# Research on Quantization Parameter Decision Scheme for High Efficiency Video Coding
## 1 Introduction  
With the development of communication technology, video collection technology, computation storage, and transmission technology, the types of videos are gradually diversifying. Video can be divided into 2 Dof video, 3 Dof video, and 6 Dof video according to the degree of freedom (Dof). Different from traditional 2 Dof video, 360-degree panoramic video has three degrees of freedom. It is a sphere video that contains the entire environment. Furthermore, it provides users with an immersive experience and is expected to be widely used in the future. In order to ensure a better immersive experience for users, 360-degree panoramic video has a higher resolution [1], which greatly increases the amount of video data and brings great challenges to both storage and transmission. Therefore, panoramic videos must be compressed before being transmitted on the Internet. However, there is no framework for directly compressing and encoding panoramic videos; 360-degree panoramic videos need to be converted into two-dimensional videos for encoding. Therefore, the compression of 360-degree panoramic video is of great significance. Up to now, researchers have developed a variety of coding standards. In 1990, the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) developed the H.261 video coding standard. The block-based hybrid coding framework proposed by this standard is still used. The hybrid coding framework combines prediction with transform. During the encoding, the residual information is obtained by performing intra-frame or inter-frame prediction on the video source information, followed by transform and quantization. After performing a series of inverse quantization and inverse transformation operations at the decoding end, the decoded video sequence is generated. However, with the updates of technology, the H.261 standard has only a few applications in transmission scenarios with extremely low bitrate requirements. In order to be suitable for application scenarios such as video conferencing and television communication, ITU-T promulgated the H.263 encoding standard in 1996 [2]. Compared to the H.261 encoding standard, the H.263 standard has better compression performance and more advanced features, but the encoding delay is slightly higher than the H.261 standard. In 1998, ITU-T released the H.263+ coding standard [3] based on the H.263 coding standard. The H.263+ standard achieves the purpose of improving video quality by adding some new coding tools. Among them, the new technologies include more accurate motion estimation, higher entropy coding efficiency, and better coding mode selection. These technologies allow H.263+ to provide better video quality at the same bitrate as H.263 or to consume a lower bitrate at the same video quality as H.263. The H.263+ standard has been widely used in fields such as video conferencing and video streaming and also provides basic technology for subsequent international video coding standards. With the development of information technology and multimedia applications, the H.263+ standard could no longer meet the commands of video coding transmission and communication, and the H.264/AVC coding standard [4] was provided. The H.264 encoding standard greatly improves video compression performance based on the H.263+ standard and is widely used in various video applications, attracting many video coding scholars to conduct optimization research on this standard. At present, the H.264 encoding standard is still the most widely used video encoding standard in the industry and is mainly used in fields such as digital TV broadcasting, video real-time communication, and video on demand. Today, video applications are becoming increasingly diversified. A large number of videos in different formats and rich content can provide for various needs, such as entertainment and leisure. Moreover, they bring more visual effects to users because of higher resolution and wider viewing port.