OpenCV 应用程序 - Android 相机在 10 秒后崩溃

Question

背景

在这个应用程序中，我能够启动在 Android Studio 中开发的相机预览，旨在将 OpenCV 整合到其中。但是，我面临一个错误；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

喏，

我对您的问题进行了进一步调查，以下是一些注意事项：

1 - 我已经在 this previous answer 的 cmets 中建议您在不再需要它们时立即释放 onCameraFrame() 中的矩阵。如in this answer 或here 所述，忘记这一点可能会产生垃圾收集问题。您可以使用 Mat.release() 方法显式调用此过程以发生，就像用户在相同的答案中所做的那样。你试过了吗？根据我的测试，它延长了 10 秒的相机寿命，尽管尚未修复错误
2 - 取而代之的是this answer，我们可以理解转置太多次可能会产生其他麻烦。让我们看看你的代码：

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

这绝对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，因此无需再次执行该操作。然后你可以像这样解决这个问题：

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

3 - Mat.t() 和 Core.transpose() 之间的 there is no real difference 但第一个是第二个的包装器，我们可以直接使用后者

将解决您的问题的整个 sn-p 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，
安东尼诺