  The global significance of energy consumption of video communication renders
research on the energy need of video coding an important task. To do so,
usually, a dedicated setup is needed that measures the energy of the encoding
and decoding system. However, such measurements are costly and complex. To this
end, this paper presents the results of an exhaustive measurement series using
the x265 encoder implementation of HEVC and analyzes the relation between
encoding time and encoding energy. Finally, we introduce a simple encoding
energy estimation model which employs the encoding time of a lightweight
encoding process to estimate the encoding energy of complex encoding
configurations. The proposed model reaches a mean estimation error of 11.35%
when averaged over all presets. The results from this work are useful when the
encoding energy estimate is required to develop new energy-efficient video
compression algorithms.
