Bit-stream-based scrambling for regions of interest in H.264/AVC videos with drift reduction

We propose a new scrambling approach for regions of interest in compressed H.264/AVC bit streams. By scrambling at bit stream level and applying drift reduction techniques, we reduce the processing time by up to 45% compared to full re-encoding. Depending on the input video quality, our approach induces an overhead between −0.5 and 1.5% (high resolution sequences) and −0.5 and 3% (low resolution sequences), respectively, to reduce the drift outside the regions of interest. The quality degradation in these regions remains small in most cases, and moderate in a worst-case scenario with a high number of small regions of interest.