婴儿监护系统中的音视频检测处理

Audio and Video Processing Technology in the Baby's Supervision System

婴儿监护系统的音视频监护部分主要要求实时的音视频图像显示、压缩、存储和异常情况的检测和报警.介绍了系统的音视频实时处理实现的主要技术,着重讨论了啼哭声音检测报警和婴儿纵向移动的异常情况报警方案,为防止婴儿在床上移动产生误报,提出两级视频图像运动检测的方法.

This paper introduces the system and construction of the baby's on_line supervision system. It presents an available displaying, coding and storing way of audio and video on_line supervision of many supervision points. The main techonology point addresses on the automatic alert detection based on baby's voice and abnormal motions. The proposed scheme suggests a new set of methods of video and audio detection and alert. In the baby's automatic supervision sytem, the baby's abnormal situations include crying and upright motions relative to the bed. General motion detection of video is performed on the change of the image and the object's movements in all directions. But to the baby's automatic supervision system, many movements are normal events and should not arouse the alert. To avoid unavailable alert as much as possible, the paper first analyses the characteristics of baby's crying voice and the movements in video. Then it suggests how to get the available value from the digital audio and video signals. The alert from the voice has been designed available only for the frequency in 1～20 kHz that includes the frequency region of baby's crying voice and filters the part of the normal speech. The lowest threshold volume of voice is 60 dD.In aspect of alert caused by video motions, only vertical motions to the bed are available signals. To detect baby's upright motions to bed, the paper proposes the video motion detection method based on two layers. Firstly, the system detects rapidly the video image's changes between two frames. The algorithm of different between two frames images be used to detect the frame image's change. When the image changes are detected, the system judges the motions' availability by the second algorithm. The second algorithm is expected to detect whether an image change is an available motion. It is based on the correlation between two frames. The camera is parallel to the bed. The correlation value is more sensitive to vertical motion than parallel motion. When the correlation value is set over 80,the parallel motion will mostly be ignored. It has been proved very useful to detect baby's abnormal motions.