Region-based H.263+ coding for real-time video communication

This paper proposes a novel low-complexity region-based video-coding algorithm that automatically identifies moving foreground objects, compresses them with higher quality than the background and efficiently encodes the video in an H.263+ compliant bitstream. Global motion estimation is first performed using the MSE algorithm. The original sequence is then segmented into foreground and background regions by using global and local motion information predicted from the previous frame. This enables the separation of moving objects with respect to a static background, even in the presence of camera motion. A modified TMN8 rate control algorithm is proposed to assign more bits to the foreground region, and the segmented video is then encoded into an H.263+ compliant bitstream. As block-matching motion estimation is used to obtain the local motion field and foreground/background identification is also block-based, the proposed algorithm has lower complexity than previously proposed pixel-based algorithms. Hence it is can be easily implemented in software or ASIC-based real-time applications. It is also particularly useful for mobile applications where bandwidth is highly constrained and low power requirements restrict processing complexity.