Building a Flutter Speech to Text/Speech Recognizer Application

3년 전


What Will I Learn?

  • You will learn how to record sound with Flutter
  • You will learn how to setup an Android emulator to use the PC microphone
  • You will learn how to use the speech recognizer plugin for Flutter
  • You will learn how to interact with the Platform Messages from Android and iOS
  • You will learn how to override internationalization with this plugin


System Requirements:
OS Support for Flutter:
  • Windows 7 SP1 or later (64-bit)
  • macOS (64-bit)
  • Linux (64-bit)

Required Knowledge

  • A basic knowledge Programming
  • A fair understanding of Mobile development and Imperative or Object Oriented Programming
  • Basic knowledge of dependencies

Resources for Flutter and this Project:


Flutter Logo (Google):


  • Intermediate


In this Flutter Video Tutorial, we build a simple Text to Speech/Speech Recognizer application using the Speech Recognizer Flutter Plugin. The application takes in speech from a microphone on the Phone. It them passes that sound to the platform layer of the current phone. This sound is passed through an existing iOS or Android API and then translated to text. Its then passed back to the flutter layer of the application. We put this text into a box and display it to the user.

Sending and Receiving Platform Messages With Flutter

For the functionality of this application to work properly, the plugin needs to fully make use of Platform Messages and Channels. These Platform Messages provide us with a simple mechanism for communicating with platform specific APIs from iOS and Android. In this case, we are communicating with the speech recognition API that is a part of both platforms. For this to work properly, we need to define a bunch of callback functions for what our app should do in response to receiving and sending messages back and forth between the platforms.


The above flowchart gives us a decent idea of how the flow of the application works in this case. Speech comes in through the microphone of the phone or computer. This speech is digitized into bytes and passed back to the platform. The platform feeds it through the API which converts it into text. This text is then returned back to the flutter layer where it is injected into the Text Widget in our UI.

Setting Up the Features for our Application

While the plugin takes care of much of the Platform side logic and we also define a set of callbacks to respond to these Platform channels; we need to define the set of features that we want in our application. There are some obvious features like a Play/Record button and a Stop function and there are some less obvious ones like the Cancel Button. The user pushes the Play/Record button to start the record functionality and then they can either press Cancel or Stop to terminate it. Stop maintains the text in the widget while cancel clears the Text Widget.


Our three functionalities are tied to the three buttons in our application. The middle button activates the record functionality, the left button activates the cancel functionality and the right button stops recording. The small blue box at the bottom of the buttons is the Text widget and it fills up with the text that is sent back from the platform while the user is speaking.

The Source Code for this video may be found here:

Video Tutorial


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Proof of Work Done

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Hi @Tensor

Great to see another tutorial in the Flutter series.

I find this speech recognizer plugin for flutter a cool feature. The process of how this functions in terms of sending and receiving messages is very clear in your tutorial.

Thank you again for another great video tutorial contribution.

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Thank you @rosatravels, always a pleasure to read your comments.


Thank you for your review, @rosatravels! Keep up the good work!

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