double record_motion_rate; /**< motion rate of video recording for slow/fast motion recording */
GstClockTime prev_preview_ts; /**< previous preview frame timestamp */
GstClockTime base_video_ts; /**< base video frame timestamp */
+ GstClockTime last_video_ts; /**< last video timestamp which is not modified */
guint record_drop_count; /**< drop count of video recording for slow/fast motion recording */
guint64 video_frame_count; /**< current video frame */
guint64 audio_frame_count; /**< current audio frame */