OpenCV Android: Get camera frames in background without showing on the screen

Question

I have written an optic flow detection application which based on OpenCV for Android tutorials and source code of Barry Thomas's application OpenCV Demo 2. Now I want to make this application a background task so I can pass the detection result to my main activity via listener interface.

All the application samples in OpenCV totorials extends Activity and implements CvCameraViewListener and shows camera input on the scrren. I want to able to capture camera frames and do optic flow detection on frames in background without showing them on the screen.

How can I get frames from camera in background witout showing camera input?

score 1 · Answer 1 · answered May 24 '14 at 11:03

1

There are two ways, but you have to keep a Mat in the memory in the method onCameraFrame:

@Override
public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
    mRgba = inputFrame.rgba();      
    return mRgba;
}

1) make the cameraview invisible 2) make onCameraFrame return null

Both ways you should do your additional work in another view.

answered May 24 '14 at 11:03

xMKx

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Making the cameraview invisible stops any processing that happens per frame.. or at least this is what happens in my case – Mohamed Khamis Jun 26 '15 at 11:31
Making it invisible stops any processing. Returning null results in a black screen. – japedo Oct 26 '16 at 07:37

score 0 · Answer 2 · edited May 23 '17 at 12:25

0

The only way I found to get camera frames in background is by using a SurfaceTexture instead of a SurfaceView, and therefore set it using Camera.setPreviewTexture instead of Camera.setPreviewDisplay.

This answer as well as this one helped.

edited May 23 '17 at 12:25

Community

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1

answered Jun 16 '14 at 07:19

JonasVautherin

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You're talking about the Android Camera library, while the question is about OpenCV's library, which uses `org.opencv.android.CameraBridgeViewBase` – Mohamed Khamis Jun 26 '15 at 11:29

OpenCV Android: Get camera frames in background without showing on the screen

2 Answers2