The Research On Steganography Algorithm Based On ±1 DCT Coefficients For H.264 Video

Nowadays, as the rapid development of the internet and mobile internet, network security issues are increasingly attracting the attention of people. It's popular to use H.264 video as a carrier for information hidding in the field of network information security. Many steganography algorithms specially in the compressed domain for H.264 video are proposed.To improve current steganography algorithms whose carrier is the trailing ones coefficients, the steganography algorithm based on ±1 coefficients after discrete cosine transform(DCT) and quantization for H.264 video is proposed. The algorithm uses ±1 DCT coefficients to hide secret information. The algorithm embeds information bits differently on the number of ± 1 DCT coefficients. If the number of ± 1 DCT coefficients is less than 3, the algorithm make the number of ±1 DCT coefficients odd or even to embed bit ?1? or ?0?. If the number of ±1 DCT coefficients is more than or equal to 3, the algorithm embeds information bits by matrix encoding. The simulation results show that the algorithm can realize real-time embedding and extracting information and after embedding information the degradation of video quality is negligible and the same overall bitstream length is maintained.Furthermore, the improved steganography algorithm based on ±1 DCT coefficients for H.264 video is proposed. The improved algorithm embedds information in I-frames and prevent the distortion incurred in pixel values. The simulation results show that after the improved algorithm embeds information the video is the same to the original video in the visual and PSNR andoverall bitstream length is maintained. The comparision with other two algorithms shows the superiority of the improved algorithm in PSNR degradation and that in bitstream overlength percent the improved algorithm is better than one algorithm and worse than another algorithm.At last, embedding information by using x264(the best H.264/AVC encoder) when encoding H.264 video and extracting information by using ffmpeg(a H.264/AVC decoder) when decoding H.264 video are achieved with the ±1 DCT algorithm and the improved algorithm.