HEVC inter-Frame Prediction 2 -- Analysis of TComDataCU: xGetColMVP

This document analyzes this function in detail: [cpp] Bool TComDataCU: xGetColMVP (RefPicList eRefPicList, Int uiCUAddr, Int uiPartUnitIdx, TComMv & RMV, Int & riRefIdx ){//! For more information, see draft 8.5.2.1.7, Derivation process for temporal luma motion vector prediction //! For The return conditions of this function, refer to The 3rd dots in this section. The variables mvLXCol and availableFlagLXCol are derived as follows... UInt uiAbsPartAddr = uiPartUnitIdx; RefPicList eColRefPicList; Int iColPOC, iColRefPOC, iCurrPOC, iCurrRefPOC, iScale; TComMv cColMv; // use coldir. //! Colocated Picture TComPic * pColPic = getSlice ()-> getRefPic (RefPicList (getSlice ()-> isInterB ()? 1-getSlice ()-> getColFromL0Flag (): 0), getSlice ()-> getColRefIdx ());//! Colocated CU TComDataCU * pColCU = pColPic-> getCU (uiCUAddr); if (pColCU-> getPic () = 0 | pColCU-> getPartitionSize (uiPartUnitIdx) = SIZE_NONE) //! <Colocated Picture or colocated CU does not exist {return false;} iCurrPOC = m_pcSlice-> getPOC ();//! <Current slice POC iCurrRefPOC = m_pcSlice-> getRefPic (eRefPicList, riRefIdx)-> getPOC ();//! <Current slice reference frame POC iColPOC = pColCU-> getSlice ()-> getPOC ();//! <Current slice's colocated picuture POC if (pColCU-> isIntra (uiAbsPartAddr ))//! <Colocated CU is in intra-frame prediction mode, that is, if no MV is available, false {return false;} eColRefPicList = getSlice ()-> getCheckLDC ()? ERefPicList: RefPicList (getSlice ()-> response (); Int iColRefIdx = pColCU-> getCUMvField (RefPicList (eColRefPicList)-> getRefIdx (response );//! <Colocated CU's reference frame sequence number if (iColRefIdx <0) {eColRefPicList = RefPicList (1-eColRefPicList); iColRefIdx = pColCU-> getCUMvField (RefPicList (Records )) -> getRefIdx (uiAbsPartAddr); if (iColRefIdx <0) {return false ;}// Scale the vector. iColRefPOC = pColCU-> getSlice ()-> getRefPOC (eColRefPicList, iColRefIdx); cColMv = pColCU-> getCUMvField (eColRefPicList)-> getMv (response); response = M_pcSlice-> getRefPic (eRefPicList, riRefIdx)-> getPOC (); Bool bIsCurrRefLongTerm = m_pcserver-> getRefPic (eRefPicList, riRefIdx)-> getIsLongTerm (); bool bIsColRefLongTerm = pColCU-> getSlice ()-> getRefPic (eColRefPicList, iColRefIdx)-> getIsUsedAsLongTerm (); if (bIsCurrRefLongTerm! = BIsColRefLongTerm) {return false;} if (bIsCurrRefLongTerm | bIsColRefLongTerm) {RMV = cColMv ;//! <Draft formula (8-155)} else {iScale = xGetDistScaleFactor (iCurrPOC, iCurrRefPOC, iColPOC, iColRefPOC );//! <Next, analyze if (iScale = 4096) {RMV = cColMv;} else {RMV = cColMv. scaleMv (iScale );//! <Draft formula (8-158)} return true;} [cpp] Int TComDataCU: xGetDistScaleFactor (Int iCurrPOC, Int iCurrRefPOC, Int iColPOC, Int iColRefPOC) {Int iDiffPocD = iColPOC-iColRefPOC ;//! <Draft formula (8-159) Int iDiffPocB = iCurrPOC-iCurrRefPOC ;//! <Draft formula (8-160) if (iDiffPocD = iDiffPocB) {return 4096;} else {www.2cto.com Int iTDB = Clip3 (-128,127, iDiffPocB ); int iTDD = Clip3 (-128,127, iDiffPocD); Int iX = (0x4000 + abs (iTDD/2)/iTDD ;//! <Draft formula (8-156) Int iScale = Clip3 (-4096,409 5, (iTDB * iX + 32)> 6 );//! <Draft formula (8-157) return iScale;} [cpp] const TComMv scaleMv (Int iScale) const {//! Draft formula (8-158) Int mvx = Clip3 (-32768,327 67, (iScale * getHor () + 127 + (iScale * getHor () <0)> 8 ); int mvy = Clip3 (-32768,327 67, (iScale * getVer () + 127 + (iScale * getVer () <0)> 8); return TComMv (mvx, mvy );}