Creating a ASP.NET application converting text to speech

Question

I seek some insight in creating an application that converts text to speech in ASP.NET. From my initial research, it appears that:

1. MS SAPI requires the client to download an ActiveX component and can support large amounts of text to be converted. Our clients are not willing to install any components on their systems, so this approach may or may not fly.

2. I do understand with .NET 3.0, we have the System.Speech.Synthesis namespace. Does the conversion take place on the server? If so, how would I serve it to the client?

Our requirements are ability to convert large amount of text, should be scalable and reliable. Which technology is "production ready" capable of serving a large number of requests in a short time interval.

Any thoughts are appreciated.

Answer 1

By default, ASP.Net applications don't run with sufficient permissions to access Speech Synthesis, and attempting to run Larsenal's code will fail with a security error.

I was able to get around this in an app by having a separate WCF service running on the server, as a regular Windows Service. The ASP.Net application then communicated with that service. That service just wrapped Larsenal's code, returning an array of bytes, given a string of text.

Also, one megabyte of text? That's a good-sized novel.

Edit, 11-12-09, answering some comments:

System.Speech can either return an array of bytes, or save to a wav file, which you can then feed to a media player embedded on the user's page. When I built my talking web page, it worked like this:

1) Page.aspx includes an 'embed' tag that puts a Windows Media Player on the page. The source is "PlayText.aspx?Textid=whatever".
2) PlayText.aspx loads the appropriate text, and communicates (via WCF) to the speechreader service, handing it the text to read.
3) The Speechreader service creates a MemoryStream and calls SpeechSynthesiser.SetOutputToWaveStream, and then returns the stream as a single array of bytes. This array is Response.Write()-ed to the client.

Here's the meat of the SpeechReader service:

    byte[] ITextReader.SpeakText(string text)
    {
        using (SpeechSynthesizer s = new SpeechSynthesizer())
        {
            using (MemoryStream ms = new MemoryStream())
            {
                s.SetOutputToWaveStream(ms);
                s.Speak(text);
                return ms.GetBuffer();
            }
        }
    }

I'm pretty sure that on the back end, this returns an enormous XML array-of-bytes, and is horribly inefficient. I just did it as a proof of concept, and so didn't research that. If you intend to use this in production, make sure that it's not internally returning something like this:

<byte>23</byte>
<byte>42</byte>
<byte>117</byte>
...

Answer 2

With the SpeechSynthesizer, you can output to a WAV file. You could then have a secondary process compress or convert to another format if needed. All this could be done on the server and then sent up through the browser.

This CodeProject article is a good introduction to .NET Speech Synthesis.

If you want to see how it performs with a LOT of text.... Add a reference to System.Speech and then use the following as a starting point:

using System;
using System.Speech.Synthesis;

namespace SpeakToMe
{
    class Program
    {
        static void Main(string[] args)
        {
            SpeechSynthesizer synth = new SpeechSynthesizer();
            synth.SetOutputToWaveFile("c:\\test.wav");
            synth.Speak("Hello, world.");
            synth.SetOutputToDefaultAudioDevice();

            Console.ReadLine();
        }
    }
}

A quick test on a file of 44,700 words (238KB) on my relatively fast machine...

• Completed in 55 seconds
• Generated a 626 MB WAV file

Answer 3

I searched for "Convert Text Into Speech In Asp.Net" in Google and found a very nice and usefull link:

http://codeprojectdownload.com/asp-net-2/convert-text-into-speech-in-asp-net/#.T0ScXIfXDZE

It may also be useful to you.

Answer 4

I achieved this by using codeBehind to run a javascript function that runs the text-to-speech command:

codeBehind:

Page.ClientScript.RegisterStartupScript(
GetType(), 
"anythingHere", 
"nameOfFunction();", 
true);

javascript:

<script>
  function nameOfFunction()
    {//start
       var msg = new SpeechSynthesisUtterance('READ ME!');
       window.speechSynthesis.speak(msg);
    }//end
</script>

Answer 5

I wrote an article on this on my blog: http://weblogs.asp.net/ricardoperes/archive/2014/04/08/speech-synthesis-with-asp-net-and-html5.aspx. I used AJAX and Data URIs to send voice data back and forth between the client and the server.