Abstract: In recent years, video steganography for H.265/HEVC attracted considerable attention. Among them, video methods that employ prediction unit (PU) as embedding carriers have become a research focus in this field. Such methods achieve information hiding by designing mapping rules between secret messages and PU. However, since the embedding of secret information induces substantial modifications to the prediction units, their resistance to steganalysis is relatively weak. To address this issue, this paper proposes a H.265/HEVC video steganography method based on PU directional mapping and multi-region embedding. The proposed method first extracts the partition mode combinations of two adjacent PU from 8×8 and 16×16 coding unit (CU), and maps them to a two-dimensional coordinate through directional mapping. Then, for different PU partition mode combinations, a multi-region embedding strategy is further designed to achieve high-capacity adaptive steganography with minimal modification distortion, thereby enhancing the method’s resistance to steganalysis. Experimental results demonstrate that the proposed method out-performs existing PU-based video steganography methods in terms of visual quality, bitrate control, and resistance to steganalysis. This method holds significant potential for applications in covert video communication. 

Key words: H.265/HEVC video steganography, PU partition mode, directional mapping, multi-region embedding, anti-steganalysis