manipulate JavaCamera2View to set Parameters for Camera Device - OpenCV in Android - opencv

Question

Software: Android 4.1.1, OpenCV 4.5.0
To briefly summarize my project. i want to continuously monitor the 'frequency' of a flickering led light source using the rolling shutter effect based on a cmos camera of an android smartphone. in the video/'image stream' a light dark stripe pattern should be visible, which i want to analize with opencv.
if you are interested in the method, you can find more information here:
RollingLight: Light-to-Camera Communications
now the actual problem: i need to set the camera parameters to fixed values before i start analizing with opencv. the exposure time should be as short as possible, the iso (sensitivity) should get a medium value and the focus should be set as close as possible.
for this i made the following changes (marked as comments //) in the methods initializeCamera() and createCameraPreviewSession() from the opencv's JavaCamera2View.java file.
initializeCamera() - from JavaCamera2View.java
public int minExposure = 0;
public int maxExposure = 0;
public long valueExposure = minExposure;
public float valueFocus = 0;
public int minIso = 0;
public int maxIso = 0;
public int valueIso = minIso;
public long valueFrameDuration = 0;
protected boolean initializeCamera() {
Log.i(LOGTAG, "initializeCamera");
CameraManager manager = (CameraManager) getContext().getSystemService(Context.CAMERA_SERVICE);
try {
String camList[] = manager.getCameraIdList();
if (camList.length == 0) {
Log.e(LOGTAG, "Error: camera isn't detected.");
return false;
}
if (mCameraIndex == CameraBridgeViewBase.CAMERA_ID_ANY) {
mCameraID = camList[0];
} else {
for (String cameraID : camList) {
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraID);
if ((mCameraIndex == CameraBridgeViewBase.CAMERA_ID_BACK &&
characteristics.get(CameraCharacteristics.LENS_FACING) == CameraCharacteristics.LENS_FACING_BACK) ||
(mCameraIndex == CameraBridgeViewBase.CAMERA_ID_FRONT &&
characteristics.get(CameraCharacteristics.LENS_FACING) == CameraCharacteristics.LENS_FACING_FRONT)
) {
mCameraID = cameraID;
break;
}
}
}
if (mCameraID != null) {
Log.i(LOGTAG, "Opening camera: " + mCameraID);
//I added this code to get the parameters---------------------------------------------------------------------------
CameraManager mCameraManager = (CameraManager) getContext().getSystemService(Context.CAMERA_SERVICE);
try {
CameraCharacteristics mCameraCharacteristics = mCameraManager.getCameraCharacteristics(mCameraID);
valueFocus = mCameraCharacteristics.get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);
Range<Integer> rangeExposure = mCameraCharacteristics.get(CameraCharacteristics.CONTROL_AE_COMPENSATION_RANGE);
minExposure = rangeExposure.getLower();
maxExposure = rangeExposure.getUpper();
Range<Integer> rangeIso = mCameraCharacteristics.get(CameraCharacteristics.SENSOR_INFO_SENSITIVITY_RANGE);
minIso = rangeIso.getLower();
maxIso = rangeIso.getUpper();
valueFrameDuration = mCameraCharacteristics.get(CameraCharacteristics.SENSOR_INFO_MAX_FRAME_DURATION);
} catch (CameraAccessException e) {
Log.e(LOGTAG, "calcPreviewSize - Camera Access Exception", e);
} catch (IllegalArgumentException e) {
Log.e(LOGTAG, "calcPreviewSize - Illegal Argument Exception", e);
} catch (SecurityException e) {
Log.e(LOGTAG, "calcPreviewSize - Security Exception", e);
}
//end of code-------------------------------------------------------------------------------------------------------
manager.openCamera(mCameraID, mStateCallback, mBackgroundHandler);
} else { // make JavaCamera2View behaves in the same way as JavaCameraView
Log.i(LOGTAG, "Trying to open camera with the value (" + mCameraIndex + ")");
if (mCameraIndex < camList.length) {
mCameraID = camList[mCameraIndex];
manager.openCamera(mCameraID, mStateCallback, mBackgroundHandler);
} else {
// CAMERA_DISCONNECTED is used when the camera id is no longer valid
throw new CameraAccessException(CameraAccessException.CAMERA_DISCONNECTED);
}
}
return true;
} catch (CameraAccessException e) {
Log.e(LOGTAG, "OpenCamera - Camera Access Exception", e);
