Send real-time PCM audio (16-bit integer) to your device speakers, from your Flutter app!

No Dependencies

FlutterPcmSound has zero dependencies besides Flutter, Android, iOS, and MacOS themselves.

Not for Audio Files

Unlike other plugins, flutter_pcm_sound does not use audio files (For example: sound_pool).

Instead, flutter_pcm_sound is for apps that generate audio in realtime a few milliseconds before you hear it. For example, using dart_melty_soundfont.

Callback Based, For Real-Time Audio

In contrast to raw_sound, FlutterPcmSound uses a callback setFeedCallback to signal when to feed more samples.

You can lower the feed threshold using setFeedThreshold to achieve real time audio, or increase it to have a cushy buffer.

Event Based Feeding

Unlike traditional audio libraries which use a high-frequency timer-based audio callback, flutter_pcm_sound uses a low-frequency event-based callback. This integrates more seamlessly in the existing Flutter event loop, without necessitating an Isolate to ensure precise timing.

Your feed callback is invoked once for each of these events:

• Low-buffer event – when the number of buffered frames falls below the threshold set with setFeedThreshold.
• Zero event – when the buffer is fully drained (remainingFrames == 0).

Note: once means once per feed() — every time you feed new data, the plugin will trigger another low-buffer or zero event when necessary.

💡 Tip: By altering how many extra samples you feed beyond your threshold, you can control how often flutter_pcm_sound invokes your feed callback.

💡 Tip: If you prefer, it's easy to wrap flutter_pcm_sound to simulate traditional timer-based feeding. 1) set a large feed threshold so that flutter_pcm_sound regularly tells you its remainingFrames 2) start a Dart-side Timer.periodic(...) or Ticker 3) use that timer to invoke a new feed callback and pass it the remainingFrames minus the elapsed time since the original callback.

💡 Tip: Consider running your sound code in a Dart Isolate, so that it is decoupled from UI framedrops.

One-Pedal Driving

To play audio, just keep calling feed.

To stop audio, just stop calling feed.

🧠 Why no start & stop functions? two reasons. 1) unlike a timer-based API, in an event-based API there's no audio callback thread you need to "start". You just feed when the events arrive. 2) In Flutter, calling native is always async. If playback depended on await start() and await stop(), you’d have additional, needless delays which can lead to stuttery audio. By using a simple "just feed" approach, we avoid this.

💡 Tip: If you prefer a traditional timer-based API with start() and stop(), I recommend wrapping flutter_pcm_sound as described in the Event-Based Feeding tips.

Is Playing?

When your feed callback hits remainingFrames=0 you know playing stopped.

Usage

// for testing purposes, a C-Major scale 
MajorScale scale = MajorScale(sampleRate: 44100, noteDuration: 0.25);

// invoked whenever we need to feed more samples to the platform
void onFeed(int remainingFrames) async {
    // you could use 'remainingFrames' to feed very precisely.
    // But here we just load a few thousand samples everytime we run low.
    List<int> frame = scale.generate(periods: 20);
    await FlutterPcmSound.feed(PcmArrayInt16.fromList(frame));
}

await FlutterPcmSound.setup(sampleRate: 44100, channelCount: 1);
await FlutterPcmSound.setFeedThreshold(8000); 
FlutterPcmSound.setFeedCallback(onFeed);
FlutterPcmSound.start(); // for convenience. Equivalent to calling onFeed(0);

⭐ Stars ⭐

Please star this repo & on pub.dev. We all benefit from having a larger community.

Example App

Enable the platforms you need.

cd ./example                      
flutter config --enable-macos-desktop                                                      
flutter config --enable-android 
flutter config --enable-ios 
flutter create .
flutter run