Enhancing SVT-AV1 with LCEVC to improve quality-cycles trade-offs and enhance sustainability of VOD transcoding

The trade-offs between compression performance and encoding complexity are key in software video encoding, even more so with increasing pressure on sustainability. Previous work "Towards much better SVT-AV1 quality-cycles trade-offs for VOD applications" [1] described three approaches of evaluating compression efficiency vs cycles trade-offs within a convex-hull framework using the Dynamic Optimizer (DO) algorithm developed in [2] [3] for VOD applications. In parallel, the new video codec enhancer LCEVC (Low Complexity Enhancement Video Coding) [4], designed to provide gains in speed-quality trade-offs, has recently been standardized as MPEG-5 Part 2. The core idea of LCEVC is to use any video coding standard (such as AV1) as a base encoder at a lower resolution, and then reduce artifacts and reconstruct a full resolution output by combining the decoded low-resolution output with up to two low-complexity reconstruction enhancement sub-layers of the residual data. This paper starts by applying LCEVC to SVT-AV1 [5], as well as x264 [6] and x265 [7], while using two of the approaches presented in [1] to evaluate the resulting compression efficiency vs cycles trade-offs. The paper then discusses the benefits of LCEVC towards higher playback speed and lower battery power consumption when using AV1 software decoding. Results show that, with fast-encoding parameter selection using the discrete convex hull methodology, LCEVC improves the quality-cycles trade-offs for all the tested codecs and across the full complexity range. In the case of SVT-AV1, LCEVC yields a similar to 40% reduction in computations while achieving the same quality levels according to VMAF_NEG [8]. LCEVC also enlarges the set of mobile devices capable of playing HD as well as high-frame-rate content encoded with AV1 and extends mobile battery life by up to 50% with respect to state-of-the-art AV1 software decoding.