Gain of Grain: A Film Grain Handling Toolchain for VVC-based Open Implementations

TL;DR

The paper tackles the challenge of preserving film grain in VVC-based encoding while maintaining compression efficiency. It introduces a film grain handling toolchain integrated with open VVC implementations, combining denoising (via MCTF), frequency-based grain estimation, SEI-based parameter transmission, and post-decoding grain synthesis from a SMPTE-RDD5 pattern bank. The approach demonstrates perceptual quality gains at multiple bitrates, analyzes rate-distortion behavior, and reveals encoding/decoding time trade-offs across presets and adaptive streaming scenarios. The work enables high-fidelity grain-rich content in open VVC pipelines and informs future perceptual metrics and grain modeling directions.

Abstract

Film grain is a distinctive visual characteristic cherished by filmmakers and cinephiles for its ability to evoke nostalgia and artistic aesthetics. However, faithful preservation of film grain during encoding poses unique challenges. Film grain introduces random noise, complicating traditional compression techniques. Consequently, specialized algorithms and encoding strategies have emerged, aiming to strike a harmonious equilibrium. This paper delves into the nuanced realm of film grain handling in Versatile Video Coding (VVC) encoding. We explore the delicate balance between retaining the cinematic charm of film grain and achieving efficient compression. Moreover, we discuss the importance of perceptual quality assessment and adaptive encoding techniques in preserving film grain fidelity. Additionally, we delve into the impact of film grain handling on bitrate control and compression efficiency using VVenC, an open and optimized VVC encoder. Understanding the role of film grain and its nuanced treatment within encoders becomes increasingly pivotal for delivering high-quality, grain-inclusive content in the digital age.

Figures (6)

• Figure 1: Illustration of compression artifacts introduced due to film grain when encoded using VVenC encoder at low bitrates.
• Figure 2: State-of-the-art film grain handling toolchain framework.
• Figure 3: Film grain handling toolchain considered in this paper.
• Figure 4: Comparison of (a) original sequence, (b) encoded at 3 Mbps with MCTF, and (c) encoded at 3 Mbps with the proposed toolchain (with FGS) of the representative (cropped) frame of OldTownCross sequence.
• Figure 5: Comparison of the representative (cropped) frame of IntoTree test sequence encoded at 0.25 Mbps.