Video Brightness-Aware Encoding to Optimize Energy Consumption in HTTP Adaptive Streaming

The climate crisis has heightened attention on the environmental impacts of information and communication technologies (ICT), emphasizing the need for sustainable approaches to reduce carbon emissions. With video streaming dominating Internet traffic, its energy footprint warrants particular focus. The European Union's Corporate Sustainability Reporting Directive (CSRD) mandates that large and listed companies disclose social and environmental risks and impacts, using the European Sustainability Reporting Standards (ESRS) starting with fiscal year 2024. This paper presents brightness-aware encoding approaches for HTTP adaptive streaming to reduce overall energy use while preserving acceptable visual quality. We implement a full streaming pipeline (server and client), conduct content analysis to adapt brightness at the frame or scene level, and compare power consumption at both ends. We evaluate several brightness reduction modes on TVs and smartphones. Results show a small increase in server-side energy due to analysis and re-encoding, but substantial client-side savings - up to 25.7% on an OLED TV - demonstrating the practical potential of brightness-aware streaming.