ASCII.GetBytes("MP3GAIN_MINMAX")
Dim vector As New ByteVector(data)
Dim offset As Long = file.Find(vector)
这是用 Vb.Net 编写的伪代码，只是为了演示预期的抽象或行为。
Imports TagLib
Public NotInheritable Class Mp3File
Private tagFile As Global.TagLib.Mpeg.AudioFile
Public ReadOnly Property APEv2 As APEv2Tag
Get
Return Me.apeTagB
End Get
End Property
Private ReadOnly apeTagB As APEv2Tag
Public Sub New(ByVal file As FileInfo)
Me.tagFile = New Global.TagLib.Mpeg.AudioFile(file.FullName)
Me.apeTagB = New APEv2Tag(Me.tagFile)
End Sub
End Class
''' <summary>
''' Represents the APEv2 tag for a MP3 file.
''' </summary>
Public Class APEv2Tag
Protected ReadOnly mp3File As Global.TagLib.Mpeg.AudioFile
Public Sub New(ByVal mp3File As Global.TagLib.Mpeg.AudioFile)
Me.mp3File = mp3File
End Sub
Public Overridable Property MP3GAIN_MINMAX As Double
Get
If field exists then...
Return TheValue...
End If
End Get
Set(ByVal value As Double)
...
End Set
End Property
' More properties here...
End Class
更新：
我认为我终于自己完成了“读取”部分，但是我不确定如何编写块，因为如果该字段不存在肯定我可以覆盖/损坏文件......
''' ----------------------------------------------------------------------------------------------------
''' <summary>
''' Gets the <c>MP3GAIN_MINMAX</c> metatada field of the audio file.
''' </summary>
''' ----------------------------------------------------------------------------------------------------
''' <returns>
''' The <c>MP3GAIN_MINMAX</c> field value.
''' </returns>
''' ----------------------------------------------------------------------------------------------------
<DebuggerStepThrough>
Private Function GetFieldMP3GainMinMax() As String
Dim data As Byte() = Encoding.UTF8.GetBytes("MP3GAIN_MINMAX")
Dim vector As New ByteVector(data)
Dim offset As Long = Me.mp3File.Find(vector)
Dim result As String
If (offset = -1) Then
Return String.Empty
Else
Try
offset += ("MP3GAIN_MINMAX".Length + 1)
Me.mp3File.Seek(offset, SeekOrigin.Begin)
result = Me.mp3File.ReadBlock(8).ToString.TrimEnd()
Return result
Catch ex As Exception
Throw
Finally
Me.mp3File.Seek(0, SeekOrigin.Begin)
End Try
End If
End Function
''' ----------------------------------------------------------------------------------------------------
''' <summary>
''' Gets the <c>MP3GAIN_UNDO</c> metatada field of the audio file.
''' </summary>
''' ----------------------------------------------------------------------------------------------------
''' <returns>
''' The <c>MP3GAIN_UNDO</c> field value.
''' </returns>
''' ----------------------------------------------------------------------------------------------------
<DebuggerStepThrough>
Private Function GetFieldMP3GainUndo() As String
Dim data As Byte() = Encoding.UTF8.GetBytes("MP3GAIN_UNDO")
Dim vector As New ByteVector(data)
Dim offset As Long = Me.mp3File.Find(vector)
Dim result As String
If (offset = -1) Then
Return String.Empty
Else
Try
offset += ("MP3GAIN_UNDO".Length + 1)
Me.mp3File.Seek(offset, SeekOrigin.Begin)
result = Me.mp3File.ReadBlock(12).ToString.TrimEnd()
Return result
Catch ex As Exception
Throw
Finally
Me.mp3File.Seek(0, SeekOrigin.Begin)
End Try
End If
End Function
''' ----------------------------------------------------------------------------------------------------
''' <summary>
''' Gets the <c>REPLAYGAIN_TRACK_GAIN</c> metatada field of the audio file.
''' </summary>
''' ----------------------------------------------------------------------------------------------------
''' <returns>
''' The <c>REPLAYGAIN_TRACK_GAIN</c> field value.
''' </returns>
''' ----------------------------------------------------------------------------------------------------
<DebuggerStepThrough>
Private Function GetFieldReplayGainTrackGain() As String
Dim data As Byte() = Encoding.UTF8.GetBytes("REPLAYGAIN_TRACK_GAIN")
Dim vector As New ByteVector(data)
Dim offset As Long = Me.mp3File.Find(vector)
Dim result As String
If (offset = -1) Then
Return String.Empty
Else
Try
offset += ("REPLAYGAIN_TRACK_GAIN".Length + 1)
Me.mp3File.Seek(offset, SeekOrigin.Begin)
result = Me.mp3File.ReadBlock(12).ToString.TrimEnd()
Return result
Catch ex As Exception
Throw
Finally
Me.mp3File.Seek(0, SeekOrigin.Begin)
End Try
End If
End Function
''' ----------------------------------------------------------------------------------------------------
''' <summary>
''' Gets the <c>REPLAYGAIN_TRACK_PEAK</c> metatada field of the audio file.
''' </summary>
''' ----------------------------------------------------------------------------------------------------
''' <returns>
''' The <c>REPLAYGAIN_TRACK_PEAK</c> field value.
''' </returns>
''' ----------------------------------------------------------------------------------------------------
<DebuggerStepThrough>
Private Function GetFieldReplayGainTrackPeak() As String
Dim data As Byte() = Encoding.UTF8.GetBytes("REPLAYGAIN_TRACK_PEAK")
Dim vector As New ByteVector(data)
Dim offset As Long = Me.mp3File.Find(vector)
Dim result As String
If (offset = -1) Then
Return String.Empty
Else
Try
offset += ("REPLAYGAIN_TRACK_PEAK".Length + 1)
Me.mp3File.Seek(offset, SeekOrigin.Begin)
result = Me.mp3File.ReadBlock(8).ToString.TrimEnd()
Return result
Catch ex As Exception
Throw
Finally
Me.mp3File.Seek(0, SeekOrigin.Begin)
End Try
End If
End Function