Improving compression efficiency of HEVC using perceptual coding
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Improving compression efficiency of HEVC using perceptual coding Sima Valizadeh 1
1
& Panos Nasiopoulos & Rabab Ward
1
Received: 12 September 2019 / Revised: 14 June 2020 / Accepted: 28 July 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
The introduction of the new coding tools in HEVC has brought significant bitrate savings compared to the previous standard, H.264/AVC. In both standards, the mean square error (MSE) is used for measuring distortion in the rate distortion optimization process of the coding unit structure and mode selection. However, MSE is not a good measure to use for measuring visual quality as it poorly correlates with human perception. Integration of a video quality metric based on the characteristics of the Human Visual System (HVS) inside the rate distortion optimization procedure is expected to improve the compression efficiency of video coding. In this paper, the PSNR-HVS measure is used in the rate distortion optimization process for the coding unit structure and mode selection. In the first step, we find the scaling factor for the Lagrangian multiplier based on the proposed perceptual approach. In the second step, we find optimal Lagrangian multiplier depending on the quantization parameter. The compression efficiency of the proposed approach is compared to that of HEVC. Simulations prove that the proposed approach yields higher compression efficiency. Keywords Perceptual video coding . Rate distortion optimization (RDO) . Human visual system (HVS) . PSNR-HVS . High efficiency video coding (HEVC) . Coding unit structure . CU mode selection
* Sima Valizadeh [email protected] Panos Nasiopoulos [email protected] Rabab Ward [email protected]
1
University of British Columbia, Vancouver, Canada
Multimedia Tools and Applications
1 Introduction Advances in video compression have enabled us to achieve high visual quality with constrained amounts of bitrate. Achieving higher compression efficiency is crucial for limited capacity communication channels and storage media in consumer electronics. Additionally, offering new services such as higher resolution video, more sophisticated multimedia applications and ultra-high definition television depend on higher video compression efficiency. To address these challenges, a new video coding standard was developed by collaboration between the ITU-T Visual Coding Experts Group (VCEG) and the ISO-IEC Moving Picture Experts Group (MPEG). The new standard is called HEVC and was completed in January 2013. HEVC introduces new tools such as variable size for coding units and prediction units, extended intra prediction modes, advanced motion vector prediction and block merge method [31]. HEVC provides 50% better video compression than the previous video coding standard, H.264/AVC. Experiments with the new video coding standard, high efficiency video coding show that more than half of its average bit-rate savings relative to its predecessor, H.264/ MPEG-4 AVC, comes from its increased flexibility of block partitioning for
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