If the pre-recording function is turned on and the pre-recording time is 30s, the video will start to be recorded after the power is turned on. After the time is more than 30 seconds, it will continue to record and continuously cover the video 30 seconds ago. When the video button is pressed, it will be pressed The first 30 seconds are also recorded in the recorded video. The Post recording function is to continue recording for 30 seconds after pressing the stop recording button.