Overview

coast_audio_miniaudio is an extension package for coast_audio using miniaudio.
You can use this package to implement audio capture, playback and many other audio capabilities on Android, iOS and macOS.

Features

• Audio Capture and Playback
  • Core Audio(iOS/macOS), OpenSL ES(Android) and AAudio(Android) are supported
• Device Enumeration
• PCM Format Conversion
• Filtering
  • HPF, LPF, HSF, LSF, and PeakingEQ filters
• Decoding
  • MP3, FLAC and WAV formats
• Encoding
  • WAV format

Setup

This package calls native functions by using ffi.
To do so, you have to link the mabridge library into your application.

Prebuilt binaries are located at mabridge/prebuilt.

If you are a Flutter user, use the flutter_coast_audio_miniaudio package which handles this setup step automatically.

MabDevice

MabDevice is an abstract class for interacting audio devices by using ma_device and ma_context APIs.
For capturing, use the MabCaptureDevice and for playback, use the MabPlaybackDevice.

A default audio device will be used if no device parameter is specified.

This example plays the loopback audio for 10 seconds.

MabDeviceContext.enableSharedInstance(
    backends: [
        MabBackend.coreAudio, // Use the Core Audio backend for iOS/macOS
        MabBackend.aaudio, // Use the AAudio backend for Android
    ],
);

const format = AudioFormat(sampleRate: 48000, channels: 2);

final captureDevice = MabCaptureDevice(
    context: MabDeviceContext.sharedInstance, // You should use the same device context on all MabDevice instances.
    format: format,
    bufferFrameSize: 2048, // bufferFrameSize will be used to store the captured data. For low-latency use cases, set this field to smaller size.
);

final playbackDevice = MabPlaybackDevice(
    context: MabDeviceContext.sharedInstance,
    format: format,
    bufferFrameSize: 2048,
);

// Initialize nodes.
final captureNode = MabCaptureDeviceNode(device: captureDevice);
final playbackNode = MabPlaybackDeviceNode(device: playbackDevice);
final graphNode = GraphNode();

// Connect nodes.
graphNode.connect(captureNode.outputBus, playbackNode.inputBus);
graphNode.connectEndpoint(playbackNode.outputBus);

// Start input and output devices.
captureDevice.start();
playbackDevice.start();

final task = AudioTask(
    clock: AudioIntervalClock(const Duration(milliseconds: 16)),
    format: format,
    framesRead: 2048,
    endpoint: graphNode.outputBus,
);

// Start reading audio periodically.
task.start();

// Wait for 10 seconds.
await Future<void>.delayed(const Duration(seconds: 10));

// Dispose all resources.
task.dispose();
captureDevice.dispose();
playbackDevice.dispose();

MabAudioDecoder

MabAudioDecoder is a decoder class for decoding mp3, flac and wav data from a file by using ma_decoder API.
This class implements an AudioDecoder abstract class so you can use it on the DecoderNode.

final dataSource = AudioFileDataSource(file: File('example.mp3'), mode: FileMode.read);
final decoder = MabAudioDecoder(
  dataSource: dataSource,
  outputFormat: _player.format,
);
final decoderNode = DecoderNode(decoder: decoder);

// do some stuff...

decoderNode.dispose();
decoder.dispose();
dataSource.dispose();

Filtering

These filters are supported in this package.

• Low/High Pass Filter
• Low/High Shelf Filter
• Peaking EQ Filter

You can initialize the MabFilterNode instance by passing a filter above.

final node = MabFilterNode(
  format: format,
  filter: MabPeakingEQFilter(format: format, gainDb: 5, q: 1, frequency: 1000),
);