Desktop Flutter View Recorder

Features

• Start/stop recording
• Query current recording state
• Control FPS
• Reduce output resolution with resolutionDivisor

Platform Support

Platform	Backend	Output
macOS	NSView (Flutter view) frame capture + AVAssetWriter (H.264)	.mp4
Windows	GDI capture of Flutter native view handle + Media Foundation (H.264)	.mp4
Linux	GTK/GDK capture of FlView widget (fallback: root window) + internal AVI writer	.avi

Get Started

1. Add dependency

dependencies:
  recaster: ^0.1.1

2. Install

flutter pub get

3. Import

import 'package:recaster/recaster.dart';

API

Future<void> startRecording({
  required String outputPath,
  int fps = 30,
  int resolutionDivisor = 1,
});

Future<String?> stopRecording();
Future<bool> isRecording();

Parameters

• outputPath: target file path
• fps: capture rate, typical range 15..60
• resolutionDivisor:
  • 1 = original window size
  • 2 = half width/height
  • 3 = one-third width/height

Usage Example

import 'package:recaster/recaster.dart';

final recaster = Recaster();

await recaster.startRecording(
  outputPath: '/tmp/recording.mp4', // use .avi on Linux
  fps: 30,
  resolutionDivisor: 2,
);

final recording = await recaster.isRecording();
final savedPath = await recaster.stopRecording();

Important Notes

• Recording target is Flutter view content on all desktop platforms.
• startRecording validates output path before capture starts.
• Always call stopRecording() to finalize and flush the output file.

Platform Notes

macOS

• Capture source: Flutter view via NSView frame capture.
• Output format: .mp4 (H.264, via AVAssetWriter).
• If app sandbox is enabled, writing to arbitrary paths may be restricted by entitlements.

Windows

• Capture source: Flutter native view handle via GDI.
• Output format: .mp4 (H.264, via Media Foundation).

Linux

• Capture source: FlView widget via GTK/GDK (root window fallback).
• Output format: .avi (internal AVI writer).
• AVI output is uncompressed and can be large.

Path Validation Errors

startRecording can return clear platform errors for invalid output paths:

• invalid_output_path
• directory_create_failed
• path_not_writable

Use these codes to handle invalid output path configuration in your app.

Usage Recommendations

• Always pass an absolute outputPath.
• Create unique output file names to avoid overwriting previous recordings.
• Keep resolutionDivisor > 1 for long runs to reduce size.
• Always call stopRecording() to finalize the output file.

Troubleshooting

• stop_failed on macOS often means permission/path issues.
• If file is missing after stop, verify:
  • final path exists
  • process has write access
  • correct extension per platform