今天主要介紹幀內預測一個很重要的函數initAdiPattern，它的主要功能有三個，（1）檢測當前PU的相鄰樣點包括左上、上、右上、左、左下鄰域樣點值的可用性，或者說檢查這些點是否存在；（2）參考樣點的替換過程，主要實現的是JCTVC-J1003即draft
8.4.4.2.2的內容，主要由函數fillReferenceSamples來完成，這個在之前的文章已經討論過了；（3）相鄰樣點即參考樣點的平滑濾波，主要實現draft 8.4.4.2.3的內容。話不多說，下面給出initAdiPattern的實現和我個人的一些註釋，供大家參考。
-
Void TComPattern::initAdiPattern( TComDataCU* pcCU, UInt uiZorderIdxInPart, UInt uiPartDepth, Int* piAdiBuf, Int iOrgBufStride, Int iOrgBufHeight, Bool& bAbove, Bool& bLeft, Bool bLMmode )
-
{//! bLMmode is usually false
-
Pel* piRoiOrigin;
-
Int* piAdiTemp;
-
UInt uiCuWidth = pcCU->getWidth(0) >> uiPartDepth; //!< CU的寬度
-
UInt uiCuHeight = pcCU->getHeight(0)>> uiPartDepth; //!< CU的高度
-
UInt uiCuWidth2 = uiCuWidth<<1;
-
UInt uiCuHeight2 = uiCuHeight<<1;
-
UInt uiWidth;
-
UInt uiHeight;
-
Int iPicStride = pcCU->getPic()->getStride();
-
Int iUnitSize = 0;
-
Int iNumUnitsInCu = 0;
-
Int iTotalUnits = 0;
-
Bool bNeighborFlags[4 * MAX_NUM_SPU_W + 1]; //!< 用於存放4個方向上的相鄰樣點值的可用性, 4 x 32 + 1
-
Int iNumIntraNeighbor = 0; //!< 給可用鄰塊進行計數
-
-
UInt uiPartIdxLT, uiPartIdxRT, uiPartIdxLB;
-
-
//! 獲取當前PU左上角LT，右上角RT以及左下角LB 以4x4塊爲單位的Zorder
-
pcCU->deriveLeftRightTopIdxAdi( uiPartIdxLT, uiPartIdxRT, uiZorderIdxInPart, uiPartDepth );
-
pcCU->deriveLeftBottomIdxAdi ( uiPartIdxLB, uiZorderIdxInPart, uiPartDepth );
-
-
iUnitSize = g_uiMaxCUWidth >> g_uiMaxCUDepth;
-
iNumUnitsInCu = uiCuWidth / iUnitSize;
-
iTotalUnits = (iNumUnitsInCu << 2) + 1; // Top + RightTop + Left + LeftBottom + LeftTop = iNumUnitsInCu + iNumUnitsInCu + iNumUnitsInCu + iNumUnitsInCu + 1
-
//! 掃描順序是從左下到左上，再從左上到右上
-
bNeighborFlags[iNumUnitsInCu*2] = isAboveLeftAvailable( pcCU, uiPartIdxLT );
-
iNumIntraNeighbor += (Int)(bNeighborFlags[iNumUnitsInCu*2]);
-
iNumIntraNeighbor += isAboveAvailable ( pcCU, uiPartIdxLT, uiPartIdxRT, bNeighborFlags+(iNumUnitsInCu*2)+1 );
-
iNumIntraNeighbor += isAboveRightAvailable( pcCU, uiPartIdxLT, uiPartIdxRT, bNeighborFlags+(iNumUnitsInCu*3)+1 );
-
iNumIntraNeighbor += isLeftAvailable ( pcCU, uiPartIdxLT, uiPartIdxLB, bNeighborFlags+(iNumUnitsInCu*2)-1 );
-
iNumIntraNeighbor += isBelowLeftAvailable ( pcCU, uiPartIdxLT, uiPartIdxLB, bNeighborFlags+ iNumUnitsInCu -1 );
-
-
bAbove = true;
-
bLeft = true;
-
-
uiWidth=uiCuWidth2+1;
-
uiHeight=uiCuHeight2+1;
-
-
if (((uiWidth<<2)>iOrgBufStride)||((uiHeight<<2)>iOrgBufHeight))
-
{
-