} catch (IllegalArgumentException e) {
Log.e(LOGTAG, "OpenCamera - Illegal Argument Exception", e);
} catch (SecurityException e) {
Log.e(LOGTAG, "OpenCamera - Security Exception", e);
}
return false;
}
createCameraPreviewSession() - from JavaCamera2View.java
private void createCameraPreviewSession() {
final int w = mPreviewSize.getWidth(), h = mPreviewSize.getHeight();
Log.i(LOGTAG, "createCameraPreviewSession(" + w + "x" + h + ")");
if (w < 0 || h < 0)
return;
try {
if (null == mCameraDevice) {
Log.e(LOGTAG, "createCameraPreviewSession: camera isn't opened");
return;
}
if (null != mCaptureSession) {
Log.e(LOGTAG, "createCameraPreviewSession: mCaptureSession is already started");
return;
}
mImageReader = ImageReader.newInstance(w, h, mPreviewFormat, 2);
mImageReader.setOnImageAvailableListener(new ImageReader.OnImageAvailableListener() {
#Override
public void onImageAvailable(ImageReader reader) {
Image image = reader.acquireLatestImage();
if (image == null)
return;
// sanity checks - 3 planes
Image.Plane[] planes = image.getPlanes();
assert (planes.length == 3);
assert (image.getFormat() == mPreviewFormat);
JavaCamera2Frame tempFrame = new JavaCamera2Frame(image);
deliverAndDrawFrame(tempFrame);
tempFrame.release();
image.close();
}
}, mBackgroundHandler);
Surface surface = mImageReader.getSurface();
mPreviewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_MANUAL);
mPreviewRequestBuilder.addTarget(surface);
mCameraDevice.createCaptureSession(Arrays.asList(surface),
new CameraCaptureSession.StateCallback() {
#Override
public void onConfigured(CameraCaptureSession cameraCaptureSession) {
Log.i(LOGTAG, "createCaptureSession::onConfigured");
if (null == mCameraDevice) {
return; // camera is already closed
}
mCaptureSession = cameraCaptureSession;
try {
//I added this code to set the parameters---------------------------------------------------------------------------
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_OFF);
mPreviewRequestBuilder.set(CaptureRequest.LENS_FOCUS_DISTANCE, valueFocus);
mPreviewRequestBuilder.set(CaptureRequest.SENSOR_EXPOSURE_TIME, valueExposure);
mPreviewRequestBuilder.set(CaptureRequest.SENSOR_SENSITIVITY, valueIso);
mPreviewRequestBuilder.set(CaptureRequest.SENSOR_FRAME_DURATION, valueFrameDuration);
//end of code-------------------------------------------------------------------------------------------------------
mCaptureSession.setRepeatingRequest(mPreviewRequestBuilder.build(), null, mBackgroundHandler);
Log.i(LOGTAG, "CameraPreviewSession has been started");
} catch (Exception e) {
Log.e(LOGTAG, "createCaptureSession failed", e);
}
}
#Override
public void onConfigureFailed(CameraCaptureSession cameraCaptureSession) {
Log.e(LOGTAG, "createCameraPreviewSession failed");
}
},
null
);
} catch (CameraAccessException e) {
Log.e(LOGTAG, "createCameraPreviewSession", e);
}
}
unfortunately, the above editing does not work. console shows:
java.lang.NullPointerException: Attempt to invoke virtual method 'float java.lang.Float.floatValue()' on a null object reference
maybe not the only problem i guess.
i have already read numerous posts about the interaction between opencv and androids camera 2 (camerax) api. regarding my question, however, this post unfortunately sums it up: "OpenCV will not work with android.camera2" but, the post is a few years old and i hope there is a workaround for the problem by now.
1.) do you know how i can set fix camera parameters and then do an analysis in opencv? could you explain the steps to me?
2.) are there any existing available projects as reference?
3.) i need the highest possible frame rate of the camera. otherwise i would have thought that i could work with getbitmap(); and forward the image to opencv. but the frame rate is really bad and besides i'm not sure here either how to set the camera parameters fix before taking the photo. or do you know any alternatives?
thanks in advance for your support. if you need more info, i will be happy to share it with you.
--
2021 arpil: the questions are still unanswered. if someone doesn't answer them in detail but has links that could help me, i would really appreciate it.