VB3 How to Get or Create a Unique Audio CD Volume Label

 Last reviewed: January 9, 1997
Article ID: Q112768
The information in this article applies to:

- Standard and Professional Editions of Microsoft Visual Basic for 

  Windows, version 3.0

SUMMARY

Part of the Multimedia standard calls for all Audio CDs to have a unique volume identifier following a specific (suggested) format of: 

   XXXX-#####
XXXX is the alpha vendor code, and ##### is a five-digit unique number for the CD. This information is stored on the inner track of the CD and is also usually etched on the inner edge of the inside ring of the CD. Not all manufacturers have a unique volume identifier, nor do all follow this standard volume label format. Although this is a standard, at this time the MultiMedia Application Programming Interface (API) does not have a built-in function that will retrieve this information. This article shows you how to retrieve or create this information programmatically.

MORE INFORMATION

In order to retrieve the unique volume identifier from the CD, you need to call MSCDEX directly. The information on how to do this is contained within the MSCDEX 2.20 specification.

Because some manufacturers aren't including this unique identifier on their CDs, Microsoft recommends that you create a unique volume identifying number based on the track information already included on the CD. The following example shows you how.

Step-by-Step Example

This example shows a method for creating a unique number to identify an audio CD based on track information. The purpose of this number is to make it possible for Visual Basic programs to recognize a loaded CD and retrieve information from it.

  1. Start a new project in Visual Basic. Form1 is created by default.

  2. Add a text box (Text1) and an MCI control (MMControl1) to Form1.

  3. Place the following code in the Form_Load event of Form1: 

       Sub Form_Load ()
      Dim DiskID As Long
      Dim Track As Integer
      ' Initialize CD:
      mmcontrol1.DeviceType = "CDAudio"
      mmcontrol1.Command = "open"
      ' Make unique number based on tracks and tracklength:
      DiskID = mmcontrol1.Tracks
      For Track = 1 To mmcontrol1.Tracks
         mmcontrol1.Track = Track
         DiskID = DiskID + mmcontrol1.TrackLength  ' Add 4-byte TrackLength
         DiskID = DiskID + mmcontrol1.Length       ' Add 4-byte CD Length
      Next Track
      ' Set text to unique value:
      Text1.Text = DiskID
   End Sub

  4. Load a CD.

  5. Start the program, or press the F5 key.

  6. The Text1 box should have a unique identifying number for the CD.

NOTE: Before starting the program, a CD must be inserted and ready to play. Therefore, you should add code to detect when a CD has been inserted and then run the above code.

REFERENCES

For more information, see the MultiMedia Programmer's Reference, CDAudio

KBCategory: kbprg kbcode
KBSubcategory: PrgOther
Additional reference words: 3.00

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Last reviewed: January 9, 1997
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