Accelerating HEVC transcoder by exploiting decoded quadtree

This paper proposes an accelerated High-Efficiency Video Coding (HEVC) transcoder which can promptly provide downscaled video contents to various devices. The quadtree information is first extracted from the decoding process and is transformed for the target resolution. By utilizing the decoded depth information, the encoder can be accelerated by only searching the optimal depths in the quadtree, without losing the video quality. The encoder also adaptively changes the depth search ranges according to the picture order count (POC) for further optimization. Our proposed method shows a maximum encoding speedup of 2.18, with only 0.3% BD-rate increase in the best case.