Wyo VB Lecture Notes

Objective #1 - Use sound.

• To play a sound clip in a VB program, you should include the following declaration statement for the method PlaySound in the general declarations area of your form (where you declare module-level variables).
  
  Private Declare Auto Function PlaySound Lib "winmm.dll" (ByVal lpszSoundName As String, ByVal hModule As Integer, ByVal dwFlags As Integer) As Integer
  
  You do not have to memorize or fully understand this statement but you should be aware of the need to have it in a program that plays sound in a VB program.
  
  At the point where you want an actual sound to play, you then use the PlaySound method with a call statement like this
  
  PlaySound("buzzer.wav", 0, 1)
  
  The path of the actual sound file must be included as the first parameter of the method. This statement only works if the audio file buzzer.wav is located in the same folder as the .exe executable file in your VB project. The exe file is usually stored in the bin folder. However, if you move the exe file or wish to save the sound file in another folder location, you must provide the exact file path to the audio file in the set of double quotes. However, for good style the sound file should be located in a folder named Sounds. So it's best to use this syntax:
  
  PlaySound(System.AppDomain.CurrentDomain.BaseDirectory() + "..\..\Sounds\buzzer.wav", 0, 1)
  
  where the System.AppDomain.CurrentDomain.BaseDirectory() method is used. This method causes VB to "figure out" what folder (also known as a directory) stores the exe executable file. The two dots in the path of the file mean "go up one level" in the folder hierarchy. From the perspective of the exe file you must go up one level of folders to get to the point where you would then double-click the sounds folder and then find the actual sound file named buzzer.wav. As of VB 2008, the Debug folder is considered to be the base directory for a project since it contains the exe file.
  
  The PlaySound method must be spelled with a capital P and a capital S. Otherwise it won't work correctly. There are many different types of audio files that can be used with computers. Sounds that are stored with the wav audio file format will work in VB. The filename of a wav file ends with the .wav file extension. Some other sound formats are supported but unfortunately the popular mp3 format cannot be used with the PlaySound method.
  
  
• In order to play mp3 files, you must add a Windows Media Player object to your program. See this Microsoft link or http://www.devasp.net/net/articles/display/304.html for instructions on using a Windows Media Player object. See the Player object API for details. The main steps are to first right-click the Toolbox and select Choose Items. Select the Windows Media Player control (Msdxm.ocx) under the COM tab. When the Windows Media Player control icon appears in the Toolbox, add an object to your form. Then use code like this in a button named btnPlay
  
  btnPlay.Enabled = False
  Application.DoEvents()
  Dim filename As String = Application.StartupPath
  filename = filename.Substring(0, filename.Length - 3)
  AxWindowsMediaPlayer1.AutoStart = False
  AxWindowsMediaPlayer1.Filename = filename & "test.wav"
  AxWindowsMediaPlayer1.Play()
  
  In the AxWindowsMediaPlayer1_EndOfStream method add the following line of code        btnPlay.Enabled = True

Objective #2 - Use text to speech.

• Visual Basic will read text in a computer voice. To do so you must first add a reference to the MS Speech Object Library. Click the menu command Project/Add Reference. Next, click the COM tab and then select the entry named "Microsoft Speech Object Library".
  
  
• Type the line of code    Imports SpeechLib    at the top of your form and declare a module variable with the statement
  
  Public WithEvents vox As New SpVoice
  
  
• Then use the statement
  
  vox.Speak("Hello how are you", SpeechVoiceSpeakFlags.SVSFPurgeBeforeSpeak)
  
  to make the computer say "Hello how are you".
  
  
• You can learn more at http://www.codeproject.com/KB/audio-video/TTSinVBpackage.aspx or by viewing a program in the Handout folder.
• You can use Notepad to create a Visual Basic script that uses text to speech on a computer that doesn't even have Visual Basic installed. By typing the code
  
  Dim message, sapi
  message = InputBox("Enter text", "Speak This")
  Set sapi = CreateObject("sapi.spvoice")
  sapi.Speak message
  
  and saving this file as "Speak.vbs" (select Save As Type: All Files). You can double-click that file to run the script.