Adaptive complexity control for AV1 video encoder using machine learning

Digital videos are widely used on various platforms, including smartphones and other battery-powered mobile devices, which can suffer from energy consumption and performance constraints. Video encoders are responsible for compressing video data, enabling the use of this type of media by reducing the data rate while maintaining image quality. To promote the use of digital videos, the continuous improvement of digital video encoding standards is crucial. In this context, the Alliance for Open Media (AOM) developed the AV1 (AOMedia Video 1) format. However, the advanced tools and enhancements provided by AV1 come with a high computational cost. To address this issue, this paper presents the learning-based AV1 complexity controller (LACCO). The goal of LACCO is to dynamically optimize the encoding time of the AV1 encoder for HD 1080 and UHD 4K resolution videos. The controller achieves this goal by predicting the encoding time of future frames and classifying input videos according to their characteristics through the use of trained machine learning models. LACCO was integrated into the reference software of the AV1 encoder and its encoding time reduction ranges from 10 to 70%, with average error results ranging from 0.11 to 1.88 percentage points for HD 1080 resolution and from 0.14 to 3.33 percentage points for UHD 4K resolution.