Inside Macintosh: Sound /

Chapter 1 - Introduction to Sound on the Macintosh / Sound Reference

Routines / Generating and Stopping Speech

SpeakString

You can use the SpeakString function to have the Speech Manager read a text string.

FUNCTION SpeakString (s: Str255): OSErr;

s

The string to be spoken.

DESCRIPTION

The SpeakString function attempts to speak the Pascal-style text string contained in the string s. Speech is produced asynchronously using the default system voice. When an application calls this function, the Speech Manager makes a copy of the passed string and creates any structures required to speak it. As soon as speaking has begun, control is returned to the application. The synthesized speech is generated asynchronously to the application so that normal processing can continue while the text is being spoken. No further interaction with the Speech Manager is required at this point, and the application is free to release the memory that the original string occupied.

If SpeakString is called while a prior string is still being spoken, the sound currently being synthesized is interrupted immediately. Conversion of the new text into speech is then begun. If you pass a zero-length string (or, in C, a null pointer) to SpeakString, the Speech Manager stops any speech previously being synthesized by SpeakString without generating additional speech. If your application uses SpeakString, it is often a good idea to stop any speech in progress whenever your application receives a suspend event. (Note, however, that calling SpeakString with a zero-length string has no effect on speech channels other than the one managed internally by the Speech Manager for the SpeakString function.)

The text passed to the SpeakString function may contain embedded speech commands, which are described in the chapter "Speech Manager" in this book.

SPECIAL CONSIDERATIONS

Because the SpeakString function moves memory, you should not call it at interrupt time.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the SpeakString function are

Trap macro	Selector
_SoundDispatch	$0220000C

RESULT CODES

noErr	0	No error
memFullErr	-108	Not enough memory to speak
synthOpenFailed	-241	Could not open another speech synthesizer channel

SEE ALSO

For an example of how to read a text string using the SpeakString function, see "Generating Speech From a String" on page 1-32. See the chapter "Dialog Manager" in Inside Macintosh: Macintosh Toolbox Essentials for a complete description of event filter functions.