skio_uvc_camera 0.1.0-beta.1

USB Video Class (UVC) camera for Flutter on Android (USB OTG) and web: live preview, JPEG capture and the camera's hardware button. Part of skio.

skio_uvc_camera

USB Video Class (UVC) cameras for Flutter: endoscopes, microscopes, inspection cameras and USB webcams. Live preview, JPEG capture and the camera's own hardware button, on Android (USB OTG) and the web. Part of the skio family.

Beta. The API may still change before 0.1.0. The Android and web backends have not been tested with a real UVC camera yet. If you try it, please open an issue with your camera, phone or browser, and SkioLog output (SkioLog.level = LogLevel.debug; SkioLog.records.listen(print);).

import 'package:skio_uvc_camera/skio_uvc_camera.dart';

final cameras = await UvcCamera.devices();
final access = await UvcCamera.access.requestAccess(cameras.first);
if (!access.isUsable) return;

final cam = await UvcCamera.open(
  cameras.first,
  // Cheap cameras often only do 1280x720 and 640x480, so list fallbacks.
  preferred: const [UvcSize(1920, 1080), UvcSize(1280, 720)],
);

// In build():
UvcPreview(camera: cam);

final XFile jpeg = await cam.capture(quality: 95);
cam.buttonPresses.listen((_) => cam.capture()); // the camera's own button
await cam.close();

Features

• One call for permissions: UvcCamera.access.requestAccess(device)
• Choose a preview size from what the camera really supports (supportedSizes, selectPreviewSize); MJPEG preferred
• UvcPreview widget keeps the camera's aspect ratio
• JPEG capture; a double-tap produces one image
• Hardware button: one event per press, releases and bounces filtered out
• status stream: previewing, paused, disconnected, closed
• Errors are HardwareExceptions from skio_core; opt-in logging via SkioLog

Android

• USB host (OTG) through UVCAndroid 1.0.13 (Apache-2.0) from Maven Central, called from Dart through JNI. Only three small Java classes exist: the texture/permission bridge, the preview texture's surface lifecycle, and JPEG encoding of a captured frame.
• Permissions: requestAccess(device) asks for CAMERA (required from Android 9 for USB video devices), then the USB grant for the device.
• The plugin declares only android.permission.CAMERA. It removes the extra permissions the UVC library declares (RECORD_AUDIO, storage, MANAGE_EXTERNAL_STORAGE, FOREGROUND_SERVICE) and marks USB host and camera hardware as optional, so Play Store reviews don't flag them.
• Captured JPEGs go to the app's cache directory; move or delete them.
• Cheap cameras often report only 1280x720 and 640x480 (MJPEG) plus YUYV sizes; use supportedSizes rather than assuming 1080p.

Web

• A UVC camera is an ordinary webcam in the browser, so this uses getUserMedia. Call requestAccess() from a user gesture; labels and ids stay hidden until the page has camera permission.
• Vendor and product IDs are read from Chrome's camera labels (Name (0c45:6366)), so DeviceFilter works there too.
• supportedSizes lists common sizes up to what the camera's track allows.
• Capture encodes the current video frame as JPEG and returns an in-memory XFile.
• The camera's hardware button is not available to web pages.

Testing your app without hardware

import 'package:skio_uvc_camera/platform_interface.dart';

UvcCameraPlatform.instance = MyFakePlatform(); // extends UvcCameraPlatform

The skio family

Package	Purpose
skio_core	Shared types: access status, errors, device filters, logging
skio_usb_serial	USB serial port
skio_uvc_camera	USB Video Class camera (this package)

Source and issues: github.com/skio-flutter/skio.