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

• A player for audio playback

• A recorder for recording audio

• Several utilities to handle audio files

Overview

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

• iOS

• Android

• Web

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

Features

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 platforms

τ is actually supported by the following frameworks:

• Flutter (Flutter Sound)

In the future, it will be (perhaps) supported by

• React Native (Tau React). (Not yet. Later).

• Cordova (Tau Cordova). (Not yet. Later).

• Others (Native Script, Solar 2D, ...)

Supported targets

τ is actually supported by the following OS :

• iOS

• Android

• Web

In the future, it will be (perhaps) supported by

• Linux

• others (Windows, MacOS)

What about Flutter Sound ?

We just changed the name of the project, because we want to encompass others frameworks than Flutter.

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.

nowPlaying()

• Dart API: nowPlaying().

This verb is used to set the Lock screen fields without starting a new playback. The fields 'dataBuffer' and 'trackPath' of the Track parameter are not used. Please refer to 'startPlayerFromTrack' for the meaning of the others parameters. Remark setUIProgressBar() is implemented only on iOS.

Example:

Dart

Javascript

    Track track = Track( codec: Codec.opusOGG, trackPath: fileUri, trackAuthor: '3 Inches of Blood', trackTitle: 'Axes of Evil', albumArtAsset: albumArt );
    await nowPlaying(Track);

        Lorem ipsum ...

</div>

Creating the Player instance.

• Dart API: constructor.

This is the first thing to do, if you want to deal with playbacks. The instanciation of a new player does not do many thing. You are safe if you put this instanciation inside a global or instance variable initialization.

Example:

Dart

Javascript

        FlutterSoundPlayer myPlayer = FlutterSoundPlayer();

        Lorem ipsum ...

</div>

How to use

First import the modules import 'flutter_sound.dart

The SoundPlayerUI provides a Playback widget styled after the HTML 5 audio player.

The player displays a loading indicator and allows the user to pause/resume/skip via the progress bar.

You can also pause/resume the player via an api call to SoundPlayerUI's state using a GlobalKey.

The SoundPlayerUI widget allows you to playback audio from multiple sources:

• File

• Asset

• URL

• Buffer

MediaFormat

When using the SoundPlayerUI you MUST pass a Track that has been initialised with a supported MediaFormat.

The Widget needs to obtain the duration of the audio that it is play and that can only be done if we know the MediaFormat of the Widget.

If you pass a Track that wasn't constructed with a MediaFormat then a MediaFormatException will be thrown.

The MediaFormat must also be natively supported by the OS. See mediaformat.md for additional details on checking for a supported format.

Example:

Track track;

/// global key so we can pause/resume the player via the api.
var playerStateKey = GlobalKey<SoundPlayerUIState>();

void initState()
{
   track = Track.fromAsset('assets/rock.mp3', mediaFormat: Mp3MediaFormat());
}

Widget build(BuildContext build)
{
    var player = SoundPlayerUI.fromTrack(track, key: playerStateKey);
    return
        Column(child: [
            player,
            RaisedButton("Pause", onPressed: () => playerState.currentState.pause()),
            RaisedButton("Resume", onPressed: () => playerState.currentState.resume())
        ]);
}

Sounds uses Track as the primary method of handing around audio data.

You can also dynamically load a Track when the user clicks the 'Play' button on the SoundPlayerUI widget. This allows you to delay the decision on what Track is going to be played until the user clicks the 'Play' button.

Track track;


void initState()
{
   track = Track.fromAsset('assets/rock.mp3', mediaFormat: Mp3MediaFormat());
}

Widget build(BuildContext build)
{
    return SoundPlayerUI.fromLoader((context) => loadTrack());
}

Future<Track> loadTrack()
{
    Track track;
    track = Track.fromAsset('assets/rock.mp3', mediaFormat: Mp3MediaFormat());

    track.title = "Asset playback.";
    track.artist = "By sounds";
}

τ is composed with 4 modules :

• FlutterSoundPlayer, wich deal with everything about playbacks

• FlutterSoundRecorder, which deal with everything about recording

• FlutterSoundHelper, which offers some convenients tools

• FlutterSoundUI, which offer some Widget ready to be used out of the box

To use Flutter Sound you just do :

import 'package:flutter_sound/flutter_sound.dart';

This will import all the necessaries dart interfaces.

Playback

1. Instance one ore more players. A good place to do that is in your init() function. It is also possible to instanciate the players "on the fly", when needed.

   Copy

   FlutterSoundPlayer myPlayer = FlutterSoundPlayer();

2. Open it. You cannot do anything on a close Player. An audio-session is then created.

   Copy

   myPlayer.openAudioSession().then( (){ ...} );

3. Use the various verbs implemented by the players.

4. startPlayer()

5. startPlayerFromStream()

6. startPlayerFromBuffer()

7. setVolume()

8. FlutterSoundPlayer.stopPlayer()

9. ...

10. Close your players.

    This is important to close every player open for freeing the resources taken by the audio session.

    A good place to do that is in the dispose() procedure.

    Copy

    myPlayer.closeAudioSession();

Recording

1. Instance your recorder. A good place to do that is in your init() function.

   Copy

   FlutterSoundRecorder myRecorder = FlutterSoundRecorder();

2. Open it. You cannot do anything on a close Recorder. An audio-session is then created.

   Copy

   myRecorder.openAudioSession().then( (){ ...} );

3. Use the various verbs implemented by the players.

4. startRecorder()

5. pauseRecorder()

6. resumeRecorder()

7. stopRecorder()

8. ...

9. Close your recorder.

   This is important to close it for freeing the resources taken by the audio session.

   A good place to do that is in the dispose() procedure.

   Copy

   myRecorder.closeAudioSession();

Demo

Demo

This is a Demo of what it is possible to do with Flutter Sound. The code of this Demo app is not so simple and unfortunately not very clean :-( .

Flutter Sound beginners : you probably should look to SimplePlayback and SimpleRecorder

The biggest interest of this Demo is that it shows most of the features of Flutter Sound :

• Plays from various media with various codecs

• Records to various media with various codecs

• Pause and Resume control from recording or playback

• Shows how to use a Stream for getting the playback (or recoding) events

• Shows how to specify a callback function when a playback is terminated,

• Shows how to record to a Stream or playback from a stream

• Can show controls on the iOS or Android lock-screen

• ...

It would be really great if someone rewrite this demo soon

The complete example source is there

• Flutter Sound user: your documentation is there

• The CHANGELOG file is here

Overview

Flutter Sound is a Flutter package allowing you to play and record audio for :

• Android

• iOS

• Flutter Web

Maybe, one day, we will be supported by Linux, Macos, and even (why not) Windows. But this is not top of our priorities.

Flutter Sound provides both a high level API and widgets for:

• play audio

• record audio

Flutter Sound 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.

Features

The Flutter Sound package includes the following features

• Play and Record flutter sound or music with various codecs.

• Play local or remote files specified by their URL.

• Play assets.

• Play audio using the built in SoundPlayerUI Widget.

• Roll your own UI utilising the Flutter Sound api.

• Record audio using the builtin SoundRecorderUI Widget.

• Roll your own Recording UI utilising the Flutter Sound 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 controled from the device lock screen or from an Apple watch

Changelog

You can find the changes here

Documentation

The documentation is here

License

Flutter Sound is copyrighted by Dooboolab (2018, 2019, 2020). Flutter Sound is released under a license with a copyleft clause: the LGPL-V3 license. This means that if you modify some of Flutter Sound code you must publish your modifications under the LGPL license too.

Help Maintenance

Flutter Sound is a fundamental building block needed by almost every flutter project.

I'm looking to make Flutter Sound the go to project for Flutter Audio with support for each of the Flutter supported platforms.

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

We greatly appreciate any contributions to the project which can be as simple as providing feedback on the API or documentation.

My friend Hyo has been maintaining quite many repos these days and he is burning out slowly. If you could help him cheer up, buy him a cup of coffee will make his life really happy and get much energy out of it. As a side effect, we will know that Flutter Sound is important for you, that you appreciate our job and that you can show it with a little money.

resumePlayer()

• Dart API: resumePlayer().

Use this verbe to resume the current playback. An exception is thrown if the player is not in the "paused" state.

