Region-of-interest-based rate control scheme for high-efficiency video coding

Abstract

International audienceThis paper presents a novel rate control scheme designed for the newest high efficiency video coding (HEVC) standard, and aimed at enhancing the quality of regions of interest (ROI) for a videoconferencing system. It is designed to consider the different regions at both frame level and coding tree unit (CTU) level. The proposed approach allocates a higher bit rate to the region of interest while keeping the global bit rate close to the assigned target value. The ROIs, typically faces in this application, are automatically detected and each CTU is classified in a region of interest map. This binary map is given as input to the rate control algorithm and the bit allocation is made accordingly. The algorithm is tested, first, using the initial version of the controller introduced in HEVC test model (HM.10), then, extended in HM.13. In this work, we first investigate the impact of differentiated bit allocation between the two regions using a fixed bit rate ratio in intra-coded frames (I-frames) and Bidirectionally predicted frames (B-frames). Then, unit quantization parameters (QPs) are computed independently for CTUs of different regions. The proposed approach has been compared to the reference controller implemented in HM and to a ROI-based rate control algorithm initially proposed for H.264 that we adopted to HEVC and implemented in HM.9. Experimental results show that our scheme has comparable performances with the ROI-based controller proposed for H.264. It achieves accurate target bit rates and provides an improvement in region of interest quality, both in objective metrics (up to 2dB in PSNR) and based on subjective quality evaluation

Video Quality Evaluation for Tile-Based Spatial Adaptation

“…Examples include sprite coding [3], MPEG-4 Visual Objects [4], [5] and other more recent ROI-based bit allocation schemes for H.264/AVC and H.265/HEVC [6], [7], [8], [9], [10], [11]. In most cases, ROI-based allocation targets specific applications scenarios, e.g., assigning higher quality to faces in teleconferencing [8], [10]. Previous work demonstrates that a proper rate allocation strategy might lead to substantial (albeit content-dependent [12]) gains in terms of perceived visual quality.…”

A Foreground-Background-Based CTU λ Decision Algorithm for HEVC Rate Control of Surveillance Videos

“…Li et al [5] study the bit allocation scheme for the foreground and background separately, but the most important parameter (λ) is not considered carefully. The authors of [6] calculate the λ values for ROI and non-ROI with the independent bit rate allocation. However, there is no theoretical basis to verify the efficiency, and the calculated λ may not be optimal without limitation.…”

Graph-Based Rate Control in Pathology Imaging With Lossless Region of Interest Coding

“…In the more general context of natural imaging data, important block-based PTC methods that combine RC and RoI coding may be found in the literature [16]- [17]. The work in [16] presents a scalable RoI coding method for H.264/SVC that employs a control mechanism that adjusts the quality of the RoI and non-RoI enhancement layers.…”

“…The work in [23] proposes an RC scheme for RoI coding of screen-content videos in H.264/AVC by employing several R-D models. In [17], Meddeb et al propose an RC algorithm for RoI coding in HEVC aimed at videoconferencing. Their algorithm assigns more bits to faces by employing two distinct R-D models.…”