Visual Basic 1002005 [A Developers Notebook] [Electronic resources] نسخه متنی

3.8. Play Simple WAV Audio

Neither .NET 1.0 or .NET 1.1 provided a
managed way to play audio. This shortcoming is finally addressed in
.NET 2.0 with the new SoundPlayer class, which
allows you to play audio synchronously or asynchronously.

Note: Using the SoundPlayer class, you can play WAV files
without diving into the Windows API.

3.8.1. How do I do that?

You can instantiate a SoundPlayer object
programmatically, or you can add one to the component tray by
dragging it from the toolbox at design time. Once
you've created the SoundPlayer,
you need to point it to the sound content you want to play. You do
this by setting one of two properties:

SoundLocation

If you have a file path or URL that points
to a WAV file, specify this information in the
SoundLocation property.

Stream

If you have a
Stream-based object that contains WAV audio
content, use the Stream property.

Once you've set the Stream or
SoundLocation property, you need to tell
SoundPlayer to actually load the audio data by
calling the Load( ) or LoadAsync(
) method. The Load( ) method pauses your
code until all the audio is loaded into memory. On the other hand,
LoadAsync( ) carries out its work on another
thread and fires the LoadCompleted event once
it's finished and the audio's
available. Usually, you'll use Load() unless you have an extremely large audio file or it takes
a long time to read the whole audio file (for example, when
retrieving the audio over a slow network or Internet connection).

Finally, once the audio is available, you can call one of the
following methods:

PlaySync( )

Pauses your code until the audio playback
is finished.

Play( )

Plays the audio on another thread,
allowing your code to continue with other tasks and making sure that
your application's interface remains responsive.

PlayLooping( )

Similar to Play( ),
except that it loops the audio, repeating it continuously.

To halt asynchronous playback at any time, just call
Stop( ).

The following code snippet shows an example that plays a sample sound
synchronously:

Dim Player As New SoundPlayer( )
Player.SoundLocation = Application.StartupPath & "\mysound.wav"
Try
Player.Load( )
Player.PlaySync( )
Catch Err As Exception
' An error will occur here if the file can't be read
' or if it has the wrong format.
End Try

3.8.2. What about...

...other types of audio? Unfortunately, the
SoundPlayer can only play the WAV audio format. If
you want to play other types of multimedia, like

MP3 or
WMA files, you need to use a different solution, and there are no
managed classes to help you out.

Two options include:

Use COM
Interop to access the Quartz library, which is a part of DirectX. The
Quartz library allows you to play any file type supported by Windows
Media Player, including MP3, WMA, and video formats like MPEG and
AVI. For an example in C# code, refer to Microsoft's
sample project at http://msdn.microsoft.com/library/en-us/csref/html/vcwlkcominteroppart1cclienttutorial.asp

Use
the managed DirectX 9.0 libraries. You'll need to
install the DirectX client and SDK on the computer for this to work,
but it gives you a great deal of power, including the ability to
render three-dimensional graphics. See http://msdn.microsoft.com/library/en-us/directx9_m/directx/dx9intro.asp
for an introduction.