4K Real-Time and Parallel Software Video Decoder for Multilayer HEVC Extensions

Two High Efficiency Video Coding (HEVC) extensions, namely, the scalable HEVC (SHVC) extension and the multiview HEVC (MV-HEVC) extension, have been finalized in July 2014 by the Moving Picture Experts Group and Video Coding Experts Group. These two extensions enable additional features not covered in the first version of the HEVC standard such as spatial, fidelity, bitdepth, and color gamut scalability, as well as stereoscopic and multiview representations. In this paper, we propose a software parallel decoder architecture for the HEVC standard and its multilayer extensions, including SHVC and MV-HEVC extensions. The decoder consists of multiple instances of the OpenHEVC decoder, one instance to decode each layer with a communication between dependent layers to perform inter-layer predictions. The proposed multilayer HEVC decoder is parallel friendly and supports both wavefront parallelism to simultaneously process adjacent rows of the frame and frame-based parallelism to decode a set of temporal and spatial frames in parallel. Moreover, the most time-consuming operation introduced in the SHVC extension, namely, the resampling of the inter-layer reference picture in spatial scalability, is optimized in single instruction multiple data for x86 platform. We assess the complexity of the multilayer HEVC decoder with respect to the simulcast configuration. The multilayer decoder decoding two SHVC layers introduces in average 40%-71% additional complexity compared with the single layer HEVC decoder. Moreover, the low level optimizations with a hybrid parallel processing solution enable a real-time decoding of 4Kp60 enhancement layer on a 6-core Intel i7 processor running at 3.4 GHz.