Utilities topic

title: "Utilities API" description: "The τ utilities API." summary: "The τ Project offers several helper utilities." permalink: tau_api_utilities tags: api,utilities,helpers keywords: API, utilities, helpers

Flutter Sound Helpers API

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 );