flutter_gapless_loop 0.0.6

True sample-accurate gapless audio looping on iOS, Android, macOS, and Windows. Zero-gap, zero-click loop playback for music production apps.

0.0.6

Bug fixes

• Multi-engine AVAudioSession conflict (iOS). When two LoopAudioPlayer instances are used concurrently (e.g. a drone pad and a loop player), every loadFile call on a new engine previously re-ran AVAudioSession.setCategory(.playback) + setActive(true) on the shared session. Reconfiguring the shared AVAudioSession while another AVAudioEngine is actively running triggers an AVAudioEngineConfigurationChange notification that invalidates the running engine, causing the second player's engine.start() to fail. Fixed by guarding setCategory/setActive behind a private static var sessionConfigured flag — the session is configured exactly once per process lifetime, regardless of how many engines are created. Each engine instance still registers its own interruptionNotification and routeChangeNotification observers independently. The static flag is reset in detachFromEngine(for:) so a hot restart correctly reconfigures the session for the next engine lifecycle.

0.0.5

Bug fixes

• clearAll unhandled exception on startup. On every cold start and hot restart the Dart constructor called clearAll on the native engine map (a fire-and-forget method with no playerId). On Android, iOS, and macOS the playerId guard ran unconditionally at the top of onMethodCall / handle(_:result:) and handleMetronomeCall, so clearAll was rejected with PlatformException(INVALID_ARGS, 'playerId' is required) before it could be dispatched. Because the call is fire-and-forget the error surfaced as an unhandled exception: two per launch (one from LoopAudioPlayer, one from MetronomePlayer). Fixed by handling clearAll as an early-return before the playerId guard in all three platforms (Android, iOS, macOS). The now-unreachable duplicate clearAll cases inside the when/switch blocks were removed.

0.0.4

New platforms

• macOS support. Full implementation using AVAudioEngine + AVAudioUnitTimePitch, matching the iOS engine. Audio session is replaced by AVAudioEngineConfigurationChange notifications. Minimum macOS version: 11.0.
• Windows support. Full implementation using XAudio2 2.9 (Windows 10+) + MediaFoundation decoding. All four playback modes (full/region × with/without crossfade) are supported. Beat-accurate metronome via XAudio2 + std::chrono timer. BPM/time-signature detection ported in C++. Audio device changes handled via IMMNotificationClient.

Bug fixes

• Hot-restart guard. A static bool _didClearAll flag fires clearAll on the native engine map the first time a LoopAudioPlayer or MetronomePlayer is constructed after a Dart hot restart. This prevents stale native engines from a previous Dart generation leaking into the new session. All four native platforms (iOS, Android, macOS, Windows) handle the clearAll call on both the loop and metronome channels.
• GC-based dispose safety net. LoopAudioPlayer and MetronomePlayer now register a Finalizer<String> that fires a native dispose call if the Dart object is garbage-collected without an explicit dispose(). Instances are tracked in a Set<WeakReference<T>> so they do not prevent collection. The _forEachLive helper in LoopAudioMaster / MetronomeMaster lazily removes stale weak references during group-bus operations.

Performance improvements

• Android: async MediaCodec decode. AudioFileLoader now uses MediaCodec.Callback (async mode) instead of a synchronous poll loop with a 10 ms dequeue timeout. Codec buffer callbacks fire immediately when the hardware is ready, eliminating hundreds of unnecessary spin cycles on longer files. Biggest win on files ≥ 10 seconds.
• Android: pre-allocated PCM buffer. The decoded PCM output is now pre-allocated from the track duration estimate (+ 10% headroom for encoder padding) and written into directly, replacing the previous ArrayList<FloatArray> collect-then-copy pattern. This cuts peak memory usage and eliminates one full-size FloatArray copy per load.

New features

• LoopAudioPlayer.amplitudeStream. A new Stream<AmplitudeEvent> that emits real-time audio level data approximately 20 times per second while the player is in PlayerState.playing. Each AmplitudeEvent carries:

  • rms — root-mean-square level of the most recent audio buffer rendered by the native engine, in [0.0, 1.0]. Smooth signal; well-suited for VU meters.
  • peak — peak sample magnitude of the same buffer, in [0.0, 1.0]. Reacts faster than rms; use for peak-hold indicators.

  The stream emits no events when playback is paused or stopped. Both iOS and Android compute RMS and peak in the native render thread and post events via the existing EventChannel.

