如何使用Camera2 API获取框架

Question

I am using camera2 api to get the camera frames and this is the code I have written

private void startPreview() {
    SurfaceTexture surfaceTexture = mTextureView.getSurfaceTexture();
    surfaceTexture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
    Surface previewSurface = new Surface(surfaceTexture);

    try {
        mCaptureRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        mCaptureRequestBuilder.addTarget(previewSurface);

        mCameraDevice.createCaptureSession(Arrays.asList(previewSurface),
                new CameraCaptureSession.StateCallback() {
                    @Override
                    public void onConfigured(@NonNull CameraCaptureSession session) {
                        try {
                            session.setRepeatingRequest(mCaptureRequestBuilder.build(),
                                    new CameraCaptureSession.CaptureCallback() {

                                        @Override
                                        public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
                                            super.onCaptureCompleted(session, request, result);
                                            Log.i("State preview", "process: frame");

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

                    @Override
                    public void onConfigureFailed(@NonNull CameraCaptureSession session) {
                        Toast.makeText(getApplicationContext(),
                                "Unable to setup camera preview", Toast.LENGTH_SHORT).show();
                    }
                }, null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }

}

I am able to see the frame log through this line:

session.setRepeatingRequest(mCaptureRequestBuilder.build(),
                                    new CameraCaptureSession.CaptureCallback() {

                                        @Override
                                        public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
                                            super.onCaptureCompleted(session, request, result);
                                            Log.i("State preview", "process: frame");

                                        }
                                    }, mBackgoundThreadHandler);

So from this function how do I get the frame. I am totally new to camera2 api so could someone please help me.

Answer 1

Your code just currently drawing camera preview to your TextureView; if you want a second output that your application code can read, you need to create a second output and give it to camera.

Depending on what kind of processing you want to do, you want either a ImageReader for Java-level access, a SurfaceTexture (for reading in OpenGL), or a Allocation (for RenderScript). From each of these, you can get a Surface to include in the session creation and in creating the capture request.

Each of them has a callback that fires when new frames become available. onCaptureCompleted only provides the capture metadata.