University textbooks belong to public books. Public books, that is, books with public copyright, refer to works published by writers and artists who are not restricted by copyright law. Their use will not infringe the author's copyright, so the dubbing of college textbooks will not infringe, but it is necessary to explain clearly what the material is.

Dubbing is the process of adding sound to movies or multimedia. In a narrow sense, it refers to the language dialogue in which the voice actor matches the voice for the role or replaces the role in the original film with other languages. At the same time, due to the mistakes and omissions in the voice, the process of restoring the dialogue for the segment by the original actor is also called dubbing. When recording a photographic work, the voice of the actor or singing voice is replaced by others, which is also called "dubbing".