Example:

Dart

Javascript

await myPlayer.resumePlayer();

        Lorem ipsum ...

</div>

pausePlayer()

• Dart API: .

Use this verbe to pause the current playback. An exception is thrown if the player is not in the "playing" state.

Example:

</div>

startPlayerFromTrack()

• Dart API: startPlayerFromTrack().

Use this verb to play data from a track specification and display controls on the lock screen or an Apple Watch. The Audio Session must have been open with the parameter withUI.

• track parameter is a simple structure which describe the sound to play. Please see here the Track structure specification

• whenFinished:() : A function for specifying what to do when the playback will be finished.

• onPaused:() : this parameter can be :

  • a call back function to call when the user hit the Skip Pause button on the lock screen

  • null : The pause button will be handled by Flutter Sound internal

• onSkipForward:() : this parameter can be :

  • a call back function to call when the user hit the Skip Forward button on the lock screen

  • null : The Skip Forward button will be disabled

• onSkipBackward:() : this parameter can be :

  • a call back function to call when the user hit the Skip Backward button on the lock screen

  • : The Skip Backward button will be disabled

• removeUIWhenStopped : is a boolean to specify if the UI on the lock screen must be removed when the sound is finished or when the App does a stopPlayer(). Most of the time this parameter must be true. It is used only for the rare cases where the App wants to control the lock screen between two playbacks. Be aware that if the UI is not removed, the button Pause/Resume, Skip Backward and Skip Forward remain active between two playbacks. If you want to disable those button, use the API verb nowPlaying(). Remark: actually this parameter is implemented only on iOS.

• defaultPauseResume : is a boolean value to specify if Flutter Sound must pause/resume the playback by itself when the user hit the pause/resume button. Set this parameter to FALSE if the App wants to manage itself the pause/resume button. If you do not specify this parameter and the onPaused parameter is specified then Flutter Sound will assume FALSE. If you do not specify this parameter and the onPaused parameter is not specified then Flutter Sound will assume TRUE. Remark: actually this parameter is implemented only on iOS.

startPlayerFromTrack() returns a Duration Future, which is the record duration.

Example:

Dart

Javascript

    final fileUri = "https://file-examples.com/wp-content/uploads/2017/11/file_example_MP3_700KB.mp3";
    Track track = Track( codec: Codec.opusOGG, trackPath: fileUri, trackAuthor: '3 Inches of Blood', trackTitle: 'Axes of Evil', albumArtAsset: albumArt )
    Duration d = await myPlayer.startPlayerFromTrack
    (
                track,
                whenFinished: ()
                {
                         print( 'I hope you enjoyed listening to this song' );
                },
    );

        Lorem ipsum ...

</div>

onProgress

• Dart API: .

The stream side of the Food Controller : this is a stream on which FlutterSound will post the player progression. You may listen to this Stream to have feedback on the current playback.

PlaybackDisposition has two fields :

• Duration duration (the total playback duration)

• Duration position (the current playback position)

Example:

</div>

playerState, isPlaying, isPaused, isStopped. getPlayerState()

• Dart API: getPlayerState().

• Dart API: isPlaying.

• Dart API: isPaused.

• Dart API: isStopped.

• Dart API: playerState.

This four verbs is used when the app wants to get the current Audio State of the player.

playerState is an attribut which can have the following values :

• isStopped /// Player is stopped

• isPlaying /// Player is playing

• isPaused /// Player is paused

• isPlaying is a boolean attribut which is true when the player is in the "Playing" mode.

• isPaused is a boolean atrribut which is true when the player is in the "Paused" mode.

• isStopped is a boolean atrribut which is true when the player is in the "Stopped" mode.

Flutter Sound shows in the playerState attribut the last known state. When the Audio State of the background OS engine changes, the playerState parameter is not updated exactly at the same time. If you want the exact background OS engine state you must use PlayerState theState = await myPlayer.getPlayerState(). Acutually getPlayerState() is only implemented on iOS.

Example:

Dart

Javascript

        swtich(myPlayer.playerState)
        {
                case PlayerState.isPlaying: doSomething; break;
                case PlayerState.isStopped: doSomething; break;
                case PlayerState.isPaused: doSomething; break;
        }
        ...
        if (myPlayer.isStopped) doSomething;
        if (myPlayer.isPlaying) doSomething;
        if (myPlayer.isPaused) doSomething;
        ...
        PlayerState theState = await myPlayer.getPlayerState();
        ...

        Lorem ipsum ...

</div>

Food

• Dart API: food.

• Dart API: foodData.

• Dart API: food.

This are the objects that you can add to foodSink The Food class has two others inherited classes :

• FoodData (the buffers that you want to play)

• FoodEvent (a call back to be called after a resynchronisation)

Example:

This example shows how to play Live data, without Back Pressure from Flutter Sound

Dart

Javascript

await myPlayer.startPlayerFromStream(codec: Codec.pcm16, numChannels: 1, sampleRate: 48000);

myPlayer.foodSink.add(FoodData(aBuffer));
myPlayer.foodSink.add(FoodData(anotherBuffer));
myPlayer.foodSink.add(FoodData(myOtherBuffer));
myPlayer.foodSink.add(FoodEvent(()async {await _mPlayer.stopPlayer(); setState((){});}));

        Lorem ipsum ...

</div>

foodSink

• Dart API: .

The sink side of the Food Controller that you use when you want to play asynchronously live data. This StreamSink accept two kinds of objects :

• FoodData (the buffers that you want to play)

• FoodEvent (a call back to be called after a resynchronisation)

Example:

shows how to play Live data, without Back Pressure from Flutter Sound

</div>

startPlayer()

• Dart API: .

You can use startPlayer to play a sound.

• startPlayer() has three optional parameters, depending on your sound source :

  • fromUri: (if you want to play a file or a remote URI)

  • fromDataBuffer: (if you want to play from a data buffer)

  • sampleRate is mandatory if codec == Codec.pcm16. Not used for other codecs.

You must specify one or the three parameters : fromUri, fromDataBuffer, fromStream.

• You use the optional parametercodec: for specifying the audio and file format of the file. Please refer to the to know which codecs are currently supported.

• whenFinished:() : A lambda function for specifying what to do when the playback will be finished.

Very often, the codec: parameter is not useful. Flutter Sound will adapt itself depending on the real format of the file provided. But this parameter is necessary when Flutter Sound must do format conversion (for example to play opusOGG on iOS).

startPlayer() returns a Duration Future, which is the record duration.

Hint: can be useful if you want to get access to some directories on your device.

Example:

</div>

Example:

</div>

isDecoderSupported()

• Dart API: .

This verb is useful to know if a particular codec is supported on the current platform. Returns a Future.

Example:

</div>

setAudioFocus()

• Dart API: .

focus: parameter possible values are

• AudioFocus.requestFocus (request focus, but do not do anything special with others App)

• AudioFocus.requestFocusAndStopOthers (your app will have exclusive use of the output audio)

• AudioFocus.requestFocusAndDuckOthers (if another App like Spotify use the output audio, its volume will be lowered)

• AudioFocus.requestFocusAndKeepOthers (your App will play sound above others App)

• AudioFocus.requestFocusAndInterruptSpokenAudioAndMixWithOthers

• AudioFocus.requestFocusTransient (for Android)

• AudioFocus.requestFocusTransientExclusive (for Android)

• AudioFocus.abandonFocus (Your App will not have anymore the audio focus)

Other parameters :

Please look to to understand the meaning of the other parameters

Example:

</div>

openAudioSession() and closeAudioSession()

• Dart API: openAudioSession.

• Dart API: closeAudioSession.

A player must be opened before used. A player correspond to an Audio Session. With other words, you must open the Audio Session before using it. When you have finished with a Player, you must close it. With other words, you must close your Audio Session. Opening a player takes resources inside the OS. Those resources are freed with the verb closeAudioSession(). It is safe to call this procedure at any time.

