Is it possible, using TagLibSharp, to remove a Lyrics3v2 tag from a MP3 file?

天涯浪子 提交于 2019-12-04 14:35:10
PeterCo

According to How to remove Lyrics3 v2 tag from id3? the answer is "No". You will find a workaround in the linked answer below.

I wrote this solution using taglibsharp:

' *************************************************************
' THIS CLASS IS PARTIALLY DEFINED FOR THIS STACKOVERFLOW ANSWER
' *************************************************************

Imports System.IO
Imports System.Text
Imports TagLib

''' <summary>
''' Represents the <c>Lyrics3</c> tag for a MP3 file.
''' </summary>
Public Class Lyrics3Tag

    Protected ReadOnly mp3File As Mpeg.AudioFile

    ''' <summary>
    ''' The maximum length for the <c>Lyrics3</c> block to prevent issues like removing a false-positive block of data.
    ''' <para></para>
    ''' Note that this is a personal attempt to prevent catastrophes, not based on any official info.
    ''' </summary>
    Private ReadOnly maxLength As Integer = 512 ' bytes

    Private Sub New()
    End Sub

    Public Sub New(ByVal mp3File As Mpeg.AudioFile)
        Me.mp3File = mp3File
    End Sub

    ''' <summary>
    ''' Entirely removes the <c>Lyrics3</c> tag.
    ''' </summary>
    <DebuggerStepThrough>
    Public Overridable Sub Remove()

        Dim initVector As New ByteVector(Encoding.UTF8.GetBytes("LYRICSBEGIN"))
        Dim initOffset As Long = Me.mp3File.Find(initVector, startPosition:=0)

        If (initOffset <> -1) Then

            ' The Lyrics3 block can end with one of these two markups, so we need to evaluate both.
            For Each str As String In {"LYRICS200", "LYRICSEND"}

                Dim endVector As New ByteVector(Encoding.UTF8.GetBytes(str))
                Dim endOffset As Long = Me.mp3File.Find(endVector, startPosition:=initOffset)

                If (endOffset <> -1) Then

                    Dim length As Integer = CInt(endOffset - initOffset) + (str.Length)
                    If (length < Me.maxLength) Then
                        Try
                            Me.mp3File.Seek(initOffset, SeekOrigin.Begin)
                            ' Dim raw As String = Me.mp3File.ReadBlock(length).ToString()
                            Me.mp3File.RemoveBlock(initOffset, length)
                            Exit Sub

                        Catch ex As Exception
                            Throw

                        Finally
                            Me.mp3File.Seek(0, SeekOrigin.Begin)

                        End Try

                    Else ' Length exceeds the max length.
                         ' We can handle it or continue...
                        Continue For

                    End If

                End If

            Next str

        End If

    End Sub

End Class

Example usage:

Dim mp3File As New Taglib.Mpeg.AudioFile("filepath")

Using lyrics As New Lyrics3Tag(mp3File)
    lyrics.Remove()
End Using
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