System.Speech.Synthesis.TtsEngine Namespace
Supports the creation of Speech Synthesis Markup Language (SSML) based custom engines for rendering text to speech (TTS).
The members of the System.Speech.Synthesis.TtsEngine namespace make available Windows Desktop Speech Technology support for Speech Synthesis Markup Language (SSML) based markup language and the construction of synthetic speech engines.
The SSML markup language is the industry standard to provide a rich, XML-based language for assisting the synthetic speech engines. It is endorsed by Microsoft and our competitors. For more information on SSML, see Speech Synthesis Markup Language Specification.
Creating of a new of synthetic speech engine using System.Speech.Synthesis.TtsEngine requires the implementation and registration of an object derived from the abstract base class TtsEngineSsml.
System.Speech.Synthesis.TtsEngine based synthetic speech engines are accessed through Windows Desktop Speech Technology infrastructure, using the tools in the System.Speech.Synthesis namespace, in particular SpeechSynthesizer object, and are never directly used by applications.
The Windows Desktop Speech Technology infrastructures ensures that all parameters passed to a synthetic speech engine are validated and thread synchronized.
A of synthetic speech engine implemented using System.Speech.Synthesis.TtsEngine technology can:
Receive input, (see Speak,.TextFragment, FragmentState, and SkipInfo )
Queue events, and specify actions TtsEngineAction, ITtsEngineSite, EventParameterType, [T:System.Speech.Synthesis.TtsEngine.SpeechEventInfo).]
Control the control the pitch, speaking rate and volume of the speech output (see ContourPoint, ContourPointChangeType, EmphasisBreak, EmphasisWord, Prosody, ProsodyNumber, ProsodyPitch, ProsodyRange, ProsodyRate, ProsodyUnit, and ProsodyVolume)
Determine usage and output target of speech synthesis (see SayAs, SpeakOutputFormat)
| Class | Description | |
|---|---|---|
![]() | Prosody | Represents a collection of settings for voice properties such as Pitch, Rate and Volume. |
![]() | SayAs | |
![]() | SkipInfo | Provides information about text stream items to be skipped. |
![]() | TextFragment | Contains text and speech attribute information for consumption by a speech synthsizer engine. |
![]() | TtsEngineSsml | Abstract base class to be implemented by all text to speech synthesis engines. |
| Structure | Description | |
|---|---|---|
![]() | ContourPoint | Represents the volume for a text fragment with which the ContourPoint is associated. |
![]() | FragmentState | Provides detailed information about a TextFragment. |
![]() | ProsodyNumber | |
![]() | SpeechEventInfo | Used to specify the type of event, and its arguments (if any) to be generated as part of the rendering of text to speech by a custom synthetic speech engine. |
| Interface | Description | |
|---|---|---|
![]() | ITtsEngineSite | Provides methods for writing audio data and events. |
| Enumeration | Description | |
|---|---|---|
![]() | ContourPointChangeType | Enumerates values for the types of ContourPoint change. |
![]() | EmphasisBreak | Enumerates values for lengths of EmphasisBreak between spoken words. |
![]() | EmphasisWord | Enumerates the values of EmphasisWord for a specific TextFragment. |
![]() | EventParameterType | Enumerates the types of data pointers passed to speech synthesis events. |
![]() | ProsodyPitch | Enumerates values for the Pitch property of a Prosody object. |
![]() | ProsodyRange | Enumerates values for the Range property of a Prosody object. |
![]() | ProsodyRate | Enumerates values for the Rate property of a Prosody object. |
![]() | ProsodyUnit | Enumerates values for the Unit property on the Prosody object. |
![]() | ProsodyVolume | Enumerates values for the Volume property of a Prosody object. |
![]() | SpeakOutputFormat | Enumerates the types of speech output formats. |
![]() | TtsEngineAction | Specifies the Speech Synthesis Markup Language (SSML) action to be taken in rendering a given TextFragment. |
![]() | TtsEventId | Enumerates types of speech synthesis events. |



