High-Throughput Hardware Design for the AV1 Decoder Switchable Loop Restoration Filters

This paper presents a high-throughput hardware design for the Switchable Loop Restoration Filter (SLRF) of the AOM Video 1 (AV1) video format. This hardware includes the two filters defined at the AV1 SLRF: the Separable Symmetric Normalized Wiener Filter (SSNWF) and the Dual Self- Guided Filter (DSGF). The SLRF is the last step in the AV1 loop restoration filters, and it is used to attenuate blurring artifacts, improving the subjective video quality and the coding efficiency. The designed hardware targeted the AV1 decoderand is able to process up to 4K Ultra-High Definition (4K UHD) videos (with 3840x2160 pixels) at 60 frames per second (fps) in real-time. In order to cover different scenarios, two other target throughputs were also evaluated: 4K UHD at 30fps and Full HD (FHD) (with 1920x1080 pixels) at 30fps. The architectures were synthesized for standard cells using the 40 nm TSMC library. The SSNWF and DSGF architectures used 37.38 Kgates and 177.58 kgates in all evaluated scenarios. Depending on the evaluated scenario, the SSNWF power dissipation varied from 8.25mWto 26.95mWand the DSGF power varied from 57.19 mW to 115.02 mW. This is the first paper in the literature presenting a hardware design for the AV1 SLRF with its two filters.