Implementation of film grain technology with VVC

Film grain is often desirable feature in video production. Content creators can use film grain to create a natural appearance and to express their creative-artistic impression. With the expansion of the streaming services, prior to delivery, video typically undergo various pre-processing steps, where the inevitable video compression is presented. Modern video compression standards, such as recently issued Versatile Video Coding (VVC) also known as ITU-T H.266 and ISO/IEC 23090-3, do not favour film grain, and are not able to distinct it as a desirable feature. Rather, within various filtering and lossy compression steps, film grain is suppressed without the possibility of reconstructing it. One option to alleviate this problem is to use lower quantization parameters to better preserve fine details such as film grain. However, this may strongly increase the bitrates. Another solution is to model the film grain prior to compression, which later-on can be resynthesized on the decoder side. Since film grain technology is becoming increasingly popular in video delivery and distribution applications, it is supported in the Versatile supplemental enhancement information messages (VSEI, also known as ITU-T Recommendation H.274 and ISO/IEC 23002-7). This paper provides an overview of the film grain modelling, parametrization, and signalling, and presents an implementation of film grain in the context of novel VVC standard. An approach based on the frequency filtering is summarized, with a quantitative and qualitative analysis, where the benefits of film grain parametrization in terms of the BD-rate savings for the same perceived quality are shown. We further focus our work on film grain parameters estimation and synthesis, specifically in the context of VVC, where we plan to propose several modifications and improvements of the state-of-the-art approaches.