Estoy usando un servicio que se inicia cuando arranca el dispositivo Android. Esto es porque no necesito una actividad visible. Funciona bien hasta ahora. Pero ahora estoy tratando de abrir la cámara (en MyService.onStart) y hacer un procesamiento básico de imágenes. Comprendí que la clase de cámara de Android predeterminada necesita una superficie para la vista previa de video. Por eso quiero usar VideoCapture de OpenCV.

Pero me sale este error:

No se encontró ninguna implementación para Lorg / opencv / highgui / VideoCapture nativo; .n_VideoCapture: (I) J

Me pregunto si esto es porque no tengo la siguiente línea como se usa en los ejemplos de OpenCV que usan una Actividad principal. La pregunta es, cómo integrar esto en mi servicio y cuándo inicializar el miembro de VideoCapture.

OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_5, this, mLoaderCallback);

Aquí está mi código hasta ahora. La mayoría del código de OpenCV se toma de NativeCameraView y CameraBridgeViewBase de OpenCV

package com.example.boot;

import org.opencv.android.Utils;
import org.opencv.core.Mat;
import org.opencv.core.Size;
import org.opencv.highgui.Highgui;
import org.opencv.highgui.VideoCapture;

import android.app.Service;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;

public final class MyService extends Service
{
    private static final String TAG = "MyService";
    private boolean mStopThread;
    private Thread mThread;
    private VideoCapture mCamera;
    private int mFrameWidth;
    private int mFrameHeight;
    private int mCameraIndex = -1;
    private Bitmap mCacheBitmap;

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    public void onDestroy() {

        this.disconnectCamera();

        Toast.makeText(this, "service stopped", Toast.LENGTH_LONG).show();
        Log.d(TAG, "onDestroy");
    }

    @Override
    public void onStart(Intent intent, int startid)
    {           
        Log.d(TAG, "service.onStart: begin");

        try
        {
            if (!connectCamera(640, 480))
                Log.e(TAG, "Could not connect camera");
            else
                Log.d(TAG, "Camera successfully connected");
        }
        catch(Exception e)
        {
            Log.e(TAG, "MyServer.connectCamera throws an exception: " + e.getMessage());
        }

        Toast.makeText(this, "service started", Toast.LENGTH_LONG).show();
        Log.d(TAG, "service.onStart: end");
    }

    private boolean connectCamera(int width, int height) {
        /* First step - initialize camera connection */
        if (!initializeCamera(width, height))
            return false;

        /* now we can start update thread */
        mThread = new Thread(new CameraWorker());
        mThread.start();

        return true;
    }

    private boolean initializeCamera(int width, int height) {
        synchronized (this) {

            if (mCameraIndex == -1)
                mCamera = new VideoCapture(Highgui.CV_CAP_ANDROID);
            else
                mCamera = new VideoCapture(Highgui.CV_CAP_ANDROID + mCameraIndex);

            if (mCamera == null)
                return false;

            if (mCamera.isOpened() == false)
                return false;

            //java.util.List<Size> sizes = mCamera.getSupportedPreviewSizes();

            /* Select the size that fits surface considering maximum size allowed */
            Size frameSize = new Size(width, height);

            mFrameWidth = (int)frameSize.width;
            mFrameHeight = (int)frameSize.height;

            AllocateCache();

            mCamera.set(Highgui.CV_CAP_PROP_FRAME_WIDTH, frameSize.width);
            mCamera.set(Highgui.CV_CAP_PROP_FRAME_HEIGHT, frameSize.height);
        }

        Log.i(TAG, "Selected camera frame size = (" + mFrameWidth + ", " + mFrameHeight + ")");

        return true;
    }

    protected void AllocateCache()
    {
        mCacheBitmap = Bitmap.createBitmap(mFrameWidth, mFrameHeight, Bitmap.Config.ARGB_8888);
    }

    private void releaseCamera() {
        synchronized (this) {
            if (mCamera != null) {
                mCamera.release();
            }
        }
    }

    private void disconnectCamera() {
        /* 1. We need to stop thread which updating the frames
         * 2. Stop camera and release it
         */
        try {
            mStopThread = true;
            mThread.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            mThread =  null;
            mStopThread = false;
        }

        /* Now release camera */
        releaseCamera();
    }

    protected void deliverAndDrawFrame(NativeCameraFrame frame) 
    {
        Mat modified = frame.rgba();

        boolean bmpValid = true;
        if (modified != null) {
            try {
                Utils.matToBitmap(modified, mCacheBitmap);
            } catch(Exception e) {
                Log.e(TAG, "Mat type: " + modified);
                Log.e(TAG, "Bitmap type: " + mCacheBitmap.getWidth() + "*" + mCacheBitmap.getHeight());
                Log.e(TAG, "Utils.matToBitmap() throws an exception: " + e.getMessage());
                bmpValid = false;
            }
        }
    }    

    private class NativeCameraFrame 
    {
        public Mat rgba() {
            mCapture.retrieve(mRgba, Highgui.CV_CAP_ANDROID_COLOR_FRAME_RGBA);
            return mRgba;
        }

        public Mat gray() {
            mCapture.retrieve(mGray, Highgui.CV_CAP_ANDROID_GREY_FRAME);
            return mGray;
        }

        public NativeCameraFrame(VideoCapture capture) {
            mCapture = capture;
            mGray = new Mat();
            mRgba = new Mat();
        }

        private VideoCapture mCapture;
        private Mat mRgba;
        private Mat mGray;
    };

    private class CameraWorker implements Runnable 
    {
        public void run() 
        {
            do 
            {
                if (!mCamera.grab()) {
                    Log.e(TAG, "Camera frame grab failed");
                    break;
                }

                deliverAndDrawFrame(new NativeCameraFrame(mCamera));

            } while (!mStopThread);
        }
    }
}