flutter_uvc_camera

A Flutter plugin based on AndroidUSBCamera to enable Flutter apps to use external UVC cameras.

pub：flutter_uvc_camera

Features

  • Connect to and control external UVC cameras through USB
  • Display camera preview in your Flutter app
  • Take photos and save to local storage
  • Record videos with time tracking
  • Stream video frames (H264) and audio frames (AAC) for further processing
  • Control camera features like brightness, contrast, focus, etc.
  • Monitor camera connection status
  • Support for different preview resolutions

Limitations

  • Currently, only supports Android
  • For Android 10+, you may need to reduce targetSdkVersion to 27
  • Some device models may have compatibility issues (e.g., Redmi Note 10)

Installation

1. Add Dependency

Add the flutter_uvc_camera plugin dependency to your Flutter project's pubspec.yaml file:

dependencies:
  flutter_uvc_camera: ^latest_version

2. Configure Android Project

Add Permissions

Add the following permissions to the AndroidManifest.xml file of your Android project:

<uses-permission android:name="android.permission.USB_PERMISSION" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-feature android:name="android.hardware.usb.host" />
<uses-feature android:name="android.hardware.camera"/>
<uses-feature android:name="android.hardware.camera.autofocus"/>

Add Repository

In your project's android/build.gradle, add the JitPack repository:

allprojects {
    repositories {
        // other repositories
        maven { url "https://jitpack.io" }
    }
}

Configure USB Device Detection

Add an action for USB device connection in the intent-filter of your main Activity, and reference the corresponding XML file in meta-data:

<intent-filter>
    <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
</intent-filter>
<meta-data
    android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
    android:resource="@xml/device_filter" />

Create the device_filter.xml file in the android/app/src/main/res/xml/ directory:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <!-- USB device vendor-id and product-id values for your camera -->
    <!-- You can use wildcard configuration below or specify your camera IDs -->
    <usb-device vendor-id="1234" product-id="5678" class="255" subclass="66" protocol="1" />
</resources>

3. Configure ProGuard (for release mode)

If you're building in release mode with minification enabled, add these rules to your android/app/proguard-rules.pro:

-keep class com.jiangdg.uvc.UVCCamera {
    native <methods>;
    long mNativePtr;
}
-keep class com.jiangdg.uvc.IStatusCallback {
    *;
}
-keep interface com.jiangdg.uvc.IButtonCallback {
    *;
}

And update your android/app/build.gradle:

buildTypes {
    release {
        // your existing configs
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        minifyEnabled true
    }
}

Usage

Basic Usage

import 'package:flutter/material.dart';
import 'package:flutter_uvc_camera/flutter_uvc_camera.dart';

class CameraScreen extends StatefulWidget {
  @override
  State<CameraScreen> createState() => _CameraScreenState();
}

class _CameraScreenState extends State<CameraScreen> {
  late UVCCameraController cameraController;
  bool isCameraOpen = false;

  @override
  void initState() {
    super.initState();
    cameraController = UVCCameraController();
    
    // Set up camera state callback
    cameraController.cameraStateCallback = (state) {
      setState(() {
        isCameraOpen = state == UVCCameraState.opened;
      });
    };
  }

  @override
  void dispose() {
    cameraController.closeCamera();
    cameraController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('UVC Camera')),
      body: Column(
        children: [
          // Camera preview
          Container(
            height: 300,
            child: UVCCameraView(
              cameraController: cameraController,
              width: 300, 
              height: 300,
            ),
          ),
          
          // Camera control buttons
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: [
              ElevatedButton(
                onPressed: isCameraOpen ? null : () => cameraController.openUVCCamera(),
                child: Text('Open Camera'),
              ),
              ElevatedButton(
                onPressed: isCameraOpen ? () => cameraController.closeCamera() : null,
                child: Text('Close Camera'),
              ),
              ElevatedButton(
                onPressed: isCameraOpen ? () => takePicture() : null,
                child: Text('Take Picture'),
              ),
            ],
          ),
        ],
      ),
    );
  }

  Future<void> takePicture() async {
    final path = await cameraController.takePicture();
    if (path != null) {
      print('Picture saved at: $path');
    }
  }
}

Video Recording

// Start recording a video
Future<void> recordVideo() async {
  final path = await cameraController.captureVideo();
  print('Video saved at: $path');
}

Video Streaming

// Set up frame callbacks
cameraController.onVideoFrameCallback = (frame) {
  // Process H264 encoded video frame
  // frame.data contains the encoded data
  // frame.timestamp contains the timestamp
  // frame.size contains the size in bytes
  // frame.fps contains the current frame rate
};

cameraController.onAudioFrameCallback = (frame) {
  // Process AAC encoded audio frame
};

// Start streaming
cameraController.captureStreamStart();

// Stop streaming
cameraController.captureStreamStop();

Camera Features Control

// Set auto focus
await cameraController.setAutoFocus(true);

// Set zoom level
await cameraController.setZoom(5);

// Set brightness
await cameraController.setBrightness(128);

// Get all camera features
final features = await cameraController.getAllCameraFeatures();

API Reference

UVCCameraController

The main controller class for interacting with the UVC camera.

Properties

  • cameraStateCallback: Callback for camera state changes
  • msgCallback: Callback for messages from the camera
  • clickTakePictureButtonCallback: Callback when the camera's physical button is pressed
  • onVideoFrameCallback: Callback for video frame data
  • onAudioFrameCallback: Callback for audio frame data
  • onRecordingTimeCallback: Callback for recording time updates
  • onStreamStateCallback: Callback for stream state changes

Methods

  • initializeCamera(): Initialize the camera
  • openUVCCamera(): Open the UVC camera
  • closeCamera(): Close the UVC camera
  • captureStreamStart(): Start capturing video stream
  • captureStreamStop(): Stop capturing video stream
  • takePicture(): Take a photo and save to storage
  • captureVideo(): Start/stop video recording
  • setVideoFrameRateLimit(int fps): Limit the frame rate
  • setVideoFrameSizeLimit(int maxBytes): Limit the frame size
  • getAllPreviewSizes(): Get available preview sizes
  • updateResolution(PreviewSize size): Update camera resolution
  • setCameraFeature(String feature, int value): Set camera feature value
  • resetCameraFeature(String feature): Reset camera feature to default

UVCCameraView

Widget to display the camera preview.

Properties

  • cameraController: The UVCCameraController instance
  • width: The width of the view
  • height: The height of the view
  • params: Optional parameters for camera initialization
  • autoDispose: Whether to automatically dispose the camera when the view is disposed

Common Issues

Release Mode Build Failure

If you encounter NoSuchMethodError when running in release mode, make sure you've properly configured ProGuard rules as described in the installation section.

USB Permission Issues

If the camera is not being detected, check that:

  1. Your device supports USB OTG
  2. You've correctly configured the USB device filter
  3. You have proper permissions declarations in AndroidManifest.xml

Example

For a complete example, check the example project.

License

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

Issue Reporting

If you encounter any problems or have any suggestions during usage, please report them on GitHub Issues.

Libraries

flutter_uvc_camera