flutter_soloud

The example directory contains several implementations demonstrating the capabilities of flutter_soloud. Use these as templates for your own implementation:

Basic Usage

• Basic Setup: lib/main.dart shows the fundamental initialization and usage.
• Output Devices: lib/output_device/output_device.dart demonstrates how to list and select available audio output devices.

Audio Visualization

• Audio Data: lib/audio_data/audio_data.dart shows how to use AudioData for visualization.
• Waveform Data: lib/wave_data/wave_data.dart demonstrates reading and displaying audio samples from files.

Advanced Features

• Audio Generation: Real-time waveform control (lib/waveform/waveform.dart) and precise metronome creation (lib/metronome/metronome.dart).
• Streaming: Generating PCM audio in an Isolate (lib/buffer_stream/generate.dart) or streaming PCM/Opus audio via WebSockets (lib/buffer_stream/websocket.dart).

Audio Effects

• Compressor: Dynamic range compression (lib/filters/compressor.dart).
• Limiter: Peak limiting and volume control (lib/filters/limiter.dart).
• Pitch Shifting: Real-time pitch shifting (lib/filters/pitchshift.dart).

Managing the lifecycle of a sound (especially fixed-length sounds):

• Starting/Seeking: Use .seek(inputBuffers, inputSamples, playbackRateHint) to move through audio. For the very first block (or after a .reset()), it is recommended to call .seek() with inputSamples = stretch.inputLatency() to align processing time with the start of the input.
• Ending (Fixed-length sounds): When input runs out, you may still have pending output.
  1. Pass an additional .inputLatency() samples of silence to .process() to ensure the processing time reaches the end.
  2. Use .flush(outputBuffers, outputSamples) to read the final remaining output. It is recommended to read at least .outputLatency() samples.

// Seeking
stretch.seek(inputBuffers, inputSamples, playbackRateHint);

// Ending a fixed-length sound
// 1. Feed silence to reach the end
float **silence = ...;
stretch.process(silence, stretch.inputLatency(), outputBuffers, outputSamples);

// 2. Flush remaining output
stretch.flush(outputBuffers, outputSamples);

To use the library, include signalsmith-stretch.h and instantiate signalsmith::stretch::SignalsmithStretch<T>.

Configuration can be done via presets or manual configuration:

• Presets: Use .presetDefault(channels, sampleRate) for standard settings or .presetCheaper(channels, sampleRate) for lower computational cost.
• Manual: Use .configure(channels, blockSamples, intervalSamples) to specify custom block and interval sizes. You can query the current settings using .blockSamples() and .intervalSamples().

Both preset and configure methods accept an optional splitComputation flag. When enabled, this spreads computation out more evenly by introducing one extra interval of output latency, which can help in strict real-time environments.

#include "signalsmith-stretch.h"

signalsmith::stretch::SignalsmithStretch<float> stretch;

// Using presets
stretch.presetDefault(2, 44100);

// Manual configuration
stretch.configure(2, 512, 128);

To use flutter_soloud, you must first access the singleton instance via SoLoud.instance and call init() before performing any audio operations. When finished with the audio engine, call deinit() to release resources.

You can play sounds in two ways:

1. Directly from an asset: Use playSource(asset: ...) for quick playback.
2. Pre-loading a sound: Use loadAsset(...) to get a Sound object, then use play(sound) to get a SoundHandle. This is more efficient for sounds that will be played multiple times.

import 'package:flutter_soloud/flutter_soloud.dart';

void example() async {
  final soloud = SoLoud.instance;
  await soloud.init();

  // Option 1: Play directly from asset
  await soloud.playSource(asset: 'assets/sound.mp3');

  // Option 2: Pre-load and play
  final sound = await soloud.loadAsset('assets/sound.mp3');
  final handle = soloud.play(sound);
  
  // ... perform audio operations ...

  soloud.deinit();
}