Low-Power and High-Throughput Approximated Architecture for AV1 FME Interpolation

Modern video encoders like the AOM Video 1 (AV1) implement several complex tools to allow the required high level of compression efficiency. The Fractional Motion Estimation (FME) is one of these tools and in AV1 the FME defines 90 different filters. To handle such complexity, hardware acceleration using approximate computing has become an alternative to be explored. This paper presents an approximate solution for the AV1 FME interpolation filters based on the approximation of the original filter coefficients intending to generate more hardware friendly coefficients. The approximated version was designed in hardware and can achieve real-time interpolation for UHD 8K videos at 30 frames per second, when synthesized using 40nm TSMC standard-cells technology. The designed architecture dissipates 26.79mW which represents more than 80% power reduction when compared to the original precise solution. The approximation implied in a small average coding efficiency degradation of 0.54% in BD-BR. When comparing with related works, this architecture reaches an expressive power reduction (2.1 to 4.8 times) even supporting more complex tools.