So as to retrieve audio-visual materials and obtain information. According to the information about books and audio-visual materials, the purpose of establishing books and audio-visual materials is to facilitate the retrieval of audio-visual materials and the acquisition of information. It is also organized into a detailed description library with a retrieval entrance, which is convenient for the retrieval of audio-visual materials and the acquisition of information. Public libraries record audio-visual materials based on MARC format and metadata based on DC.