Minimize lag when using System.Speech.Synthesis

Question

I am playing with using TTS built into .NET 4 and want the speech to happen immediately, but am instead encountering a lag between when I call Speak and when I get the audio.

I am developing a simple count-down timer that calls off the last five seconds and completion (5... 4... 3... 2... 1... Done), but when the screen updates with the new time, the TTS lags behind, getting worse for every invocation. I tried using SpeakAsync, but this only made it worse. Currently, Speak is being called outside the UI thread (in the Timer Tick event handler).

Is there a way to minimize this lag, such as pre-computing the speech and caching it or creating some kind of special TTS thread?

Answer 1

I somehow read past the API call I needed at least a hundred times. I was looking for SpeechSynthesizer.SetOutputToWaveStream.

MemoryStream stream = new MemoryStream();
SpeechSynthesizer synth = new SpeechSynthesizer();
synth.SetOutputToWaveStream(stream);
synth.Play(text);
stream.Position = 0;
SoundPlayer player = new SoundPlayer(stream);
player.Play();

This code will use TTS to turn text into a WAV file that is streamed into stream. You need to reset the position of the MemoryStream so that when you create a SoundPlayer from it, it starts reading the stream from the beginning instead of the end. Once you have the SoundPlayer initialized, you can save it somewhere so you can play it later instantly instead of having to wait for the TTS to initialize and play the sound.