Efficient video resolution adaptation using scalable H.265/HEVC

Dynamically changing the spatial resolution in a video conferencing session is useful for seamlessly adapting the bitrate to changing network conditions and for improving the user experience. Similar to earlier standards, the emerging High Efficiency Video Coding (H.265/HEVC) standard does not allow prediction across different resolutions, so an Instantaneous Decoding Refresh (IDR) picture must be sent to reinitialize the stream when a resolution change happens. IDR pictures take significantly more bits compared to predictively coded pictures. Thus, using them for resolution switching significantly reduces coding efficiency and increases the delay. In this paper we propose a method to support efficient adaptive resolution change using the emerging scalable H.265/HEVC standard. The proposed approach utilizes the inter-layer predicted random access pictures at the enhancement layer for resolution switching, instead of IDR pictures. The experimental results show that when the proposed method was used, the bitrate was reduced at the switching point by 34% on average for the tested video sequences. In addition, visual examples are shown demonstrating the improved visual quality with the proposed method.