Speech recognition using a real time stream

Question

Firstly, in order to clarify my goal: I am using the CSCore library and capturing background audio using the WasapiLoopbackCapture class, and I intend to use that as a real time input for a System.Speech.Recognition recognition engine. That class either outputs the data to a .WAV file or to a Stream. I then tried doing this:

    private void startButton_Click(object sender, EventArgs e)
    {
        _recognitionEngine.UnloadAllGrammars();
        _recognitionEngine.LoadGrammar(new DictationGrammar());

        LoadTargetDevice();
        StartStreamCapture(); // Here I am starting the capture to _stream (MemoryStream type)

        _stream.Position = 0; // Without setting this, I get a stream format exception.

        _recognitionEngine.SetInputToWaveStream(_stream);
        _recognitionEngine.RecognizeAsync(RecognizeMode.Multiple);
    }

The result is that I don't get an exception but I also don't get the SpeechRecognized or SpeechDetected events firing. I suspect this is because the System.Speech.Recognition assembly does not support real time streams. I searched online and someone reports implementing a custom Stream type as a workaround, but I was unable to follow the instructions on the post which were unclear (see Dexter Morgan's reply here).

I am aware this problem is best solved by using a different library or an alternate approach, but I would like to know how to do this makeshift implementation specifically, mostly for knowledge purposes.

Thanks!

Answer 1

@Justcarty thanks for the clarification, here is my Explanation why Code of OP wont work and what need to be done in order to make it work.

In C# for the speech recongintion and synthesis , you probably confused by the documentation where we are having two Speech DLL's
1. Microsoft Speech DLL (Microsoft.speech.dll) 2. System Speech DLL (System.Speech.Dll)

System.speech dll is a part of the windows OS . The two libraries are similar in the sense that the APIs are almost, but not quite, the same. So, if you’re searching online for speech examples , from the code snippets you get you may not tell whether they explaining to System.Speech or Microsoft.Speech.

So for Adding a Speech to the C# application you need to use the Microsoft.Speech library, not the System.Speech library.

Some of the key differences are summarized belows

|-------------------------|---------------------|
|  Microsoft.Speech.dll    | System.Speech.dll  |
|-------------------------|---------------------|
|Must install separately  |                     |
|                         | Part of the OS      |
|                         |  (Windows Vista+)   |
|-------------------------|---------------------|
|Must construct Grammars  | Uses Grammars or    |
|                           free dictation      |
| ------------------------|--------------------|

For more Read the Following Article , it explains the correct way to implement