Detection of video double encoding with GOP size estimation

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Video Integrity Verification and GOP Size Estimation Via Generalized Variation of Prediction Footprint

The Variation of Prediction Footprint (VPF), formerly used in video forensics for double compression detection and GOP size estimation, is comprehensively investigated to improve its acquisition capabilities and extend its use to video sequences that contain bi-directional frames (B-frames). By relying on a universal rate-distortion analysis applied to a generic double compression scheme, we first explain the rationale behind the presence of the VPF in double compressed videos and then justify the need of exploiting a new source of information such as the motion vectors, to enhance the VPF acquisition process. Finally, we describe the shifted VPF induced by the presence of B-frames and detail how to compensate the shift to avoid misguided GOP size estimations. The experimental results show that the proposed Generalized VPF (G-VPF) technique outperforms the state of the art, not only in terms of double compression detection and GOP size estimation, but also in reducing computational time

Localization of Forgeries in MPEG-2 Video through GOP Size and DQ Analysis

This work addresses forgery localization in MPEG-2 compressed videos. The proposed method is based on the analysis of Double Quantization (DQ) traces in frames that were encoded twice as intra (i.e., I-frames). Employing a state-of-the-art method, such frames are located in the video under analysis by estimating the size of the Group Of Pictures (GOP) that was used in the first compression; then, the DQ analysis is devised for the MPEG-2 encoding scheme and applied to frames that were intra-coded in both the first and second compression. In such a way, regions that were manipulated between the two encodings are detected. Compared to existing methods based on double quantization analysis, the proposed scheme makes forgery localization possible on a wider range of settings

Environmental burdens of nutrient removal technologies for the treatment of anaerobic digestion supernatant and its integration in a sewage treatment plant.

The paper deals with the environmental analyses of different advanced biological nitrogen removal from anaerobic effluent

Life cycle assessment of nutrient removal technologies for the treatment of anaerobic digestion supernatant and its integration in a wastewater treatment plant

The supernatant resulting from the anaerobic digestion of sludge generated by wastewater treatment plants (WWTP) is an attractive flow for technologies such as partial nitritation-anammox (CANON), nitrite shortcut (NSC) and struvite crystallization processes (SCP). The high concentration of N and P and its low flow rate facilitate the removal of nutrients under more favorable conditions than in the main water line. Despite their operational and economic benefits, the environmental burdens of these technologies also need to be assessed to prove their feasibility under a more holistic perspective. The potential environmental implications of these technologies were assessed using life cycle assessment, first at pilot plant scale, later integrating them in a modeled full WWTP. Pilot plant results reported a much lower environmental impact for N removal technologies than SCP. Full-scale modeling, however, highlighted that the differences between technologies were not relevant once they are integrated in a WWTP. The impacts associated with the WWTP are slightly reduced in all categories except for eutrophication, where a substantial reduction was achieved using NSC, SCP, and especially when CANON and SCP were combined. This study emphasizes the need for assessing wastewater treatment technologies as part of a WWTP rather than as individual processes and the utility of modeling tools for doing so