TtsEngineSsml.Speak Method

Renders specified TextFragment array in the specified output format.

Namespace:  System.Speech.Synthesis.TtsEngine
Assembly:  System.Speech (in System.Speech.dll)

public abstract void Speak(
	TextFragment[] fragment,
	IntPtr waveHeader,
	ITtsEngineSite site
)

Parameters

fragment
Type: System.Speech.Synthesis.TtsEngine.TextFragment[]
An array of TextFragment instances containing the text to be rendered into speech.
waveHeader
Type: System.IntPtr
An IntPtr pointing to a structure containing audio output format.
site
Type: System.Speech.Synthesis.TtsEngine.ITtsEngineSite
A reference to an ITtsEngineSite interface passed in by the platform infrastructure to allow access to the infrastructure resources.

The structure used as waveHeader and returned by the method should compatible with the WAVEFORMATEX available under SAPI.

The struct must provide functionality equivalent to:

internal struct WaveFormat
{
    public Int16 FormatTag;
    public Int16 Channels;
    public int SamplesPerSec;
    public int AvgBytesPerSec;
    public Int16 BlockAlign;
    public Int16 BitsPerSample;
    public Int16 Size;
}

Notes to Inheritors

Custom speech synthesizer implements using TtsEngineSsml and Speak work as filters or intermediaries between synthesizer applications constructed using the platform infrastructure through the members of the System.Speech.Synthesis namespace and underlying system speech synthesis engines.

A Speak implementation:

  1. Traps or modify aspects of the incoming TextFragment objects

  2. Generates any necessary events using the site reference to a ITtsEngineSite instance

  3. Generates the actual synthesized speech.

Generation of speech is most typically done by calling Speak on one of the speech rendering engines provided by the operating system.

If one of the available speech rendering engines is not used, a object inheriting from TtsEngineSsml must create its own speech rendering engine.

Access to the Speak method on obtained using the registry and reflection. .

When you inherit from TtsEngineSsml, you must override the following members: TtsEngineSsml, AddLexicon, RemoveLexicon, [M:System.Speech.Synthesis.TtsEngine.TtsEngineSsml.GetOutputFormat(System.Speech.Synthesis.TtsEngine.SpeakOutputFormat,System.IntPtr),] and Speak.

The example below is part of a custom speech synthesis implementation inheriting from TtsEngineSsml, and using the use of TextFragment, SpeechEventInfo, FragmentState, and TtsEventID

The implementation of Speak()

  1. Receives an array of TextFragment instances and creates a new array of TextFragment instances to be passed to the Speak method on an underlying synthesis engine.

  2. If the TtsEngineAction enumeration value by found from the Action property on the FragmentState returned by the State property of each TextFragment instance is Speak, the implementation

    • Translates Americanism to Britishisms in the text to be spoken.

    • If the EventInterest property on the ITtsEngineSite interfaces provided to the implementation support the WordBoundary event type, a SpeechEventInfo instance is used to create an event to drive a synthesizer progress meter is created.

  3. A speech rendering engine is then called with the modified TextFragment array.

private const int WordBoundaryFlag = 1 << (int)TtsEventId.WordBoundary;
private readonly char[] spaces = new char[] { ' ', '\t', '\r', '\n' };
internal struct UsVsUk
{
  internal string UK;
  internal string US;
}

override public void Speak (TextFragment [] frags, IntPtr wfx, ITtsEngineSite site)
{
  TextFragment [] newFrags=new TextFragment[frags.Length];
  
  for (int i=0;i<frags.Length;i++){
    newFrags[i].State=frags[i].State;
    //truncate
    newFrags[i].TextToSpeak = frags[i].TextToSpeak.Substring(frags[i].TextOffset,
                               frags[i].TextLength);
    newFrags[i].TextLength = newFrags[i].TextToSpeak.Length;
    newFrags[i].TextOffset = 0;
    if (newFrags[i].State.Action == TtsEngineAction.Speak) {
      //Us to UK conversion
      foreach (UsVsUk term in TransList) {
      newFrags[i].TextToSpeak.Replace(term.US, term.UK);
      }
      //Generate progress meter events if supported
      if ((site.EventInterest & WordBoundaryFlag) != 0) {
      string[] subs = newFrags[i].TextToSpeak.Split(spaces);
        
      foreach (string s in subs) {
        int offset = newFrags[i].TextOffset;
        SpeechEventInfo spEvent = new SpeechEventInfo((Int16)TtsEventId.WordBoundary, 
                (Int16)EventParameterType.Undefined, 
                 s.Length, new IntPtr(offset));
        offset += s.Length;
        if (s.Trim().Length > 0) {
          SpeechEventInfo[] events = new SpeechEventInfo[1];
          events[0] = spEvent;
          site.AddEvents(events, 1);
        }
      }
      }
    }
  }
    _baseSynthesize.Speak(newFrags, wfx, site);
  
}

.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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