onFaceDetection - flickery坐标

Question

我正确地检测到脸部，但我注意到即使检测到的脸部完全静止，边界框的坐标也会受到微小变化的影响。我想知道这是正常行为还是我做错了什么。我正在使用两个TextureView来显示相机预览和面部检测覆盖。VIDEO

我的代码示例：

public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {

    cameraTextureView.setSurfaceTextureListener(null);
    try {
        if (camera == null) {
            camera = Camera.open(CID);
        }


        //camera parameters init .... code ...code....

        camera.setPreviewCallback(new Camera.PreviewCallback() {
            public void onPreviewFrame(byte[] data, Camera camera) {
                final byte[] frame = data;           

                camera.setFaceDetectionListener(new Camera.FaceDetectionListener() {
                    @Override
                    public void onFaceDetection(Camera.Face[] faces, Camera c2) {

                        if (faces.length > 0) {
                            Face face = faces[0];

                            Canvas canvas = cameraOverlay.lockCanvas(null);
                            if (canvas == null) return;

                            canvas.drawColor(0, PorterDuff.Mode.CLEAR);

                            RectF bounds = new RectF(face.rect.left, face.rect.top, face.rect.right, face.rect.bottom);
                            canvas.drawRect(bounds, faceBoxPaint);

                                    /*START - convert driver coordinates to View coordinates in pixels*/
                            matrix.setScale(-1, 1); // for front facing camera (matrix.setScale(1, 1); otherwise)
                            matrix.postRotate(displayOrientation);
                            // Camera driver coordinates range from (-1000, -1000) to (1000, 1000).
                            // UI coordinates range from (0, 0) to (width, height).
                            matrix.postScale(cameraPrevWidthBox / 2000f, cameraPrevHeightBox / 2000f);
                            matrix.postTranslate(cameraPrevWidthBox / 2f, cameraPrevHeightBox / 2f);
                            matrix.mapRect(bounds);
                                    //END 

                            cameraOverlay.unlockCanvasAndPost(canvas);
                        }

                    }
                });
            }
        });
        camera.setPreviewTexture(surface);

        camera.startPreview();
        camera.startFaceDetection();

    } catch (Exception ioe) {
        // ~~
    }
}

我认为这可能与自动对焦或稳定功能有关，但显然情况并非如此。

我在带有Android 7.0的Samsung S7上运行我的代码。