• If the Player is not open, this verb will do nothing

• If the Player is currently in play or pause mode, it will be stopped before.

focus: parameter

focus is an optional parameter can be specified during the opening : the Audio Focus. This parameter can have the following values :

• AudioFocus.requestFocusAndStopOthers (your app will have exclusive use of the output audio)

• AudioFocus.requestFocusAndDuckOthers (if another App like Spotify use the output audio, its volume will be lowered)

• AudioFocus.requestFocusAndKeepOthers (your App will play sound above others App)

• AudioFocus.requestFocusAndInterruptSpokenAudioAndMixWithOthers (for Android)

• AudioFocus.requestFocusTransient (for Android)

• AudioFocus.requestFocusTransientExclusive (for Android)

• AudioFocus.doNotRequestFocus (useful if you want to mangage yourself the Audio Focus with the verb setAudioFocus())

The Audio Focus is abandoned when you close your player. If your App must play several sounds, you will probably open your player just once, and close it when you have finished with the last sound. If you close and reopen an Audio Session for each sound, you will probably get unpleasant things for the ears with the Audio Focus.

category

category is an optional parameter used only on iOS. This parameter can have the following values :

• ambient

• multiRoute

• playAndRecord

• playback

• record

• soloAmbient

• audioProcessing

See iOS documentation to understand the meaning of this parameter.

mode

mode is an optional parameter used only on iOS. This parameter can have the following values :

• modeDefault

• modeGameChat

• modeMeasurement

• modeMoviePlayback

• modeSpokenAudio

• modeVideoChat

• modeVideoRecording

• modeVoiceChat

• modeVoicePrompt

See iOS documentation to understand the meaning of this parameter.

audioFlags

are a set of optional flags (used on iOS):

• outputToSpeaker

• allowHeadset

• allowEarPiece

• allowBlueTooth

• allowAirPlay

• allowBlueToothA2DP

device

is the output device (used on Android)

• speaker

• headset,

• earPiece,

• blueTooth,

• blueToothA2DP,

• airPlay

withUI

is a boolean that you set to true if you want to control your App from the lock-screen (using startPlayerFromTrack() during your Audio Session).

You MUST ensure that the player has been closed when your widget is detached from the UI. Overload your widget's dispose() method to closeAudioSession the player when your widget is disposed. In this way you will reset the player and clean up the device resources, but the player will be no longer usable.

@override
void dispose()
{
        if (myPlayer != null)
        {
            myPlayer.closeAudioSession();
            myPlayer = null;
        }
        super.dispose();
}

You may not open many Audio Sessions without closing them. You will be very bad if you try something like :

    while (aCondition)  // *DON'T DO THAT*
    {
            flutterSound = FlutterSoundPlayer().openAudioSession(); // A **new** Flutter Sound instance is created and opened
            flutterSound.startPlayer(bipSound);
    }

openAudioSession() and closeAudioSession() return Futures. You may not use your Player before the end of the initialization. So probably you will await the result of openAudioSession(). This result is the Player itself, so that you can collapse instanciation and initialization together with myPlayer = await FlutterSoundPlayer().openAudioSession();

Example:

Dart

Javascript

    myPlayer = await FlutterSoundPlayer().openAudioSession(focus: Focus.requestFocusAndDuckOthers, outputToSpeaker | allowBlueTooth);

    ...
    (do something with myPlayer)
    ...

    await myPlayer.closeAudioSession();
    myPlayer = null;
    FlutterSoundPlayer myPlayer = FlutterSoundPlayer();

        Lorem ipsum ...

</div>

getProgress()

• Dart API: getProgress().

This verb is used to get the current progress of a playback. It returns a Map with two Duration entries : 'progress' and 'duration'. Remark : actually only implemented on iOS.

Example:

Dart

Javascript

        Duration progress = (await getProgress())['progress'];
        Duration duration = (await getProgress())['duration'];

        Lorem ipsum ...

</div>

seekToPlayer()

• Dart API: seekToPlayer().

To seek to a new location. The player must already be playing or paused. If not, an exception is thrown.

Example:

Dart

Javascript

await myPlayer.seekToPlayer(Duration(milliseconds: milliSecs));

        Lorem ipsum ...

</div>

setUIProgressBar()

• Dart API: setUIProgressBar().

This verb is used if the App wants to control itself the Progress Bar on the lock screen. By default, this progress bar is handled automaticaly by Flutter Sound. Remark setUIProgressBar() is implemented only on iOS.

Example:

Dart

Javascript

        Duration progress = (await getProgress())['progress'];
        Duration duration = (await getProgress())['duration'];
        setUIProgressBar(progress: Duration(milliseconds: progress.milliseconds - 500), duration: duration)

        Lorem ipsum ...

</div>

feedFromStream()

• Dart API: feedFromStream().

This is the verb that you use when you want to play live PCM data synchronously. This procedure returns a Future. It is very important that you wait that this Future is completed before trying to play another buffer.

Example:

• This example shows how to play Live data, with Back Pressure from Flutter Sound

• This example shows how to play some real time sound effects synchronously.

Dart

Javascript

await myPlayer.startPlayerFromStream(codec: Codec.pcm16, numChannels: 1, sampleRate: 48000);

await myPlayer.feedFromStream(aBuffer);
await myPlayer.feedFromStream(anotherBuffer);
await myPlayer.feedFromStream(myOtherBuffer);

await myPlayer.stopPlayer();

        Lorem ipsum ...

</div>

stopPlayer()

• Dart API: .

Use this verb to stop a playback. This verb never throw any exception. It is safe to call it everywhere, for example when the App is not sure of the current Audio State and want to recover a clean reset state.

Example:

</div>

startPlayerFromStream()

• Dart API: .

This functionnality needs, at least, and Android SDK >= 21

• The only codec supported is actually Codec.pcm16.

• The only value possible for numChannels is actually 1.

• SampleRate is the sample rate of the data you want to play.

Please look to

Example You can look to the three provided examples :

• shows how to play Live data, with Back Pressure from Flutter Sound

• shows how to play Live data, without Back Pressure from Flutter Sound

• shows how to play some real time sound effects.

Example 1:

</div>

Example 2:

</div>

recorderState, isRecording, isPaused, isStopped

• Dart API:

• Dart API:

• Dart API:

• Dart API:

This four attributs is used when the app wants to get the current Audio State of the recorder.

recorderState is an attribut which can have the following values :

• isStopped /// Recorder is stopped

• isRecording /// Recorder is recording

• isPaused /// Recorder is paused

• isRecording is a boolean attribut which is true when the recorder is in the "Recording" mode.

• isPaused is a boolean atrribut which is true when the recorder is in the "Paused" mode.

• isStopped is a boolean atrribut which is true when the recorder is in the "Stopped" mode.

Example:

</div>

setSubscriptionDuration()

• Dart API: .

This verb is used to change the default interval between two post on the "Update Progress" stream. (The default interval is 0 (zero) which means "NO post")

Example:

</div>

setVolume()

• Dart API: .

The parameter is a floating point number between 0 and 1. Volume can be changed when player is running. Manage this after player starts.

Example:

</div>

resumeRecorder()

• Dart API:

On Android this API verb needs al least SDK-24. An exception is thrown if the Recorder is not currently paused.

Example:

</div>

setSubscriptionDuration()

• Dart API:

This verb is used to change the default interval between two post on the "Update Progress" stream. (The default interval is 0 (zero) which means "NO post")

Example:

</div>

pauseRecorder()

• Dart API:

On Android this API verb needs al least SDK-24. An exception is thrown if the Recorder is not currently recording.

Example:

</div>

Module instanciation

• Dart API: constructor

You do not need to instanciate the Flutter Sound Helper module. To use this module, you can just use the singleton offers by the module : flutterSoundHelper.

Example:

Dart

Javascript

        Duration t = await flutterSoundHelper.duration(aPathFile);

        Lorem ipsum ...

</div>

stopRecorder()

• Dart API: stopRecorder

Use this verb to stop a record. This verb never throws any exception. It is safe to call it everywhere, for example when the App is not sure of the current Audio State and want to recover a clean reset state.

Example:

Dart

Javascript

        await myRecorder.stopRecorder();
        if (_recorderSubscription != null)
        {
                _recorderSubscription.cancel();
                _recorderSubscription = null;
        }

        Lorem ipsum ...

