调用 session.setRepeatingRequest(captureRequestBuilder.build(), null, backgroundHandler) 时 Camera2 API 出错

Question

我正在尝试制作相机预览应用程序。当我打电话

session.setRepeatingRequest(captureRequestBuilder.build(), null, backgroundHandler)

我收到此错误：

E/HandlerDispatcher: IllegalArgumentException while invoking public abstract void android.hardware.camera2.CameraCaptureSession$StateCallback.onConfigured(android.hardware.camera2.CameraCaptureSession)
    java.lang.IllegalArgumentException: Each request must have at least one Surface target
        at android.hardware.camera2.impl.CameraDeviceImpl.submitCaptureRequest(CameraDeviceImpl.java:934)
        at android.hardware.camera2.impl.CameraDeviceImpl.setRepeatingRequest(CameraDeviceImpl.java:993)
        at android.hardware.camera2.impl.CameraCaptureSessionImpl.setRepeatingRequest(CameraCaptureSessionImpl.java:239)
        at anthe.rwca.org.robocup19.MainActivity$3.onConfigured(MainActivity.java:147)
        at java.lang.reflect.Method.invoke(Native Method)
        at android.hardware.camera2.dispatch.InvokeDispatcher.dispatch(InvokeDispatcher.java:39)
        at android.hardware.camera2.dispatch.HandlerDispatcher$1.run(HandlerDispatcher.java:65)
        at android.os.Handler.handleCallback(Handler.java:789)
        at android.os.Handler.dispatchMessage(Handler.java:98)
        at android.os.Looper.loop(Looper.java:164)
        at android.os.HandlerThread.run(HandlerThread.java:65)

这是我的代码：

CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {
        @Override
        public void onOpened(@NonNull CameraDevice camera) {
            cameraDevice = camera;
            createCaptureSession();
        }

        @Override
        public void onDisconnected(@NonNull CameraDevice camera) {

        }

        @Override
        public void onError(@NonNull CameraDevice camera, int error) {

        }
    };


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

        textureView = findViewById(R.id.textureView);
    }

    @Override
    protected void onResume() {
        super.onResume();
        textureView.setSurfaceTextureListener(new TextureView.SurfaceTextureListener() {
            @Override
            public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
                openBackgroundHandler();
                setupCamera();
                openCamera();
            }

            @Override
            public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {

            }

            @Override
            public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
                return false;
            }

            @Override
            public void onSurfaceTextureUpdated(SurfaceTexture surface) {

            }
        });
    }

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

    private void setupCamera() {
        cameraManager = (CameraManager) getSystemService(CAMERA_SERVICE);
        try {
            cameraIDs = cameraManager.getCameraIdList();
            cameraID = cameraIDs[0];
            Log.i(TAG, String.valueOf(cameraIDs.length));
            Log.i(TAG, cameraID);
            CameraCharacteristics cameraCharacteristics = cameraManager.getCameraCharacteristics(cameraID);
            StreamConfigurationMap streamConfigurationMap = cameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
            size = streamConfigurationMap.getOutputSizes(SurfaceTexture.class)[0];
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    @SuppressLint("MissingPermission")
    private void openCamera() {
        try {
            cameraManager.openCamera(cameraID, stateCallback, backgroundHandler);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    private void openBackgroundHandler() {
        handlerThread = new HandlerThread("camera_app");
        handlerThread.start();
        backgroundHandler = new Handler(handlerThread.getLooper());
    }

    private void closeBackgroundHandler() {
        handlerThread.quit();
        handlerThread = null;
        backgroundHandler = null;
    }

    private void createCaptureSession() {
        SurfaceTexture surfaceTexture = textureView.getSurfaceTexture();
        surfaceTexture.setDefaultBufferSize(size.getWidth(), size.getHeight());
        Surface surface = new Surface(surfaceTexture);
        try {
            cameraDevice.createCaptureSession(Collections.singletonList(surface), new CameraCaptureSession.StateCallback() {
                @Override
                public void onConfigured(@NonNull CameraCaptureSession session) {
                    try {
                        CaptureRequest.Builder captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
                        session.setRepeatingRequest(captureRequestBuilder.build(), null, backgroundHandler);

                    } catch (CameraAccessException e) {
                        e.printStackTrace();
                    }
                }

                @Override
                public void onConfigureFailed(@NonNull CameraCaptureSession session) {

                }
            }, backgroundHandler);
        } catch (CameraAccessException e1) {
            e1.printStackTrace();
        }
    }

我是 Camera2 API 的新手，所以我不知道错误意味着什么。我在互联网上环顾四周，但找不到类似的问题。

我还想知道如何在位图或 nv21 字节数组中获取预览帧，以便我可以对其进行一些图像处理并将处理后的图像显示为位图（或者有没有办法直接应用某些图像处理到预览帧）？先感谢您。

Answer 1

查看Camera2Basic示例以帮助了解一般流程。

在这种特殊情况下 - 一个捕获会话可以有多个目标输出表面（例如，一个用于预览，一个用于静态捕获 JPEG）。每个捕获请求可以针对这些输出的任何子集（因此重复请求针对预览输出，同时捕获针对 JPEG 输出等）。

因此，您的捕获请求需要将一个或多个 Surface 添加为目标，并且这些 Surface 必须是会话创建中包含的其中之一。

由于您的会话中只有一个 Surface，因此只需添加

 captureRequestBuilder.addTarget(surface)

在 setRepeatingRequest 调用之前。

如果您想获得 YUV 数据的 Java ByteBuffer，您也可以添加一个ImageReader作为输出目标，用于会话和捕获请求。请注意，仅保证支持 YUV_420_888 灵活的 YUV 格式，因此如果您确实需要 NV21 布局中的某些内容，则必须手动调整它（在任何给定设备上，YUV_420_888 可能是 NV21 引擎盖下的，但不能保证关于那个）。