The next generation video coding standard High Efficiency Video Coding (HEVC) provides better compression rate for high resolution videos, at the cost of substantially higher computational complexity. While some latest off-the-shelf consumer electronics support HEVC via ASIC solutions, software implementation of real-time HEVC remains an open challenge for resource-constraint embedded systems. In this work, we present an HEVC decoder design on a low-power embedded heterogeneous multiprocessor System-on-Chip (HMPSoC) with CPU and GPU. Our analysis shows that the massive parallel architecture of GPU leads to a relatively smooth fluctuation on the processing time between video frames. Moreover, the dynamic workload of each frame has a monotonic correlation with a particular coding parameter that can be obtained at decoding time. Based on these observations, we propose an application-specific userspace CPU-GPU DVFS scheme which effectively saves the energy consumption for HEVC decoding. Furthermore, given our accurate workload prediction, only a small frame buffer is required to ensure real-time video decoding.

Hybrid main memory with both DRAM and emerging non-volatile memory (NVM) becomes a promising solution for high performance and energy-efficient embedded systems. Cache plays an important role and highly affects the number of write backs to NVM and DRAM blocks. However, existing cache policies fail to fully address the significant asymmetry between NVM operations (especially writes) and DRAM operations, leading to non-optimal system designs. We propose a write-back aware last-level cache management scheme for the hybrid main memory, which improves the cache hit ratio of NVM memory blocks and minimizes write-backs to NVM. Experimental results show that our proposed framework leads to better performance and energy saving compared with the state-of-the-art cache management scheme for hybrid main memory architecture.