OpenCV 应用程序 - Android 相机在 10 秒后崩溃

Question

背景

在此应用程序中，我能够启动在 Android Studio 中开发的相机预览，目的是将 OpenCV 纳入其中。但是，我遇到了一个错误；相机预览只持续大约 10 秒，直到它崩溃并且应用程序关闭。有什么办法可以解决这个问题吗？这是我的代码；

MainActivity.java

package com.example.cv;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.Manifest;
import android.content.pm.PackageManager;
import android.opengl.Matrix;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceView;
import android.widget.Toast;

import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.JavaCameraView;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.imgproc.Imgproc;

public class MainActivity extends AppCompatActivity implements CameraBridgeViewBase.CvCameraViewListener2
{
    private static String TAG = "MainActivity";
    JavaCameraView javaCameraView;
    Mat mRGBA, mRGBAT;

    private static final int MY_CAMERA_REQUEST_CODE = 100;


    BaseLoaderCallback baseLoaderCallback = new BaseLoaderCallback(MainActivity.this) {
        @Override
        public void onManagerConnected(int status)
        {
            if (status == BaseLoaderCallback.SUCCESS) {
                javaCameraView.enableView();
            } else {
                super.onManagerConnected(status);
            }
        }
    };

    static
    {
        if (OpenCVLoader.initDebug())
        {
            Log.d(TAG, "OpenCV is Configured or Connected successfully.");
        }
        else
        {
            Log.d(TAG, "OpenCV not Working or Loaded.");
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        javaCameraView = (JavaCameraView) findViewById(R.id.my_camera_view);


        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
                == PackageManager.PERMISSION_GRANTED)  {
            Log.d(TAG, "Permissions granted");
            javaCameraView.setCameraPermissionGranted();
            javaCameraView.setCameraIndex(CameraBridgeViewBase.CAMERA_ID_BACK);
            javaCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
            javaCameraView.setCvCameraViewListener(this);
        } else {
            Log.d(TAG, "Permission prompt");
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, MY_CAMERA_REQUEST_CODE);
        }

    }

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

    @Override
    public void onCameraViewStopped()
    {
        mRGBA.release();
    }

    @Override
    public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame)
    {
        mRGBA = inputFrame.rgba();
        mRGBAT = mRGBA.t();
        Core.flip(mRGBA.t(), mRGBAT, 1);
        Imgproc.resize(mRGBAT, mRGBAT, mRGBA.size());
        return mRGBAT;
    }

    @Override
    public void onPointerCaptureChanged(boolean hasCapture) {

    }


    @Override
    protected void onDestroy() {
        super.onDestroy();

        if (javaCameraView != null)
        {
            javaCameraView.disableView();
        }
    }

    @Override
    protected void onPause() {
        super.onPause();

        if (javaCameraView != null)
        {
            javaCameraView.disableView();
        }
    }


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

        if (OpenCVLoader.initDebug())
        {
            Log.d(TAG, "OpenCV is Configured or Connected successfully.");
            baseLoaderCallback.onManagerConnected(BaseLoaderCallback.SUCCESS);
        }
        else
        {
            Log.d(TAG, "OpenCV not Working or Loaded.");
            OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION, this, baseLoaderCallback);
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == MY_CAMERA_REQUEST_CODE) {
            // camera can be turned on
            Toast.makeText(this, "camera permission granted", Toast.LENGTH_LONG).show();
            javaCameraView.setCameraPermissionGranted();
            javaCameraView.setCameraIndex(CameraBridgeViewBase.CAMERA_ID_FRONT);
            javaCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
            javaCameraView.setCvCameraViewListener(this);
        } else {
            //camera will stay off
            Toast.makeText(this, "camera permission denied", Toast.LENGTH_LONG).show();
        }
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.cv">


    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-feature android:name="android.hardware.camera"/>
    <uses-feature android:name="android.hardware.camera.autofocus"/>
    <uses-feature android:name="android.hardware.camera.front"/>
    <uses-feature android:name="android.hardware.camera.front.autofocus"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <org.opencv.android.JavaCameraView
        android:id="@+id/my_camera_view"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        />

</RelativeLayout>

Answer 1

再见，

我对您的问题做了进一步调查，这里有一些注意事项：

1 - 我已经在 to release the matrices inside onCameraFrame() as soon as they are not needed anymore. Forgetting this can generate garbage collection issues, as outlined or here 的评论中建议过你了。您可以使用 Mat.release() 方法显式调用此过程，就像用户在同一答案中所做的那样。你试过了吗？从我的测试来看，它延长了 10 秒的相机寿命，尽管尚未修复错误
2 - 从相反，我们可以理解转置太多次可能会造成其他麻烦。让我们看看您的代码：

mRGBAT = mRGBA.t();
Core.flip(mRGBA.t(), mRGBAT, 1);

这看起来确实是我们可以改进的地方。您首先将 mRGBA.t() 分配给 mRGBAT，然后在调用 Core.flip() 时再次要求计算 mRGBA 的转置矩阵。结果已经存储在mRGBAT中，不需要再进行这样的操作。然后你可以这样解决这个问题：

mRGBAT = mRGBA.t();
Core.flip(mRGBAT, mRGBAT, 1);

3 - 在 Mat.t() 和 Core.transpose() 之间，但第一个是第二个的包装器，我们可以直接使用后者

解决您问题的完整代码段如下：

Mat mRGBA, mRGBAT, dst;

@Override
public void onCameraViewStarted(int width, int height)
{
    mRGBAT = new Mat();
    dst = new Mat();
}

@Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame)
{
    mRGBA = inputFrame.rgba();
    Core.transpose(mRGBA, mRGBAT);
    Core.flip(mRGBAT, mRGBAT, 1);
    Imgproc.resize(mRGBAT, dst, mRGBA.size());
    mRGBA.release();
    mRGBAT.release();
    return dst;
}

周末愉快，
安东尼奥

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