Research On Fast Inter Prediction Algorithm In HEVC Coding Standard

Nowadays more need starts to arise for transmitting high quality and high resolutionvideo contents over communication channels which still entail high cost. In this paper, theH.264/AVC standard, which was developed for more than eight years ago may not be stillthe best to compress such high quality and high resolution video contents under limitedbandwidth for transmission or storage. It motivated ITU-T Video Coding Experts Group(VCEG) and ISO/IEC Moving Picture Experts Group (MPEG) to organize the JointCollaborative Team on Video Coding (JCT-VC) in order to develop a next generation videocoding standard, called High Efficiency Video Coding (HEVC).To achieve high coding efficiency, JCT-VC is developing many new coding tools,among which the generalized hierarchical structure utilizing a quad-tree structure is one ofmost important and effective innovations. Unlike the H.264/AVC only having a codingblock of size16x16as macroblock, it employs a coding tree structure under which a CU, atransform unit (TU) and a prediction unit (PU) can have various block sizes. There are up to35intra prediction modes in HEVC. HEVC adopts a new inter prediction mode: merge mode,both of which make prediction more accurate and promote higher coding efficiency. At thesame time, HEVC adds SAO and ALF after de-blocking filter, which reduce distortionbetween original picture and constructed picture. But adoption of new coding tools arisesmuch higher complexity than H.264/AVC. Some fast algorithm have used CBF flag andSKIP mode to reduce complexity in encoder side.In this paper, considering the relativity between the current encoding frame andreference frames, using the reference frame coding information can effectively direct CUdepth and PU modes in current coding CU. This paper proposes two fast inter algorithms:CU depth early skip algorithm and PU modes early skip algorithm. CU depth early skipalgorithm skips some lower depth with very low probability when coding current CU byusing the depth information of co-located CU. PU modes early skip algorithm skips two interprediction modes:2N×N mode and N×2N mode by using the mode prediction information ofco-located CU to reduce complexity. With the combination of the classic algorithms,this two proposed algorithms can effectively reduce encoding complexity up to78%underupdated HM6.0test model, which promotes the application of HEVC.