Android平台GB28181设备接入模块分辨率发生变化怎么办？

技术背景

我们在做Android平台gb28181设备接入模块的时候，遇到这样的情况，比如横竖屏分辨率不锁定，采集摄像头的时候，可以实现，横屏状态采集横屏，竖屏状态采集竖屏，简单来说，横屏状态比如采集的1280*720的，竖屏状态，采集的数据源成了720*1280。

这块对我们来说，已经轻车熟路了，老早就已经处理，分辨率发生变化的时候，会重启encoder，确保正常兼容，不幸的是，好多gb28181平台侧，对分辨率切换，支持的并不友好，分辨率发生变化的时候，有些国标平台播放上来的视频流的时候，会直接crash。

分辨率变化，其实多数国标平台厂商都可以兼容，或者说应该兼容，如果国标平台侧不兼容的话，我们可以在android平台gb28181设备接入侧做一定的处理。

技术实现

以Android的camera2为例，我们做了“锁定图像方向”选项：

对应的代码实现如下：

    class ButtonCameraImageOrientationLockListener implements View.OnClickListener {public void onClick(View v) {is_need_lock_image_orientation_ = !is_need_lock_image_orientation_;if (cur_image_orientation_ >= 0)cur_image_orientation_ = orientation_;if(camera2Helper != null)cameraImageRotationDegree_ = camera2Helper.getCameraImageRotationDegree(cur_image_orientation_ < 0 ?orientation_ : cur_image_orientation_);btnCameraImageOrientationLock.setText(is_need_lock_image_orientation_?"解锁图像方向" : "锁定图像方向");}}

其中，getCameraImageRotationDegree实现如下：

    public int getCameraImageRotationDegree(int device_degree) {if (device_degree < 0)return -1;String camera_id = getCameraId();int degree;if (CAMERA_ID_BACK.equals(camera_id)) {degree = (mSensorOrientation + device_degree + 360) % 360;Log.i(TAG, "getCameraImageRotationDegree BACK device_degree:" + device_degree+ " SENSOR_ORIENTATION:" + mSensorOrientation + " degree:" + degree);}else {degree = (mSensorOrientation - device_degree + 360) % 360;Log.i(TAG, "getCameraImageRotationDegree FRONT device_degree:" + device_degree+ " SENSOR_ORIENTATION:" + mSensorOrientation + " degree:" + degree);}return degree;}

针对摄像头rotation变化监测listener：

 /** Github: https://github.com/daniulive/SmarterStreaming   */class OnOriChangedListener implements OrientationDetector.OriginListener {@Overridepublic void onOrientationChanged(int orientation, int rotation) {orientation_ = orientation;if (!is_need_lock_image_orientation_ || cur_image_orientation_ < 0)cur_image_orientation_ = orientation_;Log.i(TAG, "onOrientationChanged:" + orientation + " rotation:" + rotation + " rotation.toString:" + Camera2Helper.getRotationString(rotation));if(camera2Helper != null) {camera2Helper.updateOrientation(orientation);cameraImageRotationDegree_ = camera2Helper.getCameraImageRotationDegree(cur_image_orientation_ < 0 ?orientation_ : cur_image_orientation_);}if (layer_post_thread_ != null ) {int rotation_degree = cameraImageRotationDegree_;if (rotation_degree < 0)layer_post_thread_.updateVideoSize(0, 0);else if (90 == rotation_degree || 270 == rotation_degree)layer_post_thread_.updateVideoSize(video_height_, video_width_);elselayer_post_thread_.updateVideoSize(video_width_, video_height_);}}}