Optimal Frame Rate Selection of Screen Content Video and Its Application in Perceptual Versatile Video Coding

Screen content videos (SCV) containing text, graphics, icons, and charts are widely used in distance education, screen sharing, and other fields. In these fields, SCV coding plays a critical role which pursues higher reconstructed video quality with lower coding bitrate. And, the selection of frame rate significantly affects the SCV coding efficiency. In addition to motion intensity, smoothness of motion change is also an important factor affecting the selection of frame rate, but it is ignored by current researches. In this paper, targeting at SCV, metrics that effectively quantify smoothness of motion change and motion intensity are first constructed. Then, the impacts of smoothness of motion change and motion intensity on frame rate selection are further explored and modeled. Finally, an optimal frame rate selection method is proposed and is further applied to the state-of-the-art versatile video coding (VVC) standard to significantly improves the SCV coding efficiency. Compared with the traditional method adopted in the VVC test model (i.e., VTM), the proposed method can achieve the average BD-rate reductions of 27.14%.

I. Introduction

As a new type of video, screen content video (SCV) generated or rendered by computer is widely used in the distance education, screen sharing, and other fields [1, 2]. Fig 1 shows two standard SCVs. As shown in Fig 1, SCV mainly includes text, graphics, icons, and charts. Different from natural video captured by camera, SCV usually contains more irregular motion and more sharp edges exist in text and graphic regions, and the geometries of these edges are usually complicated [1 –3].