The emerging 360-degree video has a good practical prospect in video broadcasting due to its more immersive experience than traditional videos. To maintain a high fidelity with panoramic vision, 360-degree video adopts a significantly increased resolution than planar videos, which also inevitably leads to higher encoding complexity. In this paper, we propose a flexible complexity optimization method for 360-degree video coding, in which the encoder is capable of adapting to different complexity constraints in diversified broadcasting scenarios. In particular, the proposed method is realized with a latitude-based computation complexity allocation. Firstly, it investigates the Coding Unit (CU) partition variation along the latitude (i.e., vertical axis) and divides each video frame into Largest CU (LCU)-based latitude regions. Then, it formulates the complexity allocation problem from the global complexity target to all latitude regions, by considering the intraframe dependencies and Rate-Distortion (RD) models. Finally, it calculates the solution to this complexity allocation problem and further employs it in 360-degree video coding. Comprehensive experiments on the standard dataset reveal the superiority of our method, which achieves a flexible computational time reduction from 14.53% to 68.36% whilst maintaining a high visual quality of compressed videos.

中文翻译：

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360 度视频编码的基于纬度的灵活复杂度分配

新兴的 360 度视频因其比传统视频更具沉浸感的体验，在视频播放中具有良好的实践前景。为了保持全景视觉的高保真度，360 度视频采用比平面视频显着提高的分辨率，这也不可避免地导致更高的编码复杂度。在本文中，我们提出了一种灵活的 360 度视频编码复杂度优化方法，其中编码器能够适应多样化广播场景中的不同复杂度约束。特别是，所提出的方法是通过基于纬度的计算复杂度分配来实现的。首先，它研究沿纬度（即垂直轴）的编码单元（CU）分区变化，并将每个视频帧划分为基于最大CU（LCU）的纬度区域。然后，它通过考虑帧内依赖性和速率失真（RD）模型，制定了从全局复杂度目标到所有纬度区域的复杂度分配问题。最后，它计算了这个复杂度分配问题的解决方案，并进一步将其应用于 360 度视频编码。在标准数据集上的综合实验揭示了我们方法的优越性，它实现了从 14.53% 到 68.36% 的灵活计算时间减少，同时保持压缩视频的高视觉质量。