Image segmentation approach for realizing zoomable streaming HEVC video

With the popularity of mobile devices such as mobile phones and cameras, zooming and displaying an arbitrary region of interest (ROI) from a high-resolution video has gained considerable importance. In this study, we implement two methods - partial decoding and tiled encoding - for ROI-based streaming in High Efficiency Video Coding (HEVC). In partial decoding, only the ROI and dependence area are decoded; this approach reduces the calculation cost. In tiled encoding, video frames are split into a grid of tiles, each of which is encoded independently; this approach requires a compatible decoder, and it reduces the streaming bitrate and decoding calculation cost. We evaluated these two methods in terms of the decoding calculation cost, bandwidth efficiency, and video quality. Experimental results show that partial decoding reduced the decoding calculation cost by 35-55%. Tiled encoding showed optimal decoding calculation cost and bandwidth efficiency for a tile size of 128 pixels.