C# SAPI in a web service

var speechEngine = new SpVoiceClass();
SetVoice(speechEngine, job.Voice);

var fileMode = SpeechStreamFileMode.SSFMCreateForWrite;
var fileStream = new SpFileStream();
try
{
    fileStream.Open(filePath, fileMode, false);
    speechEngine.AudioOutputStream = fileStream;
    speechEngine.Speak(job.Script, SpeechVoiceSpeakFlags.SVSFPurgeBeforeSpeak | SpeechVoiceSpeakFlags.SVSFDefault); //TODO: Change to XML
    //Wait for 15 minutes only
    speechEngine.WaitUntilDone((uint)new TimeSpan(0, 15, 0).TotalMilliseconds);
}
finally
{
    fileStream.Close();
}

This exact code works in a WinForm app, but when I run it inside a webservice I get the following

System.Runtime.InteropServices.COMException was unhandled
  Message="Exception from HRESULT: 0x80045003"
  Source="Interop.SpeechLib"
  ErrorCode=-2147201021

Does anyone have any ideas what might be causing this error? The error code means

SPERR_UNSUPPORTED_FORMAT

For completeness here is the SetVoice method

void SetVoice(SpVoiceClass speechEngine, string voiceName)
{
    var voices = speechEngine.GetVoices(null, null);
    for (int index = 0; index < voices.Count; index++)
    {
        var currentToken = (SpObjectToken)voices.Item(index);
  开发者_如何学JAVA      if (currentToken.GetDescription(0) == voiceName)
        {
            speechEngine.SetVoice((ISpObjectToken)currentToken);
            return;
        }
    }
    throw new Exception("Voice not found: " + voiceName);
}

I have given full access to USERS on the folder C:\Temp where the file is to be written. Any help would be appreciated!

I don't think the System.Speech works in windows service. It looks like there is a dependency to Shell, which isn't available to services. Try interop with SAPI's C++ interfaces. Some class in System.Runtime.InteropServices may help on that.

Our naming convention requires us to use a non-standard file extension. This works fine in a Winforms app, but failed on our web server. Changing the file extension back to .wav solved this error for us.

Make sure you explicitly set the format on the SPFileStream object. ISpAudio::SetState (which gets called in a lower layer from speechEngine.Speak) will return SPERR_UNSUPPORTED_FORMAT if the format isn't supported.

I just got the webservice to spawn a console app to do the processing. PITA :-)