flutter_story_encoder 1.1.5

A production-grade, hardware-accelerated video export engine for Flutter. Specifically designed for high-scale social media story editors requiring premium performance, thermal stability, and 4K capability.

flutter_story_encoder

A production-grade, hardware-accelerated video export engine for Flutter. Specifically designed for high-scale social media story editors requiring premium performance, thermal stability, and 4K capability.

Features

• Hardware Accelerated: Uses iOS AVFoundation and Android MediaCodec with Surface input for native-speed encoding.
• Zero-Copy Pipeline: Optimized GPU-backed frame transfers on both platforms.
• Thermal Stability: Built-in backpressure management to prevent device overheating during long exports.
• Deterministic Pacing: Precise frame timestamping for professional-grade, jitter-free video output.
• Type-Safe IPC: Leverages Pigeon for efficient, compile-time safe communication between Dart and Native code.
• Stats Streaming: Real-time telemetry for frames processed, throughput (FPS), and progress.

Platform Support

Feature	iOS (AVFoundation)	Android (MediaCodec)
Hardware Encoding	✅	✅
H.264 (AVC)	✅	✅
High Profile 4.1	✅	✅
4K @ 60fps	✅	✅
Silent Audio	✅	✅
Backpressure	✅	✅

Getting Started

Installation

Add flutter_story_encoder to your pubspec.yaml:

dependencies:
  flutter_story_encoder: ^1.1.5

iOS Requirements

• iOS 13.0+
• Add following keys to Info.plist if you intend to save directly to library (optional for preview):

<key>NSPhotoLibraryAddUsageDescription</key>
<string>We need permission to save your stories.</string>

Android Requirements

• Min SDK 21+ (Lollipop)
• Recommended Min SDK 24+ for stable 4K Surface encoding.

Usage

Simple Export

final bool started = await FlutterStoryEncoder.start(
  config: EncoderConfig(
    width: 1080,
    height: 1920,
    fps: 30,
    bitrate: 10000000, // 10 Mbps
    outputPath: '/path/to/output.mp4',
    addSilentAudio: true,
  ),
  onProgress: (stats) {
    print("Progress: ${stats.progress}% - FPS: ${stats.currentFps}");
  },
  onError: (msg, code) => print("Error [$code]: $msg"),
);

// Capture frames from a RepaintBoundary
final image = await boundary.toImage();
final byteData = await image.toByteData(format: ui.ImageByteFormat.rawRgba);
await FlutterStoryEncoder.appendFrame(byteData.buffer.asUint8List());

final String? finalPath = await FlutterStoryEncoder.finish();

Performance Tuning

For the best results in high-scale apps:

1. Resolution: Match your RepaintBoundary pixel ratio to the target resolution to avoid expensive software scaling.
2. Bitrate: 10-15 Mbps is recommended for 1080p high-quality stories.
3. Pacing: Use Future.delayed(Duration.zero) between frame captures to allow the Flutter UI thread to breathe.

Technical Specifications

• Video Codec: H.264 / AVC
• Audio Codec: AAC (Silent track for compatibility)
• Profile: High Profile 4.1
• Keyframe Interval: 1 second
• Rate Control: VBR (Variable Bitrate) with target matching
• Color Space: BT.709

License

This project is licensed under the MIT License - see the LICENSE file for details.