Performance, Limitations, and Design Issues of the Integration of a Hardware-Based IME Module With HEVC Video Encoder Software

High Efficiency Video Coding (HEVC) was designed to improve on its predecessor, the H264/AVC standard, by doubling its compression efficiency. As in previous standards, motion estimation is critical for encoders to achieve significant compression gains. However, the cost of accurately removing temporal redundancy in video is prohibitive, especially when encoding very high resolution video sequences. To reduce the overall video encoding time, we have proposed the implementation of an HEVC motion estimation block in hardware, which can achieve significant speed-ups. However, when the IP hardware is integrated into a software platform, there are several constraints and limitations that reduce its impact on the overall encoding time. In this paper, we analyse these issues in detail to identify the main bottlenecks of the overall software/hardware encoding system. From this analysis, we propose a final integration of the hardware motion estimation module with a hardware unit combined with the slice-based parallel version of the HEVC encoding software. The resulting integrated version is able to achieve the best performance in terms of global speed-up, up to 149.63x compared to the sequential version of the HEVC encoder using the full search motion estimation algorithm.