An adaptive resolution rate control method for intra coding in HEVC

Previous work has shown that spatial resampling can improve rate-distortion performance by providing a higher and more consistent level of video quality at low bitrates. Rate control aims to regulate the video bitrate in accordance to the bit budget. While this is a well studied problem in the single resolution case, very little progress has been made on the adaptive resolution case. In this paper we present an enhanced method of rate control for intra coding that allows the algorithm to learn from previously coded frames and make more accurate predictions, resulting in a lower average mismatch ratio. Our main contribution, however, lies in our adaptive resolution approach where the best scale factor is selected after prediction of the best Quantisation Parameter (QP). We show that our method closely conforms to the bit budget and provides a more stable bitrate. The likelihood of frame skipping is therefore reduced and a more consistent level of video quality is provided compared to standard single resolution methods.