</div>

-

setAudioFocus()

• Dart API: setAudioFocus

focus: parameter possible values are

• AudioFocus.requestFocus (request focus, but do not do anything special with others App)

• AudioFocus.requestFocusAndStopOthers (your app will have exclusive use of the output audio)

• AudioFocus.requestFocusAndDuckOthers (if another App like Spotify use the output audio, its volume will be lowered)

• AudioFocus.requestFocusAndKeepOthers (your App will play sound above others App)

• AudioFocus.requestFocusAndInterruptSpokenAudioAndMixWithOthers

• AudioFocus.requestFocusTransient (for Android)

• AudioFocus.requestFocusTransientExclusive (for Android)

• AudioFocus.abandonFocus (Your App will not have anymore the audio focus)

Other parameters :

Please look to openAudioSession() to understand the meaning of the other parameters

Example:

Dart

Javascript

        myPlayer.setAudioFocus(focus: AudioFocus.requestFocusAndDuckOthers);

        Lorem ipsum ...

</div>

onProgress

• Dart API: onProgress

The attribut onProgress is a stream on which FlutterSound will post the recorder progression. You may listen to this Stream to have feedback on the current recording.

Example:

Dart

Javascript

        _recorderSubscription = myrecorder.onProgress.listen((e)
        {
                Duration maxDuration = e.duration;
                double decibels = e.decibels
                ...
        }

        Lorem ipsum ...

</div>

startRecorder()

• Dart API: startRecorder

You use startRecorder() to start recording in an open session. startRecorder() has the destination file path as parameter. It has also 7 optional parameters to specify :

• codec: The codec to be used. Please refer to the Codec compatibility Table to know which codecs are currently supported.

• toFile: a path to the file being recorded

• toStream: if you want to record to a Dart Stream. Please look to the following notice. This new functionnality needs, at least, Android SDK >= 21 (23 is better)

• sampleRate: The sample rate in Hertz

• numChannels: The number of channels (1=monophony, 2=stereophony)

• bitRate: The bit rate in Hertz

• audioSource : possible value is :

  • defaultSource

  • microphone

  • voiceDownlink (if someone can explain me what it is, I will be grateful ;-) )

path_provider can be useful if you want to get access to some directories on your device.

Flutter Sound does not take care of the recording permission. It is the App responsability to check or require the Recording permission. Permission_handler is probably useful to do that.

Example:

Dart

Javascript

    // Request Microphone permission if needed
    PermissionStatus status = await Permission.microphone.request();
    if (status != PermissionStatus.granted)
            throw RecordingPermissionException("Microphone permission not granted");

    Directory tempDir = await getTemporaryDirectory();
    File outputFile = await File ('${tempDir.path}/flutter_sound-tmp.aac');
    await myRecorder.startRecorder(toFile: outputFile.path, codec: t_CODEC.CODEC_AAC,);

        Lorem ipsum ...

</div>

openAudioSession() and closeAudioSession()

• Dart API: openAudioSession

• Dart API: closeAudioSession

A recorder must be opened before used. A recorder correspond to an Audio Session. With other words, you must open the Audio Session before using it. When you have finished with a Recorder, you must close it. With other words, you must close your Audio Session. Opening a recorder takes resources inside the OS. Those resources are freed with the verb closeAudioSession().

You MUST ensure that the recorder has been closed when your widget is detached from the UI. Overload your widget's dispose() method to close the recorder when your widget is disposed. In this way you will reset the player and clean up the device resources, but the recorder will be no longer usable.

@override
void dispose()
{
        if (myRecorder != null)
        {
            myRecorder.closeAudioSession();
            myPlayer = null;
        }
        super.dispose();
}

You maynot openAudioSession many recorders without releasing them. You will be very bad if you try something like :

    while (aCondition)  // *DO'NT DO THAT*
    {
            flutterSound = FlutterSoundRecorder().openAudioSession(); // A **new** Flutter Sound instance is created and opened
            ...
    }

openAudioSession() and closeAudioSession() return Futures. You may not use your Recorder before the end of the initialization. So probably you will await the result of openAudioSession(). This result is the Recorder itself, so that you can collapse instanciation and initialization together with myRecorder = await FlutterSoundPlayer().openAudioSession();

The four optional parameters are used if you want to control the Audio Focus. Please look to FlutterSoundPlayer openAudioSession() to understand the meaning of those parameters

Example:

Dart

Javascript

    myRecorder = await FlutterSoundRecorder().openAudioSession();

    ...
    (do something with myRecorder)
    ...

    myRecorder.closeAudioSession();
    myRecorder = null;

        Lorem ipsum ...

</div>

isEncoderSupported()

• Dart API: isEncoderSupported

This verb is useful to know if a particular codec is supported on the current platform; Return a Future.

Example:

Dart

Javascript

       if ( await myRecorder.isEncoderSupported(Codec.opusOGG) ) doSomething;

        Lorem ipsum ...

</div>

pcmToWave()

• Dart API: pcmToWave()

This verb is usefull to convert a Raw PCM file to a Wave file.

It adds a Wave envelop to the PCM file, so that the file can be played back with startPlayer().

Note: the parameters numChannels and sampleRate are mandatory, and must match the actual PCM data. See here a discussion about Raw PCM and WAVE file format.

Example:

Dart

Javascript

        String inputFile = '$myInputPath/bar.pcm';
        var tempDir = await getTemporaryDirectory();
        String outpufFile = '${tempDir.path}/$foo.wav';
        await flutterSoundHelper.pcmToWave(inputFile: inputFile, outpoutFile: outputFile, numChannels: 1, sampleRate: 8000);

        Lorem ipsum ...

</div>

duration()

• Dart API: duration()

This verb is used to get an estimation of the duration of a sound file. Be aware that it is just an estimation, based on the Codec used and the sample rate.

Note : this verb uses FFmpeg and is not available int the LITE flavor of Flutter Sound.

Example:

Dart

Javascript

        Duration d = flutterSoundHelper.duration("$myFilePath/bar.wav");

        Lorem ipsum ...

</div>

waveToPCM()

• Dart API: waveToPCM()

This verb is usefull to convert a Wave file to a Raw PCM file.

It removes the Wave envelop from the PCM file.

Example:

Dart

Javascript

        String inputFile = '$myInputPath/bar.pcm';
        var tempDir = await getTemporaryDirectory();
        String outpufFile = '${tempDir.path}/$foo.wav';
        await flutterSoundHelper.waveToPCM(inputFile: inputFile, outpoutFile: outputFile);

        Lorem ipsum ...

</div>

isFFmpegAvailable()

• Dart API: isFFmpegAvailable()

This verb is used to know during runtime if FFmpeg is linked with the App.

Example:

Dart

Javascript

        if ( await flutterSoundHelper.isFFmpegAvailable() )
        {
                Duration d = flutterSoundHelper.duration("$myFilePath/bar.wav");
        }

        Lorem ipsum ...

</div>

getLastFFmpegReturnCode()

• Dart API: getLastFFmpegReturnCode()

This simple verb is used to get the result of the last FFmpeg command

Example:

Dart

Javascript

        int result = await getLastFFmpegReturnCode();

        Lorem ipsum ...

</div>

getLastFFmpegCommandOutput()

• Dart API:

This simple verb is used to get the output of the last FFmpeg command

Example:

</div>

ffMpegGetMediaInformation()

• Dart API:

This verb is used to get various informations on a file.

The informations got with FFmpegGetMediaInformation() are .

Example:

</div>

executeFFmpegWithArguments()

• Dart API:

This verb is a wrapper for the great FFmpeg application. The command "man ffmpeg" (if you have installed ffmpeg on your computer) will give you many informations. If you do not have ffmpeg on your computer you will find easyly on internet many documentation on this great program.

Example:

</div>

waveToPCMBuffer()

• Dart API:

This verb is usefull to convert a Wave buffer to a Raw PCM buffer. Note that this verb is not asynchronous and does not return a Future.

It removes the Wave envelop from the PCM buffer.

Example:

</div>

pcmToWaveBuffer()

• Dart API: pcmToWaveBuffer()

This verb is usefull to convert a Raw PCM buffer to a Wave buffer.

It adds a Wave envelop in front of the PCM buffer, so that the file can be played back with startPlayerFromBuffer().

