A Fast Algorithm for Adaptive Motion Compensation Precision in Screen Content Coding

Fractional-pel motion compensation is very good at improving video coding efficiency, especially for camera-captured content. But for screen content, which is obtained from a computer desktop, motion vectors with integer-precision may be enough to represent the motion in different pictures. Using fractional-pel motion compensation for such content is a waste of bits. Thus, adaptive motion compensation precision is helpful for improving coding efficiency, especially for screen content coding. Usually, to select suitable motion compensation precision, multi-pass encoding is introduced, which significantly increases the encoding time. This paper presents a fast encoding algorithm for adaptive motion compensation precision used in screen content coding by hash-based block matching. With the proposed method, multi-pass encoding is avoided and most of the benefits brought by adaptive motion compensation precision are preserved. The experimental results show that with the proposed method, up to 7.7% bit saving is obtained without a significant impact on encoding time.