Option Explicit
Function TimeCode(ByVal Frames As Long) As String
TimeCode = Format((Frames \ 24) / 86400, "hh:mm:ss") & ":" & Format(Frames Mod 24, "00")
End Function
Function Frames(ByVal TimeCode As String) As Long
Dim TJn() As String
TJn = Split(TimeCode, ":")
Frames = Int(TimeSerial(TJn(0), TJn(1), TJn(2)) * 86400 + 0.5) * 24 + TJn(3)
End Function