Note: the parameters numChannels and sampleRate are mandatory, and must match the actual PCM data. See here a discussion about Raw PCM and WAVE file format.

Example:

Dart

Javascript

        Uint8List myWavBuffer = await flutterSoundHelper.pcmToWaveBuffer(inputBuffer: myPCMBuffer, numChannels: 1, sampleRate: 8000);

        Lorem ipsum ...

</div>

How to use

First import the modules import 'flutter_sound.dart

The SoundPlayerUI provides a Playback widget styled after the HTML 5 audio player.

The player displays a loading indicator and allows the user to pause/resume/skip via the progress bar.

You can also pause/resume the player via an api call to SoundPlayerUI's state using a GlobalKey.

The SoundPlayerUI widget allows you to playback audio from multiple sources:

• File

• Asset

• URL

• Buffer

MediaFormat

When using the SoundPlayerUI you MUST pass a Track that has been initialised with a supported MediaFormat.

The Widget needs to obtain the duration of the audio that it is play and that can only be done if we know the MediaFormat of the Widget.

If you pass a Track that wasn't constructed with a MediaFormat then a MediaFormatException will be thrown.

The MediaFormat must also be natively supported by the OS. See mediaformat.md for additional details on checking for a supported format.

Example:

Track track;

/// global key so we can pause/resume the player via the api.
var playerStateKey = GlobalKey<SoundPlayerUIState>();

void initState()
{
   track = Track.fromAsset('assets/rock.mp3', mediaFormat: Mp3MediaFormat());
}

Widget build(BuildContext build)
{
    var player = SoundPlayerUI.fromTrack(track, key: playerStateKey);
    return
        Column(child: [
            player,
            RaisedButton("Pause", onPressed: () => playerState.currentState.pause()),
            RaisedButton("Resume", onPressed: () => playerState.currentState.resume())
        ]);
}

Sounds uses Track as the primary method of handing around audio data.

You can also dynamically load a Track when the user clicks the 'Play' button on the SoundPlayerUI widget. This allows you to delay the decision on what Track is going to be played until the user clicks the 'Play' button.

Track track;


void initState()
{
   track = Track.fromAsset('assets/rock.mp3', mediaFormat: Mp3MediaFormat());
}

Widget build(BuildContext build)
{
    return SoundPlayerUI.fromLoader((context) => loadTrack());
}

Future<Track> loadTrack()
{
    Track track;
    track = Track.fromAsset('assets/rock.mp3', mediaFormat: Mp3MediaFormat());

    track.title = "Asset playback.";
    track.artist = "By sounds";
}

How to use

First import the modules import 'flutter_sound.dart

The SoundPlayerUI provides a Playback widget styled after the HTML 5 audio player.

The player displays a loading indicator and allows the user to pause/resume/skip via the progress bar.

You can also pause/resume the player via an api call to SoundPlayerUI's state using a GlobalKey.

The SoundPlayerUI widget allows you to playback audio from multiple sources:

• File

• Asset

• URL

• Buffer

MediaFormat

When using the SoundPlayerUI you MUST pass a Track that has been initialised with a supported MediaFormat.

The Widget needs to obtain the duration of the audio that it is play and that can only be done if we know the MediaFormat of the Widget.

If you pass a Track that wasn't constructed with a MediaFormat then a MediaFormatException will be thrown.

The MediaFormat must also be natively supported by the OS. See mediaformat.md for additional details on checking for a supported format.

Example:

Sounds uses as the primary method of handing around audio data.

You can also dynamically load a Track when the user clicks the 'Play' button on the SoundPlayerUI widget. This allows you to delay the decision on what Track is going to be played until the user clicks the 'Play' button.

• cc license

Module instanciation

Dart definition (prototype) :

FlutterSoundHelper flutterSoundHelper = FlutterSoundHelper(); // Singleton

You do not need to instanciate the Flutter Sound Helper module. To use this module, you can just use the singleton offers by the module : flutterSoundHelper.

Example:

Duration t = await flutterSoundHelper.duration(aPathFile);

convertFile()

Dart definition (prototype) :

Future<bool> convertFile
(
        String infile,
        Codec codecin,
        String outfile,
        Codec codecout
) async

This verb is useful to convert a sound file to a new format.

• infile is the file path of the file you want to convert

• codecin is the actual file format

• outfile is the path of the file you want to create

• codecout is the new file format

Be careful : outfile and codecout must be compatible. The output file extension must be a correct file extension for the new format.

Note : this verb uses FFmpeg and is not available int the LITE flavor of Flutter Sound.

Example:

        String inputFile = '$myInputPath/bar.wav';
        var tempDir = await getTemporaryDirectory();
        String outpufFile = '${tempDir.path}/$foo.mp3';
        await flutterSoundHelper.convertFile(inputFile, codec.pcm16WAV, outputFile, Codec.mp3)

pcmToWave()

Dart definition (prototype) :

Future<void> pcmToWave
(
      {
          String inputFile,
          String outputFile,
          int numChannels,
          int sampleRate,
      }
) async

This verb is usefull to convert a Raw PCM file to a Wave file.

It adds a Wave envelop to the PCM file, so that the file can be played back with startPlayer().

Note: the parameters numChannels and sampleRate are mandatory, and must match the actual PCM data. See here a discussion about Raw PCM and WAVE file format.

Example:

        String inputFile = '$myInputPath/bar.pcm';
        var tempDir = await getTemporaryDirectory();
        String outpufFile = '${tempDir.path}/$foo.wav';
        await flutterSoundHelper.pcmToWave(inputFile: inputFile, outpoutFile: outputFile, numChannels: 1, sampleRate: 8000);

pcmToWaveBuffer()

Dart definition (prototype) :

Future<Uint8List> pcmToWaveBuffer
(
      {
        Uint8List inputBuffer,
        int numChannels,
        int sampleRate,
      }
) async

This verb is usefull to convert a Raw PCM buffer to a Wave buffer.

It adds a Wave envelop in front of the PCM buffer, so that the file can be played back with startPlayerFromBuffer().

Note: the parameters numChannels and sampleRate are mandatory, and must match the actual PCM data. See here a discussion about Raw PCM and WAVE file format.

Example:

        Uint8List myWavBuffer = await flutterSoundHelper.pcmToWaveBuffer(inputBuffer: myPCMBuffer, numChannels: 1, sampleRate: 8000);

waveToPCM()

Dart definition (prototype) :

Future<void> waveToPCM
(
      {
          String inputFile,
          String outputFile,
       }
) async

This verb is usefull to convert a Wave file to a Raw PCM file.

It removes the Wave envelop from the PCM file.

Example:

        String inputFile = '$myInputPath/bar.pcm';
        var tempDir = await getTemporaryDirectory();
        String outpufFile = '${tempDir.path}/$foo.wav';
        await flutterSoundHelper.waveToPCM(inputFile: inputFile, outpoutFile: outputFile);

waveToPCMBuffer()

Dart definition (prototype) :

Uint8List waveToPCMBuffer (Uint8List inputBuffer)

This verb is usefull to convert a Wave buffer to a Raw PCM buffer. Note that this verb is not asynchronous and does not return a Future.

It removes the Wave envelop from the PCM buffer.

Example:

        Uint8List pcmBuffer flutterSoundHelper.waveToPCMBuffer(inputBuffer: aWaveBuffer);

duration()

Dart definition (prototype) :

 Future<Duration> duration(String uri) async

This verb is used to get an estimation of the duration of a sound file. Be aware that it is just an estimation, based on the Codec used and the sample rate.

Note : this verb uses FFmpeg and is not available int the LITE flavor of Flutter Sound.

Example:

        Duration d = flutterSoundHelper.duration("$myFilePath/bar.wav");

isFFmpegAvailable()

Dart definition (prototype) :

Future<bool> isFFmpegAvailable() async

This verb is used to know during runtime if FFmpeg is linked with the App.

Example:

        if ( await flutterSoundHelper.isFFmpegAvailable() )
        {
                Duration d = flutterSoundHelper.duration("$myFilePath/bar.wav");
        }

executeFFmpegWithArguments()

Dart definition (prototype) :

Future<int> executeFFmpegWithArguments(List<String> arguments)

This verb is a wrapper for the great FFmpeg application. The command "man ffmpeg" (if you have installed ffmpeg on your computer) will give you many informations. If you do not have ffmpeg on your computer you will find easyly on internet many documentation on this great program.

