FastInter360: A Fast Inter Mode Decision for HEVC 360 Video Coding
Iago Storch, Luciano Agostini, Bruno Zatt, Sérgio Bampi, Daniel Palomino
Abstract
This paper presents FastInter360, a fast inter mode decision algorithm for accelerating the encoding of ERP 360 videos. The development of FastInter360 involves an in-depth and comprehensive set of evaluations performed to understand the differences in the encoder’s behavior when encoding 360 and conventional videos. These evaluations showed that due to the texture distortions resulting from projection, the encoder presents a specific behavior when encoding 360 videos, making it more likely to use a recurrent set of encoding modes when processing 360 videos. Besides, the coding efficiency is less sensible to approximations in some encoding steps depending on the frame region. FastInter360 is then proposed to reduce the encoding complexity by exploiting these differences. FastInter360 comprises three algorithms that accelerate the encoding by performing early decision by SKIP mode, reducing integer motion estimation search range, and adjusting fractional motion estimation precision. Furthermore, each of these algorithms behaves according to distortion intensity, performing greater complexity reduction in more distorted regions. When employed altogether, these algorithms compose FastInter360, which is able to achieve an average complexity reduction of 22.84% with a coding efficiency loss of 0.652% BD-BR, on average, making FastInter360 competitive with literature works.