Mitigation of H.264 and H.265 Video Compression for Reliable PRNU Estimation

The photo-response non-uniformity (PRNU) is a distinctive image sensor characteristic, and an imaging device inadvertently introduces its sensor's PRNU into all media it captures. Therefore, the PRNU can be regarded as a camera fingerprint and used for source attribution. The imaging pipeline in a camera, however, involves various processing steps that are detrimental to PRNU estimation. In the context of photographic images, these challenges are successfully addressed and the method for estimating a sensor's PRNU pattern is well established. However, various additional challenges related to generation of videos remain largely untackled. With this perspective, this work introduces methods to mitigate disruptive effects of widely deployed H.264 and H.265 video compression standards on PRNU estimation. Our approach involves an intervention in the decoding process to eliminate a filtering procedure applied at the decoder to reduce blockiness. It also utilizes decoding parameters to develop a weighting scheme and adjust the contribution of video frames at the macroblock level to PRNU estimation process. Results obtained on videos captured by 28 cameras show that our approach increases the PRNU matching metric up to more than five times over the conventional estimation method tailored for photos

Live GPU Forensics: The Process of Recovering Video Frames from NVIDIA GPU

The purpose of this research is to apply a graphics processing unit (GPU) forensics method to recover video artifacts from NVIDIA GPU. The tested video specs are 512 x 512 in resolution for video 1 and 800 x 600 in resolution for video 2. Both videos are mpeg4 video codec. A VLC player was used in the experiment. A special program has been developed using OpenCL to recover 1) patterns that are frames consist of pixel values and 2) dump data from the GPU global memory. The dump data that represent the video frame were located using simple steps. The recovery process was successful. For 512 x 512 resolution video, the frames were partially recovered but it shows enough information for the forensics investigator to determine what was viewed last. The research indicates that it is harder, but not impossible, to obtain a viewable frame from higher-resolution vide

Audiovisual preservation strategies, data models and value-chains

This is a report on preservation strategies, models and value-chains for digital file-based audiovisual content. The report includes: (a)current and emerging value-chains and business-models for audiovisual preservation;(b) a comparison of preservation strategies for audiovisual content including their strengths and weaknesses, and(c) a review of current preservation metadata models, and requirements for extension to support audiovisual files