Characterizing energy consumption in software HEVC encoders: HM vs x265

Abstract

Nowadays, digital video processing has become an important challenge when developing digital systems, mainly in terms of energy consumption. The High Efficiency Video Coding (HEVC) is the state-of-the-art video coding standard and the energy profiling of different HEVC encoder implementations is of key importance. HEVC encoder has different implementations developed for different goals. This work presents a comparison between the commercial encoder x265 and the reference software HM (HEVC Test Model). The Running Average Power Limit (RAPL) tool was utilized to measure the energy consumption of HM and x265 encoders for different configurations. Both results were compared to estimate the performance differences between such encoders. Based on the obtained results it can be seen that x265 achieves a higher coding efficiency for all studied configurations, reaching on the best case a gain of 9% on the coding efficiency, whereas consuming the same amount of energy than HM. The results also demonstrate that x265 has the characteristics of high consumption, small coding efficiency loss, and high adaptability, which are desirable to perform energy control on the encoder, and that some of its tools can reduce the energy consumption around 25% with small performance losses.