rate control plays a crucial role in video coding. Existing rate control methods for high efficiency video coding standard (HEVC) hardly take advantage of spatio-temporal context information when updating model parame...
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rate control plays a crucial role in video coding. Existing rate control methods for high efficiency video coding standard (HEVC) hardly take advantage of spatio-temporal context information when updating model parameters, resulting in inaccurate computation of the Lagrange multiplier and quantization parameter (QP). Meanwhile, these methods fail to consider the motion complexity of a basic unit (BU). Therefore, a large mismatch may exist between the allocated bits and actually encoded bits. In this paper, we propose an effective rate control scheme for HEVC at the BU layer to exploit both the spatio-temporal context and motion complexity. Firstly, the actually used Lagrange multiplier and generated bits of the highly correlated coded BUs in the spatio-temporal context are carefully weighted to update the model parameters. Secondly, the allocated bits for a BU are adjusted based on its motion complexity. Thus, an improved Lagrange multiplier is more accurate in minimizing the difference between the target bits and actually generated bits. Experimental results show that our proposed method outperforms the current scheme in HM with negligible complexity increase.
rate control is a useful tool for video coding, especially in real-time communication applications. Most of existing rate control algorithms are based on the r - Q model, which characterizes the relationship between b...
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rate control is a useful tool for video coding, especially in real-time communication applications. Most of existing rate control algorithms are based on the r - Q model, which characterizes the relationship between bitrate r and quantization Q, under the assumption that Q is the critical factor on rate control. However, with the video coding schemes becoming more and more flexible, it is very difficult to accurately model the r - Q relationship. In fact, we find that there exists a more robust correspondence between r and the Lagrange multiplierlambda. Therefore, in this paper, we propose a novel lambda-domain rate control algorithm based on the r - lambda model, and implement it in the newest video coding standard high efficiency video coding (HEVC). Experimental results show that the proposed lambda-domain rate control can achieve the target bitrates more accurately than the original rate control algorithm in the HEVC reference software as well as obtain significant r-D performance gain. Thanks to the high accurate rate control algorithm, hierarchical bit allocation can be enabled in the implemented video coding scheme, which can bring additional r-D performance gain. Experimental results demonstrate that the proposed lambda-domain rate control algorithm is effective for HEVC, which outperforms the r - Q model based rate control in HM-8.0 (HEVC reference software) by 0.55 dB on average and up to 1.81 dB for low delay coding structure, and 1.08 dB on average and up to 3.77 dB forrandom access coding structure. The proposed lambda domain rate control algorithm has already been adopted by Joint Collaborative Team on Video Coding and integrated into the HEVC reference software.
rate control (rC) is an important tool that helps to control the bit rate of the compressed media. Current HEVC implementations include an rC algorithm, based on a r - lambda model, that does not consider the wide ran...
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ISBN:
(纸本)9781509021758
rate control (rC) is an important tool that helps to control the bit rate of the compressed media. Current HEVC implementations include an rC algorithm, based on a r - lambda model, that does not consider the wide range of luma values depicted in HDr content. This paper proposes a multi-r - lambda-model approach forrC in HEVC that accurately attains a target bit rate while improving the reconstruction quality of HDr content, especially for very bright regions. results, in terms of the mP-SNr and HDr-VDP-2 metrics, confirm the advantages of our approach compared to the current rC algorithm in HEVC.
rate control plays an important role in video coding, which can minimize the distortion of compressed video with bit rate constraints. rate control algorithm based on r - lambda model is capable of controlling the bit...
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rate control plays an important role in video coding, which can minimize the distortion of compressed video with bit rate constraints. rate control algorithm based on r - lambda model is capable of controlling the bit rate precisely for high efficiency video coding (HEVC). However, quality dependency is not considered very well in lambda-domain rate control algorithm when allocating bits and updating model parameters. This paper proposes a rate control algorithm based on group of pictures (GOP) level quality dependency for low-delay hierarchical coding structure. Firstly, the quality dependency between the current GOP and encoded GOPs mainly comes from the crucial frame (C-Frame). C-Frame guided GOP level quality dependency (CF-GOP-QD) model can be expressed by a CF-GOP-QD factor. Secondly, a CF-GOP-QD model based GOP level rate-distortion optimization (rDO) under the total bit constraints is proposed to guide the bit allocation processing, which is better than traditional bit allocation method. Experimental results show that the proposed rate control algorithm can achieve betterrate-distortion performance, better visual quality and betterrate control accuracy. Specifically, the proposed method shows 5.801% and 5.068% BD-rate saving on average compared against HM16.7 frame level rate control method under low-delay B and low-delay P configurations.
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