Using Jacob in Java for Windows Speech Synthesis and Audio File Generation

Scenario: generate an audio file on a server from Chinese text by invoking Windows speech synthesis through the Jacob COM bridge.

First, download the Jacob DLL and JAR from the provided link, unzip the archive, and locate the required jacob.dll and jacob.jar files.

Copy the two DLL files into the Java runtime's bin directory, for example C:\Program Files\Java\jdk1.8.0_241\bin.

In Eclipse, create a new Java project, add a lib folder, and copy jacob.jar into it. Then create a package and a main class.

Configure the build path: right‑click the project → Build Path → Configure Build Path, then in the Libraries tab click Add JARs and select the JAR from the lib folder, apply and close.

Replace the generated main method with the following code, which creates COM objects for Sapi.SpVoice, sets volume and rate, speaks a string, then redirects the audio output to a file stream and saves a .wav file.

package com.badao.jacob;

import com.jacob.activeX.ActiveXComponent;
import com.jacob.com.Dispatch;
import com.jacob.com.Variant;

public class TTSMain {
    public static void main(String[] args) {
        ActiveXComponent ax = null;
        String str = "Sample text for speech synthesis";
        try {
            ax = new ActiveXComponent("Sapi.SpVoice");
            // Output speech content at runtime
            Dispatch spVoice = ax.getObject();
            // Volume 0-100
            ax.setProperty("Volume", new Variant(100));
            // Speech rate -10 to +10
            ax.setProperty("Rate", new Variant(-2));
            // Execute speech
            Dispatch.call(spVoice, "Speak", new Variant(str));

            // Below is building a file stream to generate an audio file
            ax = new ActiveXComponent("Sapi.SpFileStream");
            Dispatch spFileStream = ax.getObject();

            ax = new ActiveXComponent("Sapi.SpAudioFormat");
            Dispatch spAudioFormat = ax.getObject();

            // Set audio stream format
            Dispatch.put(spAudioFormat, "Type", new Variant(22));
            // Set file output stream format
            Dispatch.putRef(spFileStream, "Format", spAudioFormat);
            // Call output file stream open method to create a .wav file
            Dispatch.call(spFileStream, "Open", new Variant("D:\\badao.wav"), new Variant(3), new Variant(true));
            // Set the voice object's audio output stream to the output file object
            Dispatch.putRef(spVoice, "AudioOutputStream", spFileStream);
            // Set volume 0-100
            Dispatch.put(spVoice, "Volume", new Variant(100));
            // Set speech rate
            Dispatch.put(spVoice, "Rate", new Variant(-2));
            // Start speaking
            Dispatch.call(spVoice, "Speak", new Variant(str));

            // Close output file
            Dispatch.call(spFileStream, "Close");
            Dispatch.putRef(spVoice, "AudioOutputStream", null);

            spAudioFormat.safeRelease();
            spFileStream.safeRelease();
            spVoice.safeRelease();
            ax.safeRelease();
            System.out.println("Speech synthesis succeeded");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Specify the output path (e.g., D:\badao.wav) and ensure the directory exists. Right‑click the class in Eclipse and choose Run As → Java Application. If no errors appear and the console prints the success message, the WAV file will be created at the specified location.

Example code can be downloaded from the provided link.