@misc{HerglotzLeMoanMercat, author = {Herglotz, Christian and Le Moan, Steven and Mercat, Alexandre}, title = {Energy Reduction Opportunities in HDR Video Encoding}, series = {IEEE International Conference on Image Processing (ICIP)}, journal = {IEEE International Conference on Image Processing (ICIP)}, isbn = {979-8-3503-4939-9}, issn = {2381-8549}, doi = {10.1109/ICIP51287.2024.10647527}, abstract = {This paper investigates the energy consumption of video encoding for high dynamic range videos. Specifically, we compare the energy consumption of the compression process using 10 -bit input sequences, a tone-mapped 8 -bit input sequence at 10 -bit internal bit depth, and encoding an 8 -bit input sequence using an encoder with an internal bit depth of 8 bit. We find that linear scaling of the luminance and chrominance values leads to degradations of the visual quality, but that significant encoding complexity and thus encoding energy can be saved. An important reason for this is the availability of vector instructions, which are not available for the 10-bit encoder. Furthermore, we find that at sufficiently low target bitrates, the compression efficiency at an internal bit depth of 8 bit exceeds the compression efficiency of regular 10-bit encoding.}, language = {en} } @misc{MercatSainioLeMoanetal., author = {Mercat, Alexandre and Sainio, Joose and Le Moan, Steven and Herglotz, Christian}, title = {Do we need 10 bits? : assessing HEVC encoders for energy-efficient HDR video streaming}, series = {IEEE journal on emerging and selected topics in circuits and systems}, volume = {15}, journal = {IEEE journal on emerging and selected topics in circuits and systems}, number = {1}, publisher = {Institute of Electrical and Electronics Engineers (IEEE)}, address = {New York}, issn = {2156-3357}, doi = {10.1109/JETCAS.2025.3533041}, pages = {31 -- 43}, abstract = {High-dynamic range (HDR) video content has gained popularity due to its enhanced color depth and luminance range, but it also presents new challenges in terms of compression efficiency and energy consumption. In this paper, we present an in-depth study of the compression performance and energy efficiency of HDR video encoding using High-Efficiency Video Coding (HEVC). In addition to using a native 10-bit HDR encoding configuration as a reference, we explore whether applying tone mapping to an 8-bit representation before encoding can result in additional bitrate and energy savings without compromising visual quality. The main contributions of this work are as follows: 1) a detailed evaluation of four HDR video encoding configurations, three of which leverage tone mapping techniques, 2) a comprehensive experimental setup involving over 15,000 individual encodings across three open-source HEVC encoders (Kvazaar, x265, and SVT-HEVC) and multiple presets, 3) the use of two advanced perception-based metrics for BD-rate calculations, one of which is specifically tailored to capture colour distortions and 4) an open-source dataset consisting of all experimental results for further research. Among the three tone-mapping configurations tested, our findings show that a simple bit-shifting approach can achieves significant reductions in both bitrate and energy consumption compared to the native 10-bit HDR encoding configuration. This research aims to lay an initial foundation for understanding the balance between coding efficiency and energy consumption in HDR video encoding, offering valuable insights to guide future advancements in the field.}, language = {en} }