How can I get the alternates of SAPI speech recognization result - sapi

Question

On windows7 platform I can use System.Speech.Recognition.SpeechRecognitionEngine to convert voice to text.By SpeechRecognitionEngine when the SpeechRecognized event triggered I can get some alternate words,and I can show these word to users for choise.
void engine_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
{
if (this.SpeechRecognized != null)
{
this.SpeechRecognized(this, new RecognizedResultEventArgs
{
Text = e.Result.Text,
Alternates = new ReadOnlyCollection<string>(e.Result.Alternates.Select(p => p.Text).ToList())
});
}
}
By the way,when I initialise SpeechRecognitionEngine instance,I want to load some specifical word instead of use "DictationGrammar".
My program need to runing on xp platform sometimes.So I want to implament a specific vertion to run on xp operating system by use sapi5.1.
I have readed a portion of sapi 5.1 document,then I get that:in sapi5.1,I can use "command and control" way to do that. but the "Result.Alternates()" method can not be used when I use "command and control".So,how can I achieve the same effect of SpeechRecognitionEngine ?
I tried the following code and there is an com Eception:
public void RecoContext_Recognition(int StreamNumber, object StreamPosition, SpeechRecognitionType RecognitionType, ISpeechRecoResult Result)
{
ISpeechPhraseProperty oItem;
oItem = Result.PhraseInfo.Properties.Item(0);
if ((System.Decimal)Result.PhraseInfo.GrammarId == grammarId)
{
if (this.SpeechRecognized != null)
{
RecognizedResultEventArgs e = new RecognizedResultEventArgs();
e.Text = oItem.Name;
// The following code throws an exception
ISpeechPhraseAlternates alternates = Result.Alternates(10);
List<string> s = new List<string>();
foreach (ISpeechPhraseAlternate item in alternates)
{
s.Add(item.RecoResult.PhraseInfo.Properties.Item(0).Name);
}
e.Alternates = new ReadOnlyCollection<string>(s);
this.SpeechRecognized(this, e);
}
}
}
Is there any way to get the alternates by use sapi by way of COM?Thank you.

Answer 1

In SAPI (any version), command and control grammars don't have alternates. Only dictation grammars have alternates.