Lego NXT Pre- Defined Text to Speech
By Anna Sandler
This is an advanced topic, please make sure you've read the:
"What is a NXT Bluetooth Telegram",
"Lego NXT File Handling- Introduction",
"Create Files",
"Write To Files",
"Save and Close" and
"Play a Sound"
tutorials before you continue reading this chapter.
NXT doesn’t have a build in text to speech mechanism,
However, there is still some cool stuff that we can do with the pre-defined text to speech.
How does it work?
The following is a summary of the action steps (each step is described below):
- Use a text to speech software on your computer to create a WAV file;
- Convert the WAV file to the RSO- NXT sound file format;
- Alternatively, to the steps above, you can use the audio editor that is built in Mindstorm's official software.
It created RSO files from recording or a WAV file;
- Transfer the RSO file to NXT’s brick using the
FileOpenWriteCreate command ->
FileWrite command and
FileClose command or manually using Bluetooth file transfer;
- When the time comes, use the
PlaySoundFile command to make the robot “say” the pre-defined text;
Numeric speech
For pre- defined numeric speech all you need to do is to prepare the speech of:
- First 10 digits 0-9;
- The numbers: 10, 11, 12, 13, 15;
- The suffix “teen”;
- Twenty, thirty…
Now you have the combination for every number you want the robot to pronounce;
Preparations
Create a WAV file from text
- Open the Free Audio Editor software that you’ve installed in the Preparations section;
- Press the “Text to Speech” button as shown in this screenshot;
- Select 8000 in the Sample Rate drop-down list, Mono in “Channels” section and press OK;
Free Audio Editor Text to Speech Minimum Configuration
-
In the Synthesize Speech window that is opened, type the text that you want the robot to say for later use,
and press the Synthesize Speech button;
Free Audio Editor Text Synthesize Speech
- Save the file;
- In the Wave File Setup window that is opened, select the Specify Settings option and press the Configure button;
Free Audio Editor Wave File Setup
- In the Configure Wave Settings window that is opened,
select the 8000 Hz as Sample Rate, 8 bits as Bit Depth and Mono as Channels and press OK;
Free Audio Editor Configure Wave Settings
- Make sure that the wave file’s size does not exceed the 64k;
Convert the WAV file to RSO
- Open the wav2rso freeware that you’ve installed in the Preparations section;
- Click the Directory button, to select the working directory for the output of the converted RSO file;
- Click the Select button, to select your wave file you just made, ready for conversion;
- Select Linear from the list and set Rate to 8000;
- Select the Compress check box;
- Press the Convert button to finish;
wav2rso Converter
Transfer / download the RSO file to NXT’s brick programmatically
- Create an empty rso file on the NXT using
FileOpenWriteCreate command;
- In your code open the rso file for reading purposes;
- Read file bytes;
- Use the
FileWrite command to write every 61 bytes to the empty file that has just been created;
- Use the
FileClose command to save the changes in the file;
Make the robot say a predefined text
Use the
PlaySoundFile command to play the sound file;