Position-based Motion Vector Prediction for Textual Image Coding

Donghui Feng, Chen Zhu, Guo Lu, Li Song

Abstract: Textual content is becoming increasingly important in video conferencing, while existing screen content encoding tools still produce a high bitrate in text regions. The main coding tool Intra Block Copy (IBC) inherits the MV prediction mechanism in inter-frame coding, but the adjacent text characters typically have irrelevant MVs, making it inefficient to predict MV using only neighbor MVs. To solve the problem, we propose the Position-based Motion Vector Prediction, to cache IBC AMVP PU positions as predictors. One character can find the previously encoded position to construct a good MV prediction. Experiment results show the effectiveness of the proposed prediction scheme.