The Multimedia Control's Command
Language
The Multimedia control supports its own miniature command language (although this
language is not nearly as robust as the Visual Basic language). The Multimedia control
accepts, in its Command property, one word commands that control whatever device is
currently playing. Table 14.6 describes each of the commands and their meanings.
Table 14.6. These commands form the multimedia control's Command property language.
Command |
Description |
Back |
Steps backward through the device's tracks. |
Close |
Closes the device. |
Eject |
Ejects the CD from the CD-ROM drive. |
Next |
Goes to the beginning of the next track (or to the beginning of the final track if the
last track is current). |
Open |
Opens the device. |
Pause |
Pauses the device. |
Play |
Plays the device. |
Prev |
Returns to the beginning of the current track. If used within three seconds of the
most recent Prev command, Prev returns to the beginning of the previous track (or to the
start of the first track if the first track is current). |
Record |
Initializes recording on the device. |
Save |
Saves the open device file. |
Seek |
Seeks backward or forward a track (programmers typically use Next or Prev instead of
Seek due to its directional ambiguity). |
Stop |
Stops the device. |
Step |
Steps forward through the device's tracks. |
As your application runs, when your code changes the value in the Command property to a
different property, the multimedia control responds accordingly.

Your users do not have to control the multimedia control's device. You can hide all the
control's buttons and, through the Command property, control the device with your
application's code.

Putting Together a CD Player
Now that you've been introduced to the multimedia control, you can use it to put
together an application very quickly. Start a new project and assign properties shown in
Table 14.7 to the application.
Table 14.7. Use these properties and values on the multimedia control form.
Control |
Description |
Form's Name |
frmCD |
Form's Caption |
CD Player |
Form's Height |
3600 |
Form's Width |
4800 |
Label #1's Name |
lblCD |
Label #1's Alignment |
2-Center |
Label #1's BorderStyle |
1-Fixed Single |
Label #1's Caption |
CD Player |
Label #1's Font style |
Bold |
Label #1's Font size |
18 |
Label #1's Height |
495 |
Label #1's Left |
1320 |
Label #1's Top |
480 |
Label #1's Width |
1935 |
Label #2's Name |
lblTrack |
Label #2's Alignment |
1-Right Justify |
Label #2's Caption |
Track: |
Label #2's Font style |
Bold |
Label #2's Font size |
12 |
Label #2's Height |
255 |
Label #2's Left |
1200 |
Label #2's Top |
2280 |
Label #2's Width |
1215 |
Label #3's Name |
lblTrackNum |
Label #3's Caption |
(blank) |
Label #3's Font style |
Bold |
Label #3's Font size |
12 |
Label #3's Height |
375 |
Label #3's Left |
2520 |
Label #3's Top |
2280 |
Label #3's Width |
615 |
Multimedia control Name |
mmcCD |
Multimedia control DeviceType |
CDAudio |
Once you've placed these controls, enter the code you see in Listing 14.3 to complete
the CD player application.
Listing 14.3. This code handles the CD player.
1: Private Sub Form_Load()
2: ' Open the CD
3: mmcCD.Command = "Open"
4: End Sub
5:
6: Private Sub Form_Unload(Cancel As Integer)
7: ' Clean up the multimedia control when done
8: mmcCD.Command = "Close"
9: End Sub
10:
11: Private Sub mmcCD_StatusUpdate()
12: ' Update the track number in the label
13: lblTrackNum.Caption = mmcCD.Track
14: End Sub
The application opens the CD-playing multimedia control when the form first
loads. Line 8 removes the CD player from memory right before the application ends (as with
files, you should close any multimedia device you open). Line 13 updates the track number
every time the CD's status changes. The value in the multimedia control's UpdateInterval
property specifies the interval between updates of the status (the default is 1000).
Figure 14.10 shows the running CD player. The application is simple, but it works! You
can hone the application so that the CD player has a way to exit the application through a
File|Exit menu option. You can also add error-checking
and notification, as described in the next section.
Figure 14.10
This CD player application takes very little effort and time to create.

Obviously, some buttons that are disabled, such as the Record button, are not needed at
all in this application. You can hide these buttons if you want to clean up the multimedia
control a bit.


You've not only mastered the multimedia control as a CD player, but you've almost
mastered the control for all other multimedia devices as well! You'll see in subsequent
sections that you'll deal with the multimedia control in almost the same way you did here,
no matter which multimedia device you want the multimedia control to mimic.
