The τ Project documentation.
The τ (tau) Project

pub version

The τ (tau) Project (or simply “τ”) is a set of libraries which deal with audio :

  • A player for audio playback
  • A recorder for recording audio
  • An Audio Graph engine
  • Several utilities to handle audio files

Supported targets

τ is a library package allowing you to play and record audio for

  • iOS
  • Android
  • Web

Later, τ will support also :

  • Linux
  • Macos
  • Windows


τ provides both a high level API and widgets for:

  • play audio
  • record audio

τ can be used to play a beep from an asset all the way up to implementing a complete media player.

The API is designed so you can use the supplied widgets or roll your own.

The τ package supports playback from:

  • Assets
  • Files
  • URL
  • Streams
  • Remote URI

SDK requirements

  • τ requires an iOS 10.0 SDK (or later)
  • τ requires an Android 21 (or later)

Examples (Demo Apps)

τ comes with several Demo/Examples :

The examples App is a driver which can call all the various examples.


The τ package includes the following features :

  • Play and Record τ or music with various codecs. (See the supported codecs here)
  • Play local or remote files specified by their URL.
  • Play assets.
  • Record to a live stream Stream
  • Playback from a live Stream
  • The App playback can be controlled from the device lock screen or from an Apple watch
  • Play audio using the built in [SoundPlayerUI] Widget.
  • Roll your own UI utilizing the τ api.
  • Record audio using the builtin [SoundRecorderUI] Widget.
  • Roll your own Recording UI utilizing the τ api.
  • Support for releasing/resuming resources when the app pauses/resumes.
  • Record to a Dart Stream
  • Playback from a Dart Stream
  • The App playback can be controlled from the device lock screen or from an Apple watch

Supported frameworks

τ is actually supported by the following frameworks:

  • Flutter (Flutter Sound)

τ will eventually be supported in the future by other frameworks :

  • React Native,
  • Cordova,
  • JS (React JS, Vue, Pure JS),


Flutter Sound 8.3 was published under the LGPL License. A Flutter Sound developer noticed recently that this license was incorrect : the LGPL license does not allow static links to the library. The library must be linked dynamically. The problem was that Flutter links-edit the plugins statically. This means that many Flutter Sound users who use our library in private/close sources App was in a copyright infringement.

To solve this issue, we forked Flutter Sound 8.3 to two different branches.

  • Flutter Sound 8.4 is published under the permissive Mozilla Public License 2.0.
  • The τ Sound Project 9.0 (this fork) is published under a pure GPL License.

τ Sound is copyrighted by Canardoux (2021).

  • τ Sound is released under a license with a strong copyleft clause: the GPL-V3 license. This means that if you use total or part of τ Sound, your App must be published under the GPL License too.
  • If you cannot (or don’t want to) publish your App under the GPL License, perhaps you can consider using the MPL Flutter Sound 8.4 branch.

We need help

τ is a fundamental building block needed by almost every mobile project.

We are looking to make τ the go to project for mobile Audio with support for various platforms and various OS.

τ is a large and complex project which requires to maintain multiple hardware platforms and test environments.


Too many projects to manage. I am burning out slowly. If you could help me cheer up, buy me a cup of coffee will make my life really happy and get much energy out of it. As a side effect, we will know that the τ Project is important for you, that you appreciate our job and that you can show it with a little money.


Tags: tau