Example:

 int rc = await flutterSoundHelper.executeFFmpegWithArguments
 ([
        '-loglevel',
        'error',
        '-y',
        '-i',
        infile,
        '-c:a',
        'copy',
        outfile,
]); // remux OGG to CAF

getLastFFmpegReturnCode()

Dart definition (prototype) :

Future<int> getLastFFmpegReturnCode() async

This simple verb is used to get the result of the last FFmpeg command

Example:

        int result = await getLastFFmpegReturnCode();

getLastFFmpegCommandOutput()

Dart definition (prototype) :

Future<String> getLastFFmpegCommandOutput() async

This simple verb is used to get the output of the last FFmpeg command

Example:

        print( await getLastFFmpegCommandOutput() );

FFmpegGetMediaInformation

Dart definition (prototype) :

Future<Map<dynamic, dynamic>> FFmpegGetMediaInformation(String uri) async

This verb is used to get various informations on a file.

The informations got with FFmpegGetMediaInformation() are documented here.

Example:

Map<dynamic, dynamic> info = await flutterSoundHelper.FFmpegGetMediaInformation( uri );

Generated from https://highlightjs.org/download/ on 2019-05-16

Included languages:

• bash

• css

• dart

• html, xml

• java

• javascript

• json

• kotlin

• markdown

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• yaml

livePlaybackWithBackPressure

livePlaybackWithBackPressure

A very simple example showing how to play Live Data with back pressure. It feeds a live stream, waiting that the Futures are completed for each block.

This example get the data from an asset file, which is completely stupid : if an App wants to play an asset file he must use "StartPlayerFromBuffer().

If you do not need any back pressure, you can see another simple example : LivePlaybackWithoutBackPressure.dart. This other example is a little bit simpler because the App does not need to await the playback for each block before playing another one.

The complete example source is there

WidgetUIDemo

WidgetUIDemo

This is a Demo of an App which uses the Flutter Sound UI Widgets.

My own feeling is that this Demo is really too much complicated for doing something very simple. There is too many dependencies and too many sources.

I really hope that someone will write soon another simpler Demo App.

The complete example source is there

SimpleRecorder

SimpleRecorder

This is a very simple example for Flutter Sound beginners, that shows how to record, and then playback a file.

This example is really basic.

The complete example source is there

SimplePlayback

SimplePlayback

This is a very simple example for Flutter Sound beginners, that shows how to play a remote file.

This example is really basic.

The complete example source is there

soundEffect

soundEffect

startPlayerFromStream can be very efficient to play sound effects in real time. For example in a game App. In this example, the App open the Audio Session and call startPlayerFromStream() during initialization. When it want to play a noise, it has just to call the synchronous verb feed. Very fast.

The complete example source is there

Not Yet. Please come back later.

Install

For help on adding as a dependency, view the .

Flutter Sound flavors

Flutter Sound comes in two flavors :

• the FULL flavor : flutter_sound

• the LITE flavor : flutter_sound_lite

The big difference between the two flavors is that the LITE flavor does not have mobile_ffmpeg embedded inside. There is a huge impact on the memory used, but the LITE flavor will not be able to do :

• Support some codecs like Playback OGG/OPUS on iOS or Record OGG_OPUS on iOS

• Will not be able to offer some helping functions, like FlutterSoundHelper.FFmpegGetMediaInformation() or FlutterSoundHelper.duration()

Here are the size of example/demo1 iOS .ipa in Released Mode. Those numbers include everything (flutter library, application, ...) and not only Flutter Sound.

Linking your App directly from pub.dev

Add flutter_sound or flutter_sound_lite as a dependency in pubspec.yaml.

The actual versions are :

• flutter_sound_lite: ^5.0.0 (the LTS version without FFmpeg)

• flutter_sound: ^5.0.0 (the LTS version with FFmpeg embedded)

• flutter_sound_lite: ^6.0.0 (the current version without FFmpeg)

• flutter_sound: ^6.0.0 (the current version with FFmpeg)

or

Linking your App with Flutter Sound sources (optional)

The Flutter-Sound sources .

There is actually two branches :

• V5. This is the Long Term Support (LTS) branch which is maintained under the version 5.x.x

• master. This is the branch currently developed and is released under the version 6.x.x.

If you want to generate your App from the sources with a FULL flavor:

and add your dependency in your pubspec.yaml :

If you prefer to link your App with the LITE flavor :

and add your dependency in your pubspec.yaml :

FFmpeg

flutter_sound FULL flavor makes use of flutter_ffmpeg. In contrary to Flutter Sound Version 3.x.x, in Version 4.0.x your App can be built without any Flutter-FFmpeg dependency. flutter_ffmpeg audio-lts is now embedding inside the FULL flutter_sound.

If your App needs to use FFmpeg audio package, you must use the embedded version inside flutter_sound instead of adding a new dependency in your pubspec.yaml.

If your App needs an other FFmpeg package (for example the "video" package), use the LITE flavor of Flutter Sound and add yourself the App dependency that you need.

Post Installation

• On iOS you need to add usage descriptions to info.plist:

• On Android you need to add a permission to AndroidManifest.xml:

Flutter Web

To use Flutter Sound in a web application, you can either :

Static reference

Add those 4 lines at the end of the <head> section of your index.html file :

or Dynamic reference

Add those 4 lines at the end of the <head> section of your index.html file :

Please to understand how you can specify the interval of the versions you are interested by.

Troubles shooting

Problem with Cocoapods

If you get this message (specially after the release of a new Flutter Version) :

you can try the following instructions sequence (and ignore if some commands gives errors) :

If everything good, the last pod install must not give any error.

Flutter Sound is now supported by Flutter Web (with some limitations). Please to have informations on how to setup your App for web.

The big problem (as usual) is Apple. Webkit is bull shit : you cannot use MediaRecorder to record anything with it. It means that Flutter Sound on Safari cannot record. And because Apple forces Firefox and Chrome to use also Webkit on iOS, you cannot record anything on iOS with Flutter Sound. Apple really sucks :-(.

You can play with , but better if not Safari and not iOS if you want to record something.

Player

• Flutter Sound can play buffers with startPlayerFromBuffer(), exactly like with other platforms. Please refer to

• Flutter Sound can play remote URL with startPlayer(), exactly like with other platforms. Again, refer to

• Playing from a Dart Stream with startPlayerFromStream()is not yet implemented.

• Playing with UI is obviously not implemented, because we do not have control to the lock screen inside a web app.

• Flutter Sound does not have control of the audio-focus.

The web App does not have access to any file system. But you can store an URL into your local SessionStorage, and use the key as if it was an audio file. This is compatible with the Flutter Sound recorder.

Recorder

Flutter Sound on web cannot have access to any file system. You can use startRecorder() like others platforms, but the recorded data will be stored inside an internal HTTP object. When the recorder is stopped, startRecorder stores the URL of this object into your local sessionStorage.

Please refer to : Flutter Sound Recorder does not work on Safari nor iOS.

Limitations :

• Recording to a Dart Stream is not yet implemented

• Flutter Sound does not have access to the audio focus

• Flutter Sound does not provide the audio peak level in the Recorder Progress events.

FFmpeg

Actually, Flutter Sound on Web does not support FFmpeg. We are still actually not sure if we should support it or if the code weight would be too high for a Web App.

livePlaybackWithoutBackPressure

A very simple example showing how to play Live Data without back pressure. It feeds a live stream, without waiting that the Futures are completed for each block. This is simpler than playing buffers synchronously because the App does not need to await that the playback for each block is completed playing another one.

This example get the data from an asset file, which is completely stupid : if an App wants to play a long asset file he must use .

Feeding Flutter Sound without back pressure is very simple but you can have two problems :

• If your App is too fast feeding the audio channel, it can have problems with the Stream memory used.

• The App does not have any knowledge of when the provided block is really played.

  For example, if it does a "stopPlayer()" it will loose all the buffered data.

