Impact of Screencasting on Video Temporal Synchronization
Spatio-temporal desynchronization remains a major challenge for watermarking system as it could impair the detection of the hidden payload. Over the years, several (non-blind) registration techniques have been proposed to realign the analyzed content prior to watermark detection and thereby achieve robustness against severe attacks such as display-and-camcord. Such techniques rely on assumptions that may be invalidated by new attacks that had not been accounted for. In the case of video, for instance, best-in-class resynchronization techniques may have difficulties to cope with screencasting. In this paper, we report findings after an experimental study that involved five popular screencasting tools. The impact of screencasting can indeed be characterized in terms of frame drops and repeats. Moreover, the on-the-fly encoding process occurring during screen recapture inherently introduces dependencies between the likelihood of drop/repeat and the frame encoding type.
