Multi-rate encoding for HEVC-based adaptive HTTP streaming with multiple resolutions

Adaptive HTTP streaming requires a video to be encoded at different rates and qualities called representations. The encoding of multiple representations with the new video coding standard HEVC is computationally complex. In this paper, we propose a multi-rate encoding method which reduces the complexity of encoding a video at multiple spatial resolutions. We first examine block structure similarities at different resolutions and propose a method to derive the block structure for a low resolution representation from a reference high resolution encoding. The derived block structure is used to speed up the encoding of low resolution representations. We further consider the content of the videos in order to achieve a rate-distortion (RD) performance similar to independent HEVC encoding. Experimental results show that the encoding time can be reduced by 50% on average for a low resolution video without degrading the RD performance.