BBC BASIC Programmers' Reference

Speech synthesis (LBB)

by Richard Russell, November 2015

The program below illustrates the use of the speak sub; it is compatible with both LB and LBB. Note that it is necessary to declare speechInit as global:

     ' LB speech synthesis without a helper DLL!
     ' by Richard Russell, 26-Mar-2012
 
     open "ole32.dll" for dll as #ole32
     calldll #ole32, "CoInitialize", 0 as long, r as long
     global speechInit
     do
       read phrase$
       print phrase$
       call speak phrase$
     loop until phrase$ = ""
     calldll #ole32, "CoUninitialize", r as long
     close #ole32
     end
 
     data "This is a demonstration of speech synthesis"
     data "using Liberty BASIC code without a helper DLL"
     data ""
 
     ' Text-to-speech subroutine, using the SAPI5 speech engine, by Richard Russell
 
     sub speak text$
 
     if speechInit = 0 then
       struct clsid, a as long, b as long, c as long, d as long
       clsid.a.struct = hexdec("96749377") : clsid.b.struct = hexdec("11D23391")
       clsid.c.struct = hexdec("C000E39E") : clsid.d.struct = hexdec("9673794F")
 
       struct iid, a as long, b as long, c as long, d as long
       iid.a.struct = hexdec("6C44DF74") : iid.b.struct = hexdec("499272B9")
       iid.c.struct = hexdec("99EFECA1") : iid.d.struct = hexdec("D422046E")
 
       struct voice, v as long
       struct temp, v as long
       calldll #ole32, "CoCreateInstance", clsid as struct, 0 as long, 5 as long, _
                                           iid as struct, voice as struct, r as long
       if voice.v.struct = 0 then notice "SAPI5 is not available" : end
       speechInit = 1
     end if
 
     length = len(text$)+1
     wtext$ = space$(length*2)
     calldll #kernel32, "MultiByteToWideChar", 0 as long, 0 as long, text$ as ptr, _
                        -1 as long, wtext$ as ptr, length as ulong, r as long
 
     pvoice = voice.v.struct
     temp.struct = pvoice
     pspeak = temp.v.struct + 80
     temp.struct = pspeak
     speak = temp.v.struct
     temp.struct = pvoice
 
     calldll #user32, "CallWindowProcA", speak as long, pvoice as long, _
                      wtext$ as ptr, 0 as long, 0 as long, r as long
     end sub

The default voice is used; it may be a male or female voice depending on the version of Windows. If you prefer to specify the gender (assuming both a male and a female voice are installed, which may not always be the case) you can insert 'tags' in the string to achieve that:

     data "<voice optional='gender=female'>This is a demonstration of speech synthesis</voice>"
     data "<voice optional='gender=male'>using Liberty BASIC code without a helper DLL</voice>"
     data ""

It is also possible to control the speed and the volume in a similar way:

     data "<rate absspeed = '4'>This is a demonstration of speech synthesis</rate>"
     data "<volume level = '50'>using Liberty BASIC code without a helper DLL</voice>"
     data ""

The speed should be specified as a value between -10 and +10, and the volume as a value between 0 and 100.

This alternative format for the tags may also be used:

     data "<rate absspeed = '4'/>This is a demonstration of speech synthesis"
     data "<volume level = '50'/>using Liberty BASIC code without a helper DLL"
     data ""

If you want to select a specific SAPI5 voice (and you know it is installed on your PC) you can do that as follows:

     data "<voice required='name=IVONA 2 Brian OEM'>This is a demonstration of speech synthesis</voice>"

In this case the voice selected is Ivona Brian (a British English male voice) which can be purchased from http://www.textaloud.com/