[C++/WinRT] How to use SpeechSynthesizer in UWP

Question

I would like to implement the text to speech feature in my app. I see there are docs on how to do this here: https://learn.microsoft.com/en-us/uwp/api/windows.media.speechsynthesis.speechsynthesizer .

However the example does not compile on a modern winrt app.

// The object for controlling the speech synthesis engine (voice).  
synth = ref new SpeechSynthesizer();  
// The media object for controlling and playing audio.  
media = ref new MediaElement();  
// The string to speak.  
String^ text = "Hello World";  
  
// Generate the audio stream from plain text.  
task speakTask = create_task(synth- >SynthesizeTextToStreamAsync(text));  
speakTask.then([this, text](SpeechSynthesisStream ^speechStream)  
{  
    // Send the stream to the media object.  
    // media === MediaElement XAML object.  
    media->SetSource(speechStream, speechStream->ContentType);  
    media->AutoPlay = true;  
    media->Play();  
});  

How can this example be adapted to work in a modern c++ winrt uwp app?

Answer 1

Hello,

Welcome to our Microsoft Q&A platform!

Since calling the SynthesizeTextToStreamAsync() method will start an asynchronous operation, in C++/Winrt you need to write a co_await statement to cooperatively await the result of any function that returns the asynchronous operation. Besides, if the asynchronous method does not communicate a result object or ongoing progress, you need to use IAsyncAction to be the return type. For more information about how to use asynchronous operation in C++/Winrt, you can refer to Concurrency and asynchronous operations with C++/WinRT.

The correct code will be the following:

.h  
private:  
	  Windows::Foundation::IAsyncAction playsound();  
  
.cpp  
Windows::Foundation::IAsyncAction MainPage::playsound() {  
		synth = Windows::Media::SpeechSynthesis::SpeechSynthesizer();  
  
		media = Windows::UI::Xaml::Controls::MediaElement();  
  
		// The string to speak.  
  
		hstring text = L"Hello World";  
  
		Windows::Media::SpeechSynthesis::SpeechSynthesisStream speechStream = co_await synth.SynthesizeTextToStreamAsync(text);  
  
		media.SetSource(speechStream, speechStream.ContentType());  
  
		media.AutoPlay(true);  
  
		media.Play();  
	}  
  

Besides, for more information about how to use the C++/Winrt in UWP, please check the following article:
https://learn.microsoft.com/en-us/windows/uwp/cpp-and-winrt-apis/.

Thanks