flutter_pcm_sound 3.3.1

Send real-time PCM audio (16-bit integer) to your device speakers

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.

Web

Web support is available on this fork by @keyur2maru

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

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, it allows the plugin to trigger another low-buffer or zero event.

🧠 Why event-based feeding? You might wonder why flutter_pcm_sound doesn’t just use a timer to request more samples every few milliseconds like every other audio library. The problem is asynchronous timing. Whether the timer runs on the Dart or native side, your feed callbacks get bunched up behind Dart UI work, leading to audio delays, pops, & excess work, and means it's not really a reliable "timer". Event-based better reflects the reality of Dart timing without requiring an isolate, and is more efficient.

💡 Tip: You can still emulate timer-style feeding by setting a very large feed threshold so that flutter_pcm_sound calls your feed callback regularly. From there, you can also optionally run a Dart-side Timer.periodic(...) or Ticker and estimate remainingFrames from your last callback + the elapsed time since it fired. You should also consider running this in a Dart Isolate.

One-Pedal Driving

To play audio, just keep calling feed.

To stop audio, just stop calling feed.

🧠 Why no start & stop functions? In Flutter, every call that touches the native side happens asynchronously. If playback depended on await start() and await stop(), you’d always have to deal with timing jitter between Dart and native while adding additional, needless delay. Instead, flutter_pcm_sound takes a simpler approach better suited for event-based feeding: feed() does everything. Feeding begins playback if needed and seamlessly continues until the buffer is empty — i.e. until the feed callback is invoked with remainingFrames = 0. If you really want a stop() function, you can easily wrap flutter_pcm_sound so that feed() becomes a no-op while “stopped”, which will cause playback to naturally end. This library is designed to be extended and built upon, and you can wrap the API with more traditional timer-based functions (start/stop/onFeed) if you prefer.

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