Arbitrary-sized motion detection in screen video coding

In real-time screen remoting system, frame rate is one of essential factors that affect user experience. Therefore, how to compress diversity of screen contents fast and efficiently is a key issue. Existing video codecs such as H.264 are always used in such a system for screen compression. However, arbitrary-sized regions with large motion always exist in typical screen content videos, which lead to a lower encoding speed and higher bit-rate, thereby decrease the frame rate. This paper proposes an efficient motion detection algorithm, which is fast and efficient for large motion regions. In specific, a region-based motion detection is used to find motion vectors instead of traditional block based motion estimation. The motion vectors are then utilized by H.264 encoder for normal motion compensated prediction. Experimental results show that the proposed algorithm can reduce both encoding time and bit-rate significantly.