Analysis of Emerging Video Codecs: Coding Tools, Compression Efficiency

Abstract

The video compression community, from technologists to customers, is affected by the competition between two lines of development for future video compression technology beyond high-efficiency video coding (HEVC): AV1, as developed by the industry-driven Alliance for Open Media (AOM), and Versatile Video Coding (VVC), as developed and studied by the Joint Video Experts Team (JVET) on Future Video Coding of ITU-T Video Coding Expert Group (VCEG) and International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) Motion Picture Experts Group (MPEG). Both groups have asserted that their respective codecs, AV1 and VVC, outperform the state-of-the-art HEVC. However, in many cases, related studies are evaluating video codec performances based on different test conditions, scenarios, or codec implementations, which makes comparisons sometimes unfair and at least difficult to interpret. This paper provides a neutral and well-balanced evaluation of compression and runtime performance for both AV1 and VVC codecs, using their respective reference models, in comparison to two HEVC codec implementations: HEVC Test Model (HM) as the HEVC standard reference model and x265 as a well-known open-source HEVC codec implementation. Comparison of differentiating features of AV1 and VVC over HEVC is also reported. Our main findings show that, based on an objective analysis, AV1 allows bitrate reduction of 10% in comparison to HM for the same peak signal-to-noise ratio (PSNR) and Structural SIMilarity (SSIM) quality scores while increasing encoding runtime by 55.5x. However, we show that this objective advantage in coding efficiency does not necessarily translate into gain in terms of subjective quality assessment. Overall, objective results show VVC to be the best candidate for compression technology beyond HEVC.