C# SpeechSynthesizer makes service unresponsive

Question

I have the folowing code

[WebMethod]
public byte[] stringToWav(string text)
{
    SpeechSynthesizer ss = new SpeechSynthesizer();
    MemoryStream ms = new MemoryStream();
    ss.SetOutputToWaveStream(ms);
    ss.Speak(text);
    return ms.ToArray();
}

and the service returns nothing. Any idea why this happens?

Answer 1

I ran into the same exact problem with an ashx page.

I don't understand exactly why, but it seems that you need to use a separate thread and wait for it to complete.

The following code worked for me:

public byte[] TextToBytes(string textToSpeak)
{
    byte[] byteArr = null;

    var t = new System.Threading.Thread(() =>
    {
        SpeechSynthesizer ss = new SpeechSynthesizer();
        using (MemoryStream memoryStream = new MemoryStream())
        {
            ss.SetOutputToWaveStream(memoryStream);
            ss.Speak(textToSpeak);
            byteArr = memoryStream.ToArray();
        }
    });
    t.Start();
    t.Join();
    return byteArr;
}

Answer 2

Have you debugged and checked the value of ms.ToArray()? You might have better luck with ms.ToByteArray().