Research On The Information Hiding Techniques For Video Encoded With HEVC

Informat ion hid ing re fers to the technique that e mbeds secret infor mat ion into digital te xt,ima ge,audio and video and other carriers and achie ves the purpose of secret communicat ion in a non-perceivab le way.D igital video is character ized for its large vo lume of data,and it is us ua lly stored and trans mitted after compression.Therefore,the comb inat io n of informat io n hiding technique with video coding process and standard is the ma instrea m of video informat io n hid ing techniq ues.HEVC is the latest inter nat iona l video coding standard specifically designed for the encoding o f high-definit io n(HD)and Ultra-HD video.Video infor mat ion hid ing for HEVC video is becoming the prior topic in the field of information hiding.For infor mat ion hid ing,the key is to ensure the vis ual d istortio n as sma ll as possib le,and less bitrate increase after embedding secret informat io n.HEVC still adopts the hybr id coding fra mework similar to MPEG-x and H.26 x,but it introduces some new featur ing tools.In this thesis,informat io n hid ing sche mes wit h high visua l qualit y and less bitrate increase are invest igate d,whic h fully cons iders the characterist ics o f HEVC video coding standard.Specifica lly,t he ma in work and contribut ions are summarized as follows:First ly,comb ining t he feat ur ing tool o f s ign data hid ing(SDH),a data hid ing scheme is proposed for HEVC by exp loit ing the rate-distort ion optimizat ion of video encoder.SDH itse lf is a technique of data hid ing,and one of featur ing techniques of HEVC as well.SDH increases or decreases 1 from t he quant ized coeffic ie nts to reach the purpose of hidden symbol b it.Since the embedding and the symbol hid ing of SDH are executed simultaneous ly,which reduces the number of coeffic ient alterations.Further,the embedded posit io n is located ins ide the construct ion loop of HEVC encoder.That is,the embedding process is direct ly invo lved in t he select ion o f optima l predict ion mode.Video encoder selects the predict io n mode with t he sma llest cost of b itrate increase and distort ion,whic h guarantees t he vis ual q ua lity a fter informat io n hid ing.Experime nta l results s how that t he proposed approach has a cons iderable embedding capacit y,and t he bit rate increase and perceptua l qua lit y degradation is also guaranteed,embedding rate is above 40%.Second,for those video applicat ion sens it ive to bitrate,a new concept of constant bitrate informat io n b it substit ut ion is introduced,and a CABAC entropy coding based video steganography approach wit hout b itrate increase is proposed.Most exist ing video infor mat ion hid ing algorit hms will cause a large bitrate increase when secret data is embedded.By ana lyzing the characterist ics of the entropy coding met hod CABAC in the aspects of syntax e le ments and coding details,a nove l concept of “constant bitrate information bit substitution” is introduced.By fully exploiting the large amo unts of “constant bitrate infor mat ion bits ” for the mot ion vector residua ls(MVD)in HEVC,a codeword reservat ion and s ubstit ut ion r ule is designed for the encoding of M VDs,and a high-capacity video steganography a lgor it hm is presented for HEVC video based on CABAC.Since video stegano graphy is conducted dur ing the period of entropy coding,it does not need comp lex operations s uch as rate distortio n optimizat ion(RDO)and full decoding.Moreover,it is based on constant bitrate infor mat ion b it subst it ut ion,so it will not lead to any b itrate increase.Experime nta l results on several test sequences show that the proposed HEVC video steganography approach is effective.