Code Review Vol. 3.01 - WMEncode and DRM Walkthrough

Imports WMEncoderLib
Imports System.Windows.Forms
Imports System.IO


Module Module1
    Dim WithEvents Encoder As WMEncoder
    Dim glbQuitBool As Boolean = False
    Dim baseURL As String
    Dim DRMProfilePass As String = "XXX"
    Dim DRMProfile As String = "ExportProfile.drm"


    Sub Main()
       Init()
       SearchDir(baseURL)
    End Sub

    Sub Init()
      Dim sr As StreamReader = New StreamReader("baseLoc.ini")
      Dim line As String
      line = sr.ReadLine()
      sr.Close()
      baseURL = line
    End Sub

    Function DoEncode(ByVal sourceFile As String, ByVal outputFile As String, ByVal thisProfile As WMEncProfile2, ByVal fileType As String) As Boolean
 Try
     Encoder = New WMEncoder
     Dim SrcGrpColl As IWMEncSourceGroupCollection = Encoder.SourceGroupCollection
     Dim SrcGrp As IWMEncSourceGroup = SrcGrpColl.Add("SG_1")
     Dim newFile As IWMEncFile = Encoder.File

     If fileType = "video" Then
      Dim vidFile As IWMEncVideoSource = SrcGrp.AddSource(2)
      vidFile.SetInput(sourceFile)
     End If


     Dim audFile As IWMEncAudioSource = SrcGrp.AddSource(1)

Up until this point it's fairly standard WMEncoder SDK code - create a sourcegroup collection, create a sourcegroup, and add a video or audio source to the source group - but here we introduce the DRM element. It follows the same template

     Dim DRM As IWMDRMContentAuthor
     Dim DRMProColl As IWMDRMProfileCollection
     Dim tempDRMPro As IWMDRMProfile

     DRM = Encoder.EncoderDRMContentAuthor

     ' Retrieve the collection of DRM profiles.
     DRMProColl = DRM.DRMProfileCollection

     'First remove any DRM Profiles that may still linger 
     tempDRMPro = DRMProColl.Item(0)
     DRM.RemoveDRMProfile(tempDRMPro.ID)

     ' Import a DRM profile.
     DRM.ImportDRMProfile(DRMProfilePass, DRMProfile)
     
     DRMProColl = DRM.DRMProfileCollection
     Dim DRMPro As IWMDRMProfile
     DRMPro = DRMProColl.Item(0)

Essentially the DRM set up follows the same format as the Encoder, create a ProfileCollection, create a profile object which references the literal .drm profile file that I had exported from the DRM server. A DRMContentAuthor is pulled from the base WMEncoder object and everything is imported into that.

     ' Set the current DRM profile into the encoding session.
     Dim vKeyID As Object = "XXXXX
     DRM.SetSessionDRMProfile(DRMPro.ID, vKeyID)

     Dim newProfile As WMEncProfile2 = New WMEncProfile2
     audFile.SetInput(sourceFile)
     newFile.LocalFileName = outputFile
     newProfile = thisProfile

     ' newProfile.LoadFromFile(thisProfile)
     SrcGrp.Profile = newProfile
     Encoder.AutoStop = True
     Encoder.RemoteAdmin = True
     Encoder.PrepareToEncode(True)
     Encoder.Start()

     Dim x As Integer

For the longest time the code didn't work. Until I found out that I needed to put a slight wait before encoding. And even while its encoding down below inside the while loop it still needs a pause between each iteration to register events and change states when necessary.

     
     'HACK - needs this to actually work, bug in WM SDK
     For x = 0 To 30
       Application.DoEvents()
       x = x + 1
     Next


     While Encoder.RunState = WMENC_ENCODER_STATE.WMENC_ENCODER_RUNNING
       Dim temp = Encoder.RunState
       Dim y As Integer
       For y = 0 To 300
         y = y + 1
       Next
      Application.DoEvents()
     End While

     Encoder.Stop()
     Return True

 Catch ex As Exception
     Console.WriteLine(ex)
     Dim errFile As String = outputFile + ".error"
     File.Create(errFile)
     File.Delete(outputFile)
     Return False
 End Try

 Encoder = Nothing

    End Function

Here I grab the .drm file from the filesystem and load it into the WMEncProfile2 object.

    Function RetrieveProfile(ByVal nFile) As WMEncProfile2
 Try
     Dim BasicEdit As WMEncBasicEdit
     BasicEdit = New WMEncBasicEdit

     ' Specify the input, output, and configuration files.
     BasicEdit.MediaFile = nFile

     ' Retrieve the duration of the input file, in seconds.
     Dim lFileDur As Long
     lFileDur = BasicEdit.Duration / 1000

     ' Retrieve the profile used by the input file.
     Dim Pro As WMEncProfile2
     Pro = BasicEdit.Profile

     Return Pro
 Catch ex As Exception
     Console.WriteLine(ex)
 End Try


    End Function




And here is the engine - I essentially read the directory that was set aside as the publishing directory, where all raw files to be encoded and distributed were deposited, and encode and drm them.



 Sub SearchDir(ByVal dir)
    'Environment.CurrentDirectory
     Dim di As New DirectoryInfo(dir)
     ' Create an array representing the files in the current directory.
     Dim fi As FileInfo() = di.GetFiles()
     Dim tempFile As FileInfo
     For Each tempFile In fi
       Dim currentProfile As WMEncProfile2
       Dim currentSourceFile As String = baseURL + "\" + tempFile.Name
       Dim currentOutputFile As String = baseURL + "\DRMed\" + tempFile.Name  
       Dim currentFType As String
       Dim currentFTypeArr = Split(tempFile.Name, ".")
       If currentFTypeArr(1) = "wma" Then
          currentFType = "audio"
       ElseIf currentFTypeArr(1) = "wmv" Then
          currentFType = "video"
       End If

       currentProfile = RetrieveProfile(currentSourceFile)
       DoEncode(currentSourceFile, currentOutputFile, currentProfile, currentFType)
     Next tempFile

 End Sub


End Module

And that's it. Pretty straightforward, but by automating the encoding process and combining it with the DRMing process I was anble to integrate that into the automated workflow that I was building as the infrastructure to the overall Music Choice broadband product.