java OpenCV 安卓 VideoWriter问题

Question

我在安卓中使用VideoWriter opencv类和JNI时遇到问题

我的目标是简单地捕获相机帧并使用VideoWriter将其写入文件

代码如下：

本机部分-3函数初始化编写器，编写框架并释放编写器

JNIEXPORT void JNICALL Java_com_driveassist_drivingassistant_WorkActivity_InitWriter(JNIEnv *env, jobject, jstring path)
{
    char const * new_path;
    new_path = env->GetStringUTFChars(path , NULL ) ;

    writer = VideoWriter();

    stringstream ss;
    ss << new_path;
    ss << "//1.mp4";

    string p;
    ss >> p;

    writer.open(p, CV_FOURCC('P', 'I', 'M', '1'), 24, Size(1024, 768));
}

JNIEXPORT void JNICALL Java_com_driveassist_drivingassistant_WorkActivity_WriteFrame(JNIEnv *, jobject, jlong frame)
{
    Mat* im=(Mat*)frame;
    Mat im_p = (*im).clone();

    if(writer.isOpened())
    {
        resize(im_p, im_p, Size(1024, 768), 0, 0, INTER_AREA);

        writer.write(im_p);
    }

}

JNIEXPORT void JNICALL Java_com_driveassist_drivingassistant_WorkActivity_ReleaseWriter(JNIEnv *, jobject)
{
    if(writer.isOpened())
    {
        writer.release();
    }
}

Java部分：

我使用带有opencv CameraBridgeViewBase的活动：

public class WorkActivity extends Activity implements CvCameraViewListener {

    private CameraBridgeViewBase   mOpenCvCameraView;

    private Mat mRgba;

    private File mediaStorageDir;

    private BaseLoaderCallback     mLoaderCallback = new BaseLoaderCallback(this) {
        @Override
        public void onManagerConnected(int status) {
            switch (status) {
                case LoaderCallbackInterface.SUCCESS:
                {
                    System.loadLibrary("driving_assistant");

                    mOpenCvCameraView.enableView();

                    InitWriter(mediaStorageDir.getPath());
                } break;
                default:
                {
                    super.onManagerConnected(status);
                } break;
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

        setContentView(R.layout.activity_work);

        mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "DriveAssistantCam");

        if (! mediaStorageDir.exists()){
            if (! mediaStorageDir.mkdirs()){
                Log.d("DrivingAssistant", "failed to create directory");
            }
        }

        mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.work_camera_surface_view);

        mOpenCvCameraView.setCvCameraViewListener(this);
    }

    @Override
    public void onPause()
    {
        if (mOpenCvCameraView != null)
            mOpenCvCameraView.disableView();

        super.onPause();

        // ReleaseWriter();
    }

    @Override
    public void onResume()
    {
        super.onResume();

        OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_3, this, mLoaderCallback);

        // OpenCVLoader.initDebug();
    }

    public void onDestroy() {
        super.onDestroy();

        if (mOpenCvCameraView != null)
            mOpenCvCameraView.disableView();

        ReleaseWriter();
    }

    public void onCameraViewStarted(int width, int height) {
        mRgba = new Mat(height, width, CvType.CV_8UC4);
    }

    public void onCameraViewStopped() {
        mRgba.release();

        ReleaseWriter();
    }

    public Mat onCameraFrame(Mat inputFrame) {
        inputFrame.copyTo(mRgba);

        WriteFrame(mRgba.getNativeObjAddr());

        return mRgba;
    }

代码运行时没有异常，但视频文件不会出现。本机库正常加载，并且应用程序可以访问该目录（我尝试在那里用java.io.file创建一个文件）

我的系统是Ubuntu12.10，EclipseIndigo。我在emulator和galaxy tab 2上试过这段代码

非常感谢

Answer 1

嗯，回答我自己的问题已经成为一个好传统：）

OpenCV for adnroid尚不支持视频读写。我在谷歌集团“Opencv4Android”中发现了这一点：

Andrey Pavlenko andrey.pavlenko@itseez.com через googlegroups.com 4 янв. (5 дн. назад)

кому: android-opencv Unfortunately on Android OpenCV doesn't support yet video reading and writing even in the later version 2.4.3.2. Hope it will be enabled in the next release...

可能我必须使用ffmpeg或其他库