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TAPI and SAPI Speech
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Microsoft's Telephony API (TAPI) provides developers with a
standardized interface to a rich selection telephony hardware. By utilizing
TAPI,
developers can write applications that support any device with a TAPI
driver, also called a Telephony Service Provider (TSP). TAPI eliminates the need for developers to wrestle with device
specific APIs and enables well-behaved device sharing between TAPI
applications. Unfortunately TAPI is very complex and does not include
direct support for useful speech technologies like text-to-speech (TTS)
and speech recognition (SR). There is an entirely different
specification to address these needs called the Microsoft Speech API (SAPI).
We put both of these technologies together for you. |
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ExceleTel TeleTools
makes adding TAPI telephony functionality to your applications quick and
easy. In the folowing pages we've been able to put
together a fairly comprehensive guide to incorporating speech into
your application using Microsoft's SAPI Speech SDK 5.1. In addition,
we are developing of sample programs in various development environments
to help show you exactly how to do it yourself.
To create an application the utilizes ExceleTel TeleTools (TAPI) and
also uses SAPI you can write directly to SAPI or utilize a set of tools.
Listed below you will find links to other sources to learn more.
| NOTE
: Not all
telephony devices support Microsoft's SAPI. Please contact your telephony device provider for
more information. In addition, ExceleTel cannot provide free
support for Microsoft's SAPI. We provide the information and
sample found here purely as a resource to help our clients in
their search to build better applications.
In addition,
Microsoft has released SAPI 5.2, but only with Windows 2003
server. There are no plans by them to release this in a
standalone version. Our tests indicate that the samples work fine
on machines with SAPI 5.2. However, SAPI 5.2 is designed to
support the Microsoft Speech Server and Microsoft Speech
Application SDK only - there isn't currently a SAPI 5.2 SDK to
support development of standalone applications.
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This guide will cover the following topics:
- How the SAPI Speech SDK works
- How to install everything you need in several development
environments
- How to use SAPI speech with TeleTools to create speech enabled
programs
- How to simplify using wave files in various formats in your
application
- How our events, methods and properties make it easy for you
What are some of the things you can do with TeleTools, TAPI and SAPI
together? Well, you can create applications like call centers, CTI,
Interactive Voice Response (IVR), messaging, call answering, voicemail and
much more.
Text-To-Speech (TTS)
Text to speech technology works by breaking up all the sounds of the
spoken language into "phenomes", or the basic sounds that
make up all human speech like "eh", "ah",
"oh", "ow", and many others and putting them
together to form words. A lexicon inside a speech engine, such as
the one that Microsoft includes in their free SAPI SDK, knows how to take
words and pronounce them over a device with sound capability. It
uses the standard Windows multimedia sound capabilities. If a word
is not in the list or doesn't follow a standard rule of pronunciation,
SAPI incorporates XML (Extensible Markup Language) so that you can use
HTML like tags to tell it how to pronounce anything you like. You
can also use XML to control spoken volume,
speed and a number of other factors all on the fly. More on this
later.
The code to do Text-To-Speech can be as simple as this:
VB...
etRecord.DeviceID = etLine1.WavePlayID
'use TeleTools to get output device
SpMMAudioOut1.DeviceID = etRecord1.DeviceID
SpVoice1.AllowAudioOutputFormatChangesOnNextSet = False
SpVoice1.AudioOutputStream.Format.Type = SAFT8kHz16BitMono
Set SpVoice1.AudioOutputStream = SpMMAudioOut1
SpVoice1.Speak "This text speaks", SVSFlagsAsync
Delphi..
etRecord1.Device.ID := etLine1.WavePlay.ID; //TeleTools
sets up your audio
SpMMAudioOut1.DeviceId := etRecord1.Device.ID;
SpVoice1.AllowAudioOutputFormatChangesOnNextSet := False;
SpVoice1.AudioOutputStream.Format.type_ := SAFT8kHz16BitMono);
Spvoice1.AudioOutputStream := SpMMAudioOut1.DefaultInterface;
SpVoice1.Speak("This text speaks", SVSFlagsAsync).
If you are ready to jump in without any further tutorial, here are
links to our sample programs and to other sources on the web for
information and tools. If you are more interested in finding out how
it all fits together exactly how you can build your own application then
please follow along with this guide by clicking HERE
or on the link at the bottom of the page.
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ExceleTel
TTS sample programs
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Description |
| etTTSSimple |
A simple Text-To-Speech sample that
shows how to play speech over a phone line. etTTSSimple
allows you to select a TAPI line device, choose a wave file format
and play speech over a phone line during a connected call or over
your sound card. |
| etTextToSpeech
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A much more involved
sample than etTTSSimple that in addition to the above, shows how to change voices, speed,
and inflection with Extensible Markup Language (XML). You can start, stop,
pause, and use the tokens feature of SAPI. Place outgoing
calls or incoming calls, press DTMF digits and have the TTS voice
speak them back to you. |
| more
samples |
We have many other
samples that you can learn from and combine into any type of
telephony program. Click on the link to learn more |
The following are a few companies that may help you add SR and TTS to
your TeleTools TAPI application. Please note that we have no affiliation
with any of these companies and list them here just as a resource for you
to help you in your research:
| Links
to more information
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Maker of Chant Developer Workbench and Chant SpeechKit
CDLL, ActiveX, COM, Java, .Net and VCL SAPI components |
| Out &
About Productions
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Maker of DTalk, a SAPI speech recognition library
written in Delphi as a VCL and available as an ActiveX |
| Microsoft
Speech
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Microsoft's Speech Technologies WEB page discussion
.NET and SAPI |
| Microsoft
SAPI Speech Technology Group
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Online documentation for the SAPI spec including
ActiveX controls, COM objects, and more can be found HERE |
| Microsoft
3rd Party SAPI Support
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Other sources of products and tools that support MS
Speech |
| AT&T
Voice Engine
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Don't like a robot sounding voice? Very cool
interactive demo letting you hear what somebody who knows how to
write a speech engine can do with voice quality. |
| Digalo
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Another speech engine vendor offering an inexpensive speech engine
and multiple languages |
| Elan
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Hi-Quality speech engines and language support |
| Lernout
& Hauspie (Scansoft)
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The speech conglomerate, many engines and products |
Please contact these companies directly in order to
find any more information.
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