Detection of video double encoding with GOP size estimation

Abstract

Video forensics is an emerging discipline, that aims at inferring information about the processing history undergone by a digital video in a blind fashion. In this work we introduce a new forensic footprint and, based on it, propose a method for detecting whether a video has been encoded twice; if this is the case, we also estimate the size of the Group Of Pictures (GOP) employed during the first encoding. As shown in the experiments, the footprint proves to be very robust even in realistic settings (i.e., when encoding is carried out using typical compression rates), that are rarely addressed by existing techniques.

Detection of Double-Compressed H.264/AVC Video Incorporating the Features of the String of Data Bits and Skip Macroblocks

“…Table 5 shows the Holm test results, where the proposed method is set as the control method, the null hypothesis (H0) is set so that there is no difference between the control method and the comparative method, and the Holm p-value refers to the adjusted p-value of the first combination of the ranking that performs significantly worse than one of the best groups. It can be seen in Table 5 that for Stamm et al [20] and Vazquez-Padin et al [21], the hypothesis H0 are both rejected, in other words, the proposed method is apparently better than [20,21]. However, for He et al [22], the hypothesis H0 is accepted, that is, the proposed method is slightly better than [22] in terms of performance, but it is not improved significantly from a statistical point of view.…”

“…Figure 8 illustrates that, by using the enhanced feature of the string of the data bits, the interference of frame 75 has been partially suppressed and the periodicity for all peak values is detected. We also prepare the proposed method with other state-of-the-art methods, including He et al [22], Stamm et al [20] and Vazquez-Padin et al [21].…”

“…, T} generated in this method exhibits a more obvious periodicity than that of the other methods, especially in the case of videos with scene switching. To further demonstrate the superiority of the proposed method, we compare the detection performance of the proposed method with He et al [22], Stamm et al [20] and Vazquez-padin et al [21] by applying non-parametric statistical tests. We used the STAC platform [24] to conduct the tests of statistical significance on the previously presented experimental results, with the objective of determining if statistical differences existed among the proposed method and comparative approaches [20][21][22].…”

“…To further demonstrate the superiority of the proposed method, we compare the detection performance of the proposed method with He et al [22], Stamm et al [20] and Vazquez-padin et al [21] by applying non-parametric statistical tests. We used the STAC platform [24] to conduct the tests of statistical significance on the previously presented experimental results, with the objective of determining if statistical differences existed among the proposed method and comparative approaches [20][21][22]. Specifically, a Friedman ranking test [25] with a significance level of 0.05 was first performed, and the test results are presented in Table 4, where a lower rank indicates a better performance.…”

“…Stamm et al [20] proposed an automatic double-compression detection method for spectral peak characteristics based on the average prediction residuals of the P-frames. Vazquez-Padin et al [21] proposed a double-compression detection method based on the variation characteristics of the macroblock prediction type in the double coded P-frames and estimated the primary GOP size of the to-be-detected videos. For a double-compressed video with intense foreground motion, He et al [22] proposed a method to detect a double MPEG-4 compression based on a local motion vector field analysis, conducted after a static background segmentation.…”