This example uses the object to resynchronize the output stream before doing a

The complete example source

streamLoop

streamLoop() is a very simple example which connect the FlutterSoundRecorder sink to the FlutterSoundPlayer Stream. Of course, we do not play to the loudspeaker to avoid a very unpleasant Larsen effect. this example does not use a new StreamController, but use directely foodStreamController from flutter_sound_player.dart.

The complete example source

Flutter Sound

Flutter Sound is the first (and actually the only) implementation of the τ Project. This Flutter plugin is supported by :

• iOS

• Android

• Flutter Web

Maybe, one day, we will be supported by Linux, Macos, and even (why not) Windows. But this is not top of our priorities.

Flutter Sound branches

We actually maintain two branches for Flutter Sound :

• The V5 branch (the version ^5.0.0)

• The master branch (actually the version ^6.0.0)

SDK requirements

• Flutter Sound requires an iOS 10.0 SDK (or later)

• Flutter Sound requires an Android 21 (or later)

Examples (Demo Apps)

Flutter Sound comes with several Demo/Examples :

is a driver which can call all the various examples.

Please, remember that actually, Flutter Sound does not support Floating Point PCM data, nor records with more that one audio channel.

To record a Raw PCM16 file, you use the regular startRecorder() API verb. To play a Raw PCM16 file, you can either add a Wave header in front of the file with pcm16ToWave() verb, or call the regular startPlayer() API verb. If you do the later, you must provide the sampleRate and numChannels parameter during the call. You can look to the simple example provided with Flutter Sound. [TODO]

Example

Recording PCM-16 to a Dart Stream

Please, remember that actually, Flutter Sound does not support Floating Point PCM data, nor records with more that one audio channel. On Flutter Sound, Raw PCM is only PCM-LINEAR 16 monophony

To record a Live PCM file, when calling the verb startRecorder(), you specify the parameter toStream: with you Stream sink, instead of the parameter toFile:. This parameter is a StreamSink that you can listen to, for processing the input data.

Notes :

• This new functionnality needs, at least, an Android SDK >= 21

• This new functionnality works better with Android minSdk >= 23, because previous SDK was not able to do UNBLOCKING write.

Example

You can look to the provided with Flutter Sound.

convertFile()

• Dart API:

This verb is useful to convert a sound file to a new format.

• infile is the file path of the file you want to convert

• codecin is the actual file format

• outfile is the path of the file you want to create

• codecout is the new file format

Be careful : outfile and codecout must be compatible. The output file extension must be a correct file extension for the new format.

Note : this verb uses FFmpeg and is not available int the LITE flavor of Flutter Sound.

Example:

</div>

How to use

First import the modules import 'flutter_sound.dart

The SoundPlayerUI provides a Playback widget styled after the HTML 5 audio player.

The player displays a loading indicator and allows the user to pause/resume/skip via the progress bar.

You can also pause/resume the player via an api call to SoundPlayerUI's state using a GlobalKey.

The SoundPlayerUI widget allows you to playback audio from multiple sources:

• File

• Asset

• URL

• Buffer

MediaFormat

When using the SoundPlayerUI you MUST pass a Track that has been initialised with a supported MediaFormat.

The Widget needs to obtain the duration of the audio that it is play and that can only be done if we know the MediaFormat of the Widget.

If you pass a Track that wasn't constructed with a MediaFormat then a MediaFormatException will be thrown.

The MediaFormat must also be natively supported by the OS. See mediaformat.md for additional details on checking for a supported format.

Example:

Sounds uses as the primary method of handing around audio data.

You can also dynamically load a Track when the user clicks the 'Play' button on the SoundPlayerUI widget. This allows you to delay the decision on what Track is going to be played until the user clicks the 'Play' button.

Playback

The complete running example is there

1. FlutterSoundPlayer instanciation

To play back something you must instanciate a player. Most of the time, you will need just one player, and you can place this instanciation in the variables initialisation of your class :

  import 'package:flauto/flutter_sound.dart';
...
  FlutterSoundPlayer _myPlayer = FlutterSoundPlayer();

2. Open and close the audio session

Before calling startPlayer() you must open the Session.

When you have finished with it, you must close the session. A good places to put those verbs are in the procedures initState() and dispose().

@override
  void initState() {
    super.initState();
    // Be careful : openAudioSession return a Future.
    // Do not access your FlutterSoundPlayer or FlutterSoundRecorder before the completion of the Future
    _myPlayer.openAudioSession().then((value) {
      setState(() {
        _mPlayerIsInited = true;
      });
    });
  }



  @override
  void dispose() {
    // Be careful : you must `close` the audio session when you have finished with it.
    _myPlayer.closeAudioSession();
    _myPlayer = null;
    super.dispose();
  }

3. Play your sound

To play a sound you call startPlayer(). To stop a sound you call stopPlayer()

void play() async {
    await _myPlayer.startPlayer(
      fromURI: _exampleAudioFilePathMP3,
      codec: Codec.mp3,
      whenFinished: (){setState((){});}
    );
    setState(() {});
  }

  Future<void> stopPlayer() async {
    if (_myPlayer != null) {
      await _myPlayer.stopPlayer();
    }
  }

Recording

The complete running example is there

1. FlutterSoundRecorder instanciation

To play back something you must instanciate a recorder. Most of the time, you will need just one recorder, and you can place this instanciation in the variables initialisation of your class :

  FlutterSoundRecorder _myRecorder = FlutterSoundRecorder();

2. Open and close the audio session

Before calling startRecorder() you must open the Session.

When you have finished with it, you must close the session. A god place to pute those verbs is in the procedures initState() and dispose().

@override
  void initState() {
    super.initState();
    // Be careful : openAudioSession return a Future.
    // Do not access your FlutterSoundPlayer or FlutterSoundRecorder before the completion of the Future
    _myRecorder.openAudioSession().then((value) {
      setState(() {
        _mRecorderIsInited = true;
      });
    });
  }



  @override
  void dispose() {
    // Be careful : you must `close` the audio session when you have finished with it.
    _myRecorder.closeAudioSession();
    _myRecorder = null;
    super.dispose();
  }

3. Record something

To record something you call startRecorder(). To stop the recorder you call stopRecorder()

  Future<void> record() async {
    await _myRecorder.startRecorder(
      toFile: _mPath,
      codec: Codec.aacADTS,
    );
  }


  Future<void> stopRecorder() async {
    await _myRecorder.stopRecorder();
  }

A number of Platforms (android/IOS) support the concept of a 'Shade' or 'notification' area with the ability to control audio playback via the Shade.

When using a Shade a Platform may also allow the user to control the media playback from the Platform's 'Lock' screen.

Using a Shade does not stop you from also displaying an in app Widget to control audio. The SoundPlayerUI widget will work in conjunction with the Shade.

The Shade may also display information contained in the Track such as Album, Artist of artwork.

A Shade often allows the user to pause and resume audio as well skip forward a track and skip backward to the prior Track.

τ allows you to enable the Shade controls when you start playback. It also allows you (where the Platform supports it) to control which of the media buttons are displayed (pause, resume, skip forward, skip backwards).

To start audio playback using the Shade use:

SoundPlayer.withShadeUI(track);

The withShadeUIconstuctor allows you to control which of the Shade buttons are displayed. The Platform MAY choose to ignore any of the button choices you make.

Skipping Tracks

If you allow the Shade to display the Skip Forward and Skip Back buttons you must provide callbacks for the onSkipForward and on onSkipBackward methods. When the user clicks the respective buttons you will receive the relevant callback.

var player = SoundPlayer.withShadeUI(track, canSkipBackward:true
    , canSkipForward:true);
player.onSkipBackwards = () => player.startPlayer(getPreviousTrack());
player.onSkipForwards = () => player.startPlayer(getNextTrack());

RecordToStream

RecordToStream

This is an example showing how to record to a Dart Stream. It writes all the recorded data from a Stream to a File, which is completely stupid: if an App wants to record something to a File, it must not use Streams.

The real interest of recording to a Stream is for example to feed a Speech-to-Text engine, or for processing the Live data in Dart in real time.

The complete example source is there

Raw PCM and Wave files

Raw PCM is not an audio format. Raw PCM files store the raw data without any envelope. A simple way for playing a Raw PCM file, is to add a Wave header in front of the data before playing it. To do that, the helper verb pcmToWave() is convenient. You can also call directely the startPlayer() verb. If you do that, do not forget to provide the sampleRate and numChannels parameters.

