SAPI 5.1 in Creating Text to Speech Applications using C#
By ArunGG

SAPI 5 Overview:

The SAPI application programming interface (API) considerably decreases the code necessary for an application to use speech recognition and text-to-speech, making speech technology more handy and robust for a broad range of applications.

The SAPI API provides a high-level interface between an application and speech engines. SAPI implements all the low-level details needed to control and deal with the real-time operations of various speech engines.

The two fundamental types of SAPI engines are text-to-speech (TTS) systems and speech recognizers.

SAPI 5.1 supports OLE automation. That means languages other than C/C++ may now use SAPI for application development. The languages themselves require supporting OLE automation. Common languages which may be used comprises Visual Basic, C#, and JScript.

Now let us see how to use SAPI 5.1 in C#.

With the help of TlbImp.exe tool we can generate SpeechLib.dll file.

The Program:

namespace TTS
{
    using System;
    using System.WinForms;
    using System.Threading;
    using SpeechLib;

      public class Tts: System.WinForms.Form
    {

    private System.WinForms.Button button1;
    private System.WinForms.CheckBox checkBox1;
    private System.WinForms.Button SPEAK;
    private System.WinForms.TextBox textBox1;

        public Tts()
        {
            
            InitializeComponent();
        }

      
        public override void Dispose()
        {
            
        }

           private void InitializeComponent()
        {
            this.checkBox1 = new System.WinForms.CheckBox();
  this.SPEAK = new System.WinForms.Button();
  this.button1 = new System.WinForms.Button();
  this.textBox1 = new System.WinForms.TextBox();
  
  checkBox1.Location = new System.Drawing.Point(88, 280);
  checkBox1.Text = "Save To Wave.";
  checkBox1.Size = new System.Drawing.Size(112, 24);
  checkBox1.TabIndex = 2;
  checkBox1.BackColor = System.Drawing.Color.DodgerBlue;
  
  SPEAK.Location = new System.Drawing.Point(96, 96);
  SPEAK.BackColor = System.Drawing.Color.DodgerBlue;
  SPEAK.Size = new System.Drawing.Size(96, 24);
  SPEAK.TabIndex = 1;
  SPEAK.Text = "SPEAK";
  SPEAK.Click += new System.EventHandler(SPEAK_Click);

  button1.Location = new System.Drawing.Point(88, 72);
  button1.BackColor = System.Drawing.Color.DodgerBlue;
  button1.Size = new System.Drawing.Size(112, 24);
  button1.TabIndex = 3;
  button1.Text = "EXIT";
                button1.Click += new System.EventHandler(button1_Click);
  
  textBox1.Location = new System.Drawing.Point(40, 120);
  textBox1.Text = " ";
  textBox1.Multiline = true;
  textBox1.ForeColor = (System.Drawing.Color)System.Drawing.Color.FromARGB((byte)192, (byte)0, (byte)0);
  textBox1.TabIndex = 0;
  textBox1.Size = new System.Drawing.Size(216, 160);
  textBox1.BackColor = (System.Drawing.Color)System.Drawing.Color.FromARGB((byte)192, (byte)192, (byte)255);
  this.Text = "TEXT TO SPEECH APP _ ARUNGG";
  this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
  this.BackColor = (System.Drawing.Color)System.Drawing.Color.FromARGB((byte)128, (byte)128, (byte)255);
  this.ClientSize = new System.Drawing.Size(312, 349);
  
  
  this.Controls.Add(button1);
  this.Controls.Add(checkBox1);
  this.Controls.Add(SPEAK);
  this.Controls.Add(textBox1);


        }
       
        static void Main() 
        {
            Application.Run(new Tts());
        }

                private void SPEAK_Click(object sender, System.EventArgs e)
        {
   
   try 
   {
SpeechVoiceSpeakFlags SpFlags = SpeechVoiceSpeakFlags.SVSFlagsAsync;
SpVoice speech = new SpVoice();
if (checkBox1.Checked)
{
SaveFileDialog sfd = new SaveFileDialog();
sfd.Filter = "All files (*.*)|*.*|wav files (*.wav)|*.wav";
sfd.Title = "Save to a wave file";
sfd.FilterIndex = 2;
sfd.RestoreDirectory = true;
if (sfd.ShowDialog()== DialogResult.OK) 
{
SpeechStreamFileMode SpFileMode = SpeechStreamFileMode.SSFMCreateForWrite;
SpFileStream SpFileStream = new SpFileStream();
SpFileStream.Open(sfd.FileName, SpFileMode, false);
speech.AudioOutputStream = SpFileStream;
speech.Speak(textBox1.Text, SpFlags);
speech.WaitUntilDone(Timeout.Infinite);
SpFileStream.Close();
 }
    }
 else
  {
 speech.Speak(textBox1.Text, SpFlags);
  }
   }
 catch
  {
 MessageBox.Show("Speak error");
  }

        }

        private void button1_Click(object sender, System.EventArgs e)
        {
    this.Close();
        }
    }
}

Explanation:

* This TTS application demonstrates how to create a SpVoice object and how to use it to speak text and save it to a .wav file.

* Declare the SpVoice object. //SpVoice speech = new SpVoice();//

* Create a wave stream //SpFileStream SpFileStream = new SpFileStream();//

* Create a new .wav file for writing. //SpFileStream.Open(sfd.FileName, SpFileMode, false);//

* Set the .wav file stream as the output for the Voice object//speech.AudioOutputStream = SpFileStream;//

* Call the Speak method now will send the output to the .wav file. //speech.Speak(textBox1.Text, SpFlags);//

* Close the file //SpFileStream.Close();//