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         }