A computationally scalable fast intra coding scheme for HEVC video encoder

Abstract

The High Efficiency Video Coding (HEVC) adopts 35 intra prediction modes to provide a more precise intra prediction. As a result, HEVC intra coding is much more complex. To provide a flexible solution for battery-powered devices, which include varying power budgets based on battery level, this paper jointly employs statistical distribution of different intra modes, and texture analysis. While the statistical information specifies the most efficient modes for extremely low power budgets, for moderate to high power budgets the best angular modes are predicted by analyzing the residual of the Planar mode, which is demonstrated to represent the dominant edges of the block. Moreover, a scheme is presented that further reduces the complexity by predicting the more important DC and Planar modes using the information provided by the entropy coder. The proposed method imposes almost no computational overhead since it utilizes the existing internal operators of HEVC. Ultimately, an intra prediction scheme with seven predefined levels of complexity is presented that provides coding for various power budgets and devices with various capabilities. The highest level of this scheme provides ~23% total encoding time reduction compared to HM, in all-intra configuration, with only 0.78% penalty on BD-Rate for high end devices. While the lowest level makes encoding possible for extremely low power devices and low battery plans with ~52% time reduction (almost the entire share of intra coding) at the cost of 9.6% BD-Rate, which is shown to be nearly minimal for this level of processing power.