Fast Multi-rate Encoding for Adaptive HTTP Streaming

Adaptive HTTP streaming provides multiple representations of the same content at different bit-rates and resolutions and allows the client to request segments from the available representations in a dynamic, adaptive way depending on its context. The growing number of representations in adaptive HTTP streaming makes encoding of one video segment at different representations a challenging task in terms of encoding time-complexity. In this paper, information of both highest and lowest quality representations are used to limit Rate Distortion Optimization (RDO) process for each Coding Unit Tree (CTU) in High Efficiency Video Coding. Our proposed method first encodes the highest quality representation and consequently uses its information to encode the lowest quality representation. Thereafter, information from both the highest and the lowest quality representations are used to predict features of intermediate quality representations. In particular, the block structure and the selected reference frame of both highest and lowest quality representations are used to predict and shorten the RDO process of each CTU for intermediate quality representations. Our proposed method introduces a delay of two CTUs if parallel encoding is used. Experimental results show significant reduction in time-complexity over the reference software (38%) and the state-of-the-art (10%) while quality degradation is negligible.