SAPI

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Revision as of 06:36, 7 March 2013 by Nsunny (talk | contribs) (Sample code for eSpeak)
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What is it

SAPI stands for Speech Application Programming Interface, a Microsoft Windows API used to perform text-to-speech (TTS).

Use with FreePascal

Lazarus/FreePascal can use this interface to perform TTS. Source: forum post: [1]

On Windows Vista and above, you will run in trouble with the FPU interrupt mask (see [2]). The code dealing with SavedCW is meant to work around this.

uses
  ...,comobj;
var
  SavedCW: Word;
  SpVoice: Variant;
begin
  SpVoice := CreateOleObject('SAPI.SpVoice');
  // Change FPU interrupt mask to avoid SIGFPE exceptions
  SavedCW := Get8087CW;
  try
    Set8087CW(SavedCW or $4);
    SpVoice.Speak('hi', 0);
  finally
    // Restore FPU mask
    Set8087CW(SavedCW);
  end;

For the options available with SpVoice.Speak and other SpVoice methods see http://msdn.microsoft.com/en-us/library/ms723609(v=vs.85).aspx.

WARNING The Ole object created in above snippet will be destroyed automatically when the SpVoice variant goes out of scope. For larger texts the use of the asynchronous mode allows to keep your application reactive while speak is running. In that case it is especially important to control carefully the lifetime of the object and store it in a global or class variable. Destroying the object while speak is still running can cause crashes.

Changing the FPU interrupt mask can be done at any moment before loading the ole object and if your application is not using any floating point arithmetic there is no need to reset the FPU interrupt mask to its original value.

Windows alternatives

An alternative on Windows is to use espeak. eSpeak has 11 voices, (7 male and 4 female) and is cross platform supporting Windows, Mac and Linux. It also has many command line parameters which can be used to further improve the speech. When coding, an eSpeak installation can be used and a stand-alone option is available as well.

A simple example is given below:

uses sysutils

...

var
  ExePath,MyText:String;
begin
  ExePath := 'path\to\espeak\command_line\espeak.exe';
  MyText := 'Hello World!';

  ExecuteProcess(ExePath, ' --path='+ExePath+' "' + MyText + '"', []);

It can also be used with TProcess to work with no console window appearing and GUI interface for customizing parameters.

Linux/Unix alternatives

On Linux/Unix, there are some command line Text To Speech engines, that may also offer access via APIs. An example is the festival engine.

See Linux_Programming_Tips#Perform_text-to-speech_.28TTS.29_or_how_to_let_my_computer_speak

OSX alternatives

OSX has system wide text to speech functionality built in: VoiceOver. See LCL_Accessibility#Mac_OS_X_VoiceOver See here for code for using the say command to perform TTS: [3]