Building and using eSpeak NG on K1 to achieve speech-to-text conversion

eSpeak NG is a compact open source Text-to-Speech (TTS) synthesizer that supports multiple languages and accents and is suitable for Linux and other operating systems. Due to its small size and high performance, it is suitable for running on devices with limited resources, such as RISC-V development boards. This tutorial will guide you how to build and use eSpeak NG on a RISC-V development board.

Step 1: Prepare the environment

Before you start, please make sure your RISC-V development board is running Linux and the network is configured correctly.

Step 2: Install eSpeak NG

Since eSpeak NG supports running on Linux systems, you can install eSpeak NG on your RISC-V development board by following the steps below.

2.1 Update system packages

First, open the terminal and update the system package list:

sudo apt update

2.2 Installing Dependency Packages

Before installing eSpeak NG, make sure that all required dependencies are included in your system. You can install the required libraries and tools using the following command:

sudo apt install build-essential
sudo apt install libespeak-ng-dev

2.3 Clone the eSpeak NG repository and compile

Next, clone the eSpeak NG GitHub repository and start compiling:

git clone https://github.com/espeak-ng/espeak-ng.git
cd espeak-ng

Compile eSpeak NG:

./autogen.sh
./configure --prefix=/usr
make
sudo make install

Step 3: Text-to-speech using eSpeak NG

Once installed, you can convert text to speech using eSpeak NG. Here is a basic example that uses eSpeak NG to synthesize and output speech:

espeak-ng "Hello, this is a test on RISC-V development board."

This command will play the generated speech directly through the audio output device of the development board.

Step 4: Output the speech as a file

If you want to save the synthesized speech as a WAV file, you can use the -w parameter to specify the output file name. For example:

espeak-ng "This is a test of text-to-speech" -w output.wav

This will generate an output.wav file that you can play through any audio player.

Step 5: Customize voice

eSpeak NG supports multiple languages and accents. You can use the -v parameter to specify the voice. For example, to synthesize Chinese:

espeak-ng -v zh "你好，这是一个测试。"

Or use a different accent:

espeak-ng -v en-scottish "Hello, how are you?"

You can also adjust the speed and pitch of the speech. For example, to slow down the speech and raise the pitch:

espeak-ng -s 120 -p 80 "This is a slower and higher-pitched voice."

Step 6: Use SSML for speech synthesis

eSpeak NG supports the use of SSML (Speech Synthesis Markup Language) to precisely control speech output. Create a text file containing SSML, and then use eSpeak NG to synthesize speech:

<speak>
  <voice name="en">
    <prosody rate="slow" pitch="+10%">This is a test of SSML-based speech synthesis.</prosody>
  </voice>
</speak>

Use the following command to synthesize speech:

espeak-ng -m -f ssml_example.xml

Conclusion

Through this tutorial, you have successfully installed and used eSpeak NG for speech synthesis on the RISC-V development board. eSpeak NG provides powerful customization capabilities and can adapt to multiple languages and voice settings. By further studying the documentation of eSpeak NG, you can explore more advanced features, such as controlling speech output through SSML, generating speech files in different formats, etc.