Android相机2 API剪裁视频

Question

我正在尝试使用Android Camera2 API录制视频。我试图通过在请求构建器中设置SCALER_CROP_REGION来将视频裁剪为正方形。我使用了以下代码，但似乎无效。

mCameraDevice.createCaptureSession(surfaces, new CameraCaptureSession.StateCallback() {

    @Override
    public void onConfigured( CameraCaptureSession cameraCaptureSession) {
        mCaptureSession = cameraCaptureSession;
        try {
            mIsRecording = true;

            /////****** this where i'm setting the coping 
            mZoom = getZoomRect();
            mPreviewRequestBuilder.set(CaptureRequest.SCALER_CROP_REGION, mZoom);
            /////////******************
            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
            HandlerThread thread = new HandlerThread("CameraPreview");
            thread.start();
            mCaptureSession.setRepeatingRequest(mPreviewRequestBuilder.build(), null, mBackgroundHandler);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onConfigureFailed( CameraCaptureSession cameraCaptureSession) {
        Log.d(TAG, "onConfigureFailed");
    }}, mBackgroundHandler);

这是应该获取裁剪区域的代码

public int zoom_level = 1;
public Rect mZoom = null;

public Rect getZoomRect(){
    try {
        CameraManager manager = (CameraManager) getApplicationContext().getSystemService(Context.CAMERA_SERVICE);
        CameraCharacteristics characteristics = manager.getCameraCharacteristics(mCameraId);
        float maxzoom = (characteristics.get(CameraCharacteristics.SCALER_AVAILABLE_MAX_DIGITAL_ZOOM))*10;
        Rect m = characteristics.get(CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE);

        int minW = (int) (m.width() / maxzoom);
        int minH = (int) (m.height() / maxzoom);
        int difW = m.width() - minW;
        int difH = m.height() - minH;
        int cropW = difW /100 *(int)zoom_level;
        int cropH = difH /100 *(int)zoom_level;
        cropW -= cropW & 3;
        cropH -= cropH & 3;
        mZoom = new Rect(cropW, cropH, m.width() - cropW, m.height() - cropH);
        ///// if recording video make it square 
        if (mIsRecording) {
            mZoom = new Rect(cropW, cropH, m.width() - cropW, m.width() - cropW);
        }


    } catch (CameraAccessException e) {
        Log.e(TAG, "can not access camera",e);
        throw new RuntimeException("can not access camera.", e);
    } catch (NullPointerException ex) {
        Log.e(TAG, "touch logic",ex);
    }

    return mZoom;
}

- man-r

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问题到底是什么？ - Al Lelopath

设置SCALER_CROP_REGION不会改变生成视频的任何内容。 - man-r

Answer 1

假设缩放级别为1，且SCALER_AVAILABLE_MAX_DIGITAL_ZOOM为4，则最终结果为：

minW = m.width/40
minH = m.height/40
difW = m.width*39/40
difH = m.height*39/40
cropW = m.width*39/40/100 * 1
cropH = m.height*39/40/100 * 1
(floor cropW/cropH down to nearest multiple of 4)

如果 m.width = 3000，m.width=2000，则 cropW = 28，cropH = 16。

因此，录制的 mZoom 为

Rect(28, 16, 2972, 2972).

这并不是居中显示，很多设备只支持居中缩放。但至少它是一个正方形的区域。

真正的问题是，你无法通过裁剪来改变输出的纵横比 - 当你创建一个捕捉会话时，输出Surface的纵横比由分辨率固定。请参阅这些图表了解裁剪的工作原理。

- Eddy Talvala

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什么是 m.width = 3000，m.width = 2000？感到困惑。 - Rohit Patil