• LoopAudioMaster. A new static group-bus controller for all live LoopAudioPlayer instances. setVolume scales every instance multiplicatively (effectiveVolume = localVolume × masterVolume); setPan shifts every instance additively (effectivePan = clamp(localPan + masterPan, −1, 1)). reset() restores defaults and re-applies. Per-instance relative levels are preserved at the Dart layer — native engines receive only the final effective float.

• MetronomeMaster. Same group-bus pattern for all live MetronomePlayer instances.

• MetronomePlayer.setVolume / setPan. New per-instance volume and pan control on MetronomePlayer. Effective values are computed multiplicatively with MetronomeMaster before being sent to native. iOS: AVAudioEngine.mainMixerNode.volume / .pan, re-applied after every setupAndPlay rebuild. Android: AudioTrack.setStereoVolume via panToGains, re-applied after every playBarBuffer rebuild.

Breaking changes

• LoopAudioPlayer.setVolume previously threw ArgumentError for values outside [0.0, 1.0]; it now silently clamps to be consistent with setPan and the new master API.

0.0.3

New features

• Multi-instance support. Any number of LoopAudioPlayer and MetronomePlayer instances can run concurrently without cross-talk. Each instance receives a unique playerId ('loop_N' / 'metro_N') injected into every method channel call. Events are tagged with the same ID so the Dart layer filters them per-instance using a shared broadcast stream.
• MetronomePlayer. A new class that drives a sample-accurate click track independent of LoopAudioPlayer. Pre-generates a single-bar PCM buffer (accent on beat 0, regular clicks on beats 1…N-1) and loops it via the native hardware scheduler. Beat-tick events emitted per beat for UI synchronisation. API: start, stop, setBpm, setBeatsPerBar, beatStream, dispose.
• loadFromUrl(Uri). Downloads and loads audio from an HTTP/HTTPS URL using the native networking stack (URLSession on iOS, HttpURLConnection on Android) — no third-party packages required.
• loadFromBytes(Uint8List). Loads audio from in-memory bytes by writing to a temporary file, loading it, and cleaning up immediately.
• Automatic time signature detection. BpmResult now includes beatsPerBar (int) and bars (List<double>) in addition to bpm, confidence, and beats.
• Pitch-preserving playback rate (setPlaybackRate) — time-stretch from 0.25× to 4×.

Native engine changes

• iOS: MetronomeEngine uses its own AVAudioEngine + AVAudioPlayerNode. Bar buffer is built with buildBarBuffer(bpm:beatsPerBar:) and looped via scheduleBuffer(.loops). Beat ticks fire via DispatchSourceTimer on .main. Plugin bridge now holds [String: LoopAudioEngine] and [String: MetronomeEngine] registries.
• Android: MetronomeEngine uses AudioTrack MODE_STATIC + setLoopPoints for hardware-level looping. Bar buffer is built via buildBarBuffer() (companion object — unit-testable). Beat ticks fire via Handler. Plugin bridge now holds HashMap<String, LoopAudioEngine> and HashMap<String, MetronomeEngine> registries.

Breaking changes

• loadFromUrl no longer accepts an httpClient parameter (native networking is used instead).
• All method channel payloads now include a playerId key. Custom native-side integrations must be updated to extract and route by this key.

Dependencies

• Removed http: ^1.2.0 (no longer needed).

0.0.2

• loadFromUrl now downloads via the platform networking stack (URLSession on iOS, HttpURLConnection on Android) instead of Dart's HTTP client. No third-party packages required.
• URL scheme is validated natively (http/https only); invalid schemes return PlatformException(INVALID_ARGS).
• Temp files for URL downloads use UUID names and are always cleaned up, including on coroutine cancellation (Android) and write failure (iOS).

0.0.1

• Initial release.
• Sample-accurate gapless looping on iOS (AVAudioEngine) and Android (AudioTrack).
• Configurable loop region (start/end in seconds).
• Optional equal-power crossfade between loop iterations.
• Volume control and seek support.
• Stereo pan control (setPan).
• Pitch-preserving playback rate / time-stretching (setPlaybackRate).
• Automatic BPM/tempo detection after every load (bpmStream, BpmResult).
• stateStream, errorStream, routeChangeStream, and bpmStream for reactive UI.
• Audio route change events (e.g. headphones unplugged).