android Camera 录像时旋转角度

录像保存时，旋转角度要与所拍录像时的角度保持一致，否则，看起来就会出现角度不度，巅倒等问题。

一般在开始录像之前会先去初始化录像

initializeRecorder 中会去读取当前的录像或拍照的旋转角度，并跟据当前的角度来选择一个角度写到所拍

照片或者视频的 exif 信息中去。

 1 // See android.hardware.Camera.Parameters.setRotation for   2         // documentation.   3         // Note that mOrientation here is the device orientation, which is the opposite of   4         // what activity.getWindowManager().getDefaultDisplay().getRotation() would return,   5         // which is the orientation the graphics need to rotate in order to render correctly.   6         int rotation = 0;   7         if (mOrientation != OrientationEventListener.ORIENTATION_UNKNOWN) {   8             CameraInfo info = CameraHolder.instance().getCameraInfo()[mCameraId];   9             if (info.facing == CameraInfo.CAMERA_FACING_FRONT) {  10                 rotation = (info.orientation - mOrientation + 360) % 360;  11             } else {  // back-facing camera  12                 rotation = (info.orientation + mOrientation) % 360;  13             }  14         } else {  15             //Get the right original orientation  16             CameraInfo info = CameraHolder.instance().getCameraInfo()[mCameraId];  17             rotation = info.orientation;  18         }  19 //        mMediaRecorder.setOrientationHint(rotation);  20   21         if (mCameraId == CameraInfo.CAMERA_FACING_FRONT) {  22             if (rotation == 270 || rotation == 90 || rotation == 180) {  23                 mMediaRecorder.setOrientationHint(180);  24             } else {  25                 mMediaRecorder.setOrientationHint(0);  26             }  27         } else {  28             if (rotation == 180){  29                 mMediaRecorder.setOrientationHint(180);  30             }else{  31                 mMediaRecorder.setOrientationHint(0);  32             }  33         }