【发布时间】：2016-03-15 12:33:30
【问题描述】：
场景
我一般使用MP3Gain应用来设置mp3文件的回放增益。
应用程序可以在 mp3 文件的 APEv2 标签中创建这些字段：
（截图来自WinAmp播放器）
问题
使用 TagLibSharp 库我写了一个 ID3v1 和 ID3v2 解析器，现在，我想知道我是否可以读写上面提到的 APEv2 字段使用这个库？
研究
我认为 MP3Gain 应用程序使用唯一的字段名称，所以可能 TagLibsharp 不支持它们，但是，TagLibsharp 库有一个 @ 987654326@、Removeblock()、Find() 和RFind() 方法我认为是我需要使用的，但我不知道具体如何结合使用它们......
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，只是为了展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，我肯定会覆盖/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
【问题讨论】：
标签： c# .net vb.net mp3 taglib-sharp