A Wave file is just PCM data in a specific file format.

The Wave audio file format has a terrible drawback : it cannot be streamed. The Wave file is considered not valid, until it is closed. During the construction of the Wave file, it is considered as corrupted because the Wave header is still not written.

Note the following limitations in the current Flutter Sound version :

• The stream is PCM-Integer Linear 16 with just one channel. Actually, Flutter Sound does not manipulate Raw PCM with floating point PCM data nor with more than one audio channel.

• FlutterSoundHelper duration() does not work with Raw PCM file

• startPlayer() does not return the record duration.

• withUI parameter in openAudioSession() is actually incompatible with Raw PCM files.

Supported Codecs

On mobile OS

Actually, the following codecs are supported by flutter_sound:

This table will eventually be upgraded when more codecs will be added.

• ✅ (*) : The codec is supported by Flutter Sound, but with a File Format Conversion. This has several drawbacks :

  • Needs FFmpeg. FFmpeg is not included in the LITE flavor of Flutter Sound

  • Can add some delay before Playing Back the file, or after stopping the recording. This delay can be substancial for very large records.

• ✅ (1) : needs MinSDK >=23

On Web browsers

• Webkit is bull shit : you cannot record anything with Safari, or even Firefox/Chrome on iOS.

• Opus WEBM is a great Codec. It works on everything (mobile and Web Browsers), except Apple

• Edge is same as Chrome

Raw PCM and Wave files

Raw PCM is not an audio format. Raw PCM files store the raw data without any envelope. A simple way for playing a Raw PCM file, is to add a Wave header in front of the data before playing it. To do that, the helper verb pcmToWave() is convenient. You can also call directely the startPlayer() verb. If you do that, do not forget to provide the sampleRate and numChannels parameters.

A Wave file is just PCM data in a specific file format.

The Wave audio file format has a terrible drawback : it cannot be streamed. The Wave file is considered not valid, until it is closed. During the construction of the Wave file, it is considered as corrupted because the Wave header is still not written.

Note the following limitations in the current Flutter Sound version :

• The stream is PCM-Integer Linear 16 with just one channel. Actually, Flutter Sound does not manipulate Raw PCM with floating point PCM data nor with more than one audio channel.

• FlutterSoundHelper duration() does not work with Raw PCM file

• startPlayer() does not return the record duration.

• withUI parameter in openAudioSession() is actually incompatible with Raw PCM files.

Recording or playing Raw PCM INT-Linerar 16 files

Please, remember that actually, Flutter Sound does not support Floating Point PCM data, nor records with more that one audio channel.

To record a Raw PCM16 file, you use the regular startRecorder() API verb. To play a Raw PCM16 file, you can either add a Wave header in front of the file with pcm16ToWave() verb, or call the regular startPlayer() API verb. If you do the later, you must provide the sampleRate and numChannels parameter during the call. You can look to the simple example provided with Flutter Sound. [TODO]

Example

Directory tempDir = await getTemporaryDirectory();
String outputFile = '${tempDir.path}/myFile.pcm';

await myRecorder.startRecorder
(
    codec: Codec.pcm16,
    toFile: outputFile,
    sampleRate: 16000,
    numChannels: 1,
);

...
myRecorder.stopRecorder();
...

await myPlayer.startPlayer
(
        fromURI: = outputFile,
        codec: Codec.pcm16,
        numChannels: 1,
        sampleRate: 16000, // Used only with codec == Codec.pcm16
        whenFinished: (){ /* Do something */},

);

Recording PCM-16 to a Dart Stream

Please, remember that actually, Flutter Sound does not support Floating Point PCM data, nor records with more that one audio channel. On Flutter Sound, Raw PCM is only PCM-LINEAR 16 monophony

To record a Live PCM file, when calling the verb startRecorder\(\), you specify the parameter toStream: with you Stream sink, instead of the parameter toFile:. This parameter is a StreamSink that you can listen to, for processing the input data.

Notes :

• This new functionnality needs, at least, an Android SDK >= 21

• This new functionnality works better with Android minSdk >= 23, because previous SDK was not able to do UNBLOCKING write.

Example

You can look to the simple example provided with Flutter Sound.

  IOSink outputFile = await createFile();
  StreamController<Food> recordingDataController = StreamController<Food>();
  _mRecordingDataSubscription =
          recordingDataController.stream.listen
            ((Uint8List buffer)
              {
                outputFile.add(buffer);
              }
            );
  await _mRecorder.startRecorder(
        toStream: recordingDataController.sink,
        codec: Codec.pcm16,
        numChannels: 1,
        sampleRate: 48000,
  );

Playing PCM-16 from a Dart Stream

Please, remember that actually, Flutter Sound does not support Floating Point PCM data, nor records with more that one audio channel.

To play live stream, you start playing with the verb startPlayerFromStream instead of the regular startPlayer() verb:

await myPlayer.startPlayerFromStream
(
    codec: Codec.pcm16 // Actually this is the only codec possible
    numChannels: 1 // Actually this is the only value possible. You cannot have several channels.
    sampleRate: 48100 // This parameter is very important if you want to specify your own sample rate
);

The first thing you have to do if you want to play live audio is to answer this question: Do I need back pressure from Flutter Sound, or not?

Without back pressure,

The App does just myPlayer.foodSink.add\( FoodData\(aBuffer\) \) each time it wants to play some data. No need to await, no need to verify if the previous buffers have finished to be played. All the buffers added to foodSink are buffered, an are played sequentially. The App continues to work without knowing when the buffers are really played.

This means two things :

• If the App is very fast adding buffers to foodSink it can consume a lot of memory for the waiting buffers.

• When the App has finished feeding the sink, it cannot just do myPlayer.stopPlayer(), because there is perhaps many buffers not yet played.

  If it does a stopPlayer(), all the waiting buffers will be flushed which is probably not what it wants.

But there is a mechanism if the App wants to resynchronize with the output Stream. To resynchronize with the current playback, the App does myPlayer.foodSink.add\( FoodEvent\(aCallback\) \);

myPlayer.foodSink.add
( FoodEvent
  (
     () async
     {
          await myPlayer.stopPlayer();
          setState((){});
     }
  )
);

Example:

You can look to this simple example provided with Flutter Sound.

await myPlayer.startPlayerFromStream(codec: Codec.pcm16, numChannels: 1, sampleRate: 48000);

myPlayer.foodSink.add(FoodData(aBuffer));
myPlayer.foodSink.add(FoodData(anotherBuffer));
myPlayer.foodSink.add(FoodData(myOtherBuffer));

myPlayer.foodSink.add(FoodEvent((){_mPlayer.stopPlayer();}));

With back pressure

If the App wants to keep synchronization with what is played, it uses the verb feedFromStream to play data. It is really very important not to call another feedFromStream() before the completion of the previous future. When each Future is completed, the App can be sure that the provided data are correctely either played, or at least put in low level internal buffers, and it knows that it is safe to do another one.

Example:

You can look to this example and this example

await myPlayer.startPlayerFromStream(codec: Codec.pcm16, numChannels: 1, sampleRate: 48000);

await myPlayer.feedFromStream(aBuffer);
await myPlayer.feedFromStream(anotherBuffer);
await myPlayer.feedFromStream(myOtherBuffer);

await myPlayer.stopPlayer();

You probably will await or use then() for each call to feedFromStream().

Notes :

• This new functionnality needs, at least, an Android SDK >= 21

• This new functionnality works better with Android minSdk >= 23, because previous SDK was not able to do UNBLOCKING write.

Examples You can look to the provided examples :

• This example shows how to play Live data, with Back Pressure from Flutter Sound

• This example shows how to play Live data, without Back Pressure from Flutter Sound

• This example shows how to play some real time sound effects.

• This example play live stream what is recorded from the microphone.

Not yet. Please come back later.

Flutter Sound is a free and Open Source project. Several contributors have already contributed to Flutter Sound. Specially :

• @hyochan who is the Flutter Sound father

• @salvatore373 who wrote the Track Player

• @bsutton who wrote the UI Widgets

• @larpoux who add several codec supports