A Video Steganography for H.265/HEVC Based on Multiple CU Size and Block Structure Distortion

TL;DR

This paper introduces a novel video steganography method for H.265/HEVC that minimizes structural disruption and enhances anti-steganalysis by using multiple CU sizes and a three-level distortion strategy.

Contribution

It proposes a new algorithm with a CU Block Structure Stability Metric, a multi-CU size mapping rule, and a three-level distortion function to improve anti-steganalysis and embedding capacity.

Findings

Enhanced anti-steganalysis performance at low embedding rates.

Improved visual quality and embedding capacity over state-of-the-art methods.

Reduced bitrate increase ratio while maintaining concealment effectiveness.

Abstract

Video steganography based on block structure, which embeds secret information by modifying Coding Unit (CU) block structure of I-frames, is currently a research hotspot. However, the existing algorithms still suffer from the limitation of poor anti-steganalysis, which results from significantly disrupting the original CU block structure after embedding secret information. To overcome this limitation, this paper proposes a video steganography algorithm based on multiple CU size and block structure distortion. Our algorithm introduces three key innovations: 1) a CU Block Structure Stability Metric (CBSSM) based on CU block structure restoration phenomenon to reveal the reasons for the insufficient anti-steganalysis performance of current algorithms. 2) a novel mapping rule based on multiple CU size to reduce block structure change and enhance embedding capacity. 3) a three-level distortion function based on block structure to better guide the secret information embedding. This triple strategy ensures that the secret information embedding minimizes disruption to the original CU block structure while concealing it primarily in areas where block structure changes occur after recompression, ultimately enhancing the algorithm's anti-steganalysis. Comprehensive experimental results highlight the crucial role of the proposed CBSSM in evaluating anti-steganalysis performance even at a low embedding rate. Meanwhile, compared to State-of-the-Art video steganography algorithms based on block structure, our proposed steganography algorithm exhibits greater anti-steganalysis, as well as further improving visual quality, bitrate increase ratio and embedding capacity.