return;
-
}
-
//! piRoiOrigin指向當前PU左上角
-
piRoiOrigin = pcCU->getPic()->getPicYuvRec()->getLumaAddr(pcCU->getAddr(), pcCU->getZorderIdxInCU()+uiZorderIdxInPart);
-
piAdiTemp = piAdiBuf;
-
-
fillReferenceSamples ( pcCU, piRoiOrigin, piAdiTemp, bNeighborFlags, iNumIntraNeighbor, iUnitSize, iNumUnitsInCu, iTotalUnits, uiCuWidth, uiCuHeight, uiWidth, uiHeight, iPicStride, bLMmode);
-
-
Int i;
-
// generate filtered intra prediction samples
-
Int iBufSize = uiCuHeight2 + uiCuWidth2 + 1; // left and left above border + above and above right border + top left corner = length of 3. filter buffer
-
-
UInt uiWH = uiWidth * uiHeight; // number of elements in one buffer
-
-
//! 下面所進行的工作主要是對參考樣點進行3抽頭的濾波。piAdiBuf指向濾波前的參考樣點的首地址，在濾波前，先將所有參考樣點
-
//! 拷貝到piFilterBuf指向的區域，經濾波後的樣點值保存在piFilterBufN指向的區域，最終將濾波後的樣點值拷貝到piFilterBuf1
-
//! 值得一提的是，最終的結果是，piAdiBuf指向的區域是未經濾波的樣點值，而piFilterBuf1指向的區域是經過濾波的樣點值，
-
//! 兩者的地址相差uiWH = uiWidth * uiHeight = (uiCuWidth2 + 1) * (uiCuHeight2 + 1)，這就解釋了在進行真正的幀內預測時，
-
//! 在需要濾波時，指向piAdiBuf的指針需要加上uiWH的偏移量
-
Int* piFilteredBuf1 = piAdiBuf + uiWH; // 1. filter buffer
-
Int* piFilteredBuf2 = piFilteredBuf1 + uiWH; // 2. filter buffer
-
Int* piFilterBuf = piFilteredBuf2 + uiWH; // buffer for 2. filtering (sequential)
-
Int* piFilterBufN = piFilterBuf + iBufSize; // buffer for 1. filtering (sequential) //!<存放的是參考樣點經3抽頭濾波後的值
-
-
// draft 8.4.4.2.3 Filtering process of neighbouring samples
-
Int l = 0;
-
// left border from bottom to top
-
for (i = 0; i < uiCuHeight2; i++)
-
{
-
piFilterBuf[l++] = piAdiTemp[uiWidth * (uiCuHeight2 - i)]; //!< 左邊界，存儲順序爲從下往上
-
}
-
// top left corner
-
piFilterBuf[l++] = piAdiTemp[0]; //!< 左上邊界
-
// above border from left to right
-
for (i=0; i < uiCuWidth2; i++)
-
{
-
piFilterBuf[l++] = piAdiTemp[1 + i]; //!<上邊界，存儲順序爲從左往右
-
}
-
-
// 1. filtering with [1 2 1]
-
piFilterBufN[0] = piFilterBuf[0]; //!< 第1個點直接保存，不濾波
-
piFilterBufN[iBufSize - 1] = piFilterBuf[iBufSize - 1]; //!< 最後一個點也直接保存，不濾波
-
for (i = 1; i < iBufSize - 1; i++) //!< 對中間樣點值進行3抽頭[1 2 1] / 4 的平滑濾波
-
{
-
piFilterBufN[i] = (piFilterBuf[i - 1] + 2 * piFilterBuf[i]+piFilterBuf[i + 1] + 2) >> 2;
-
}
-
-
// fill 1. filter buffer with filtered values
-
l=0;
-
for (i = 0; i < uiCuHeight2; i++)
-
{
-
piFilteredBuf1[uiWidth * (uiCuHeight2 - i)] = piFilterBufN[l++]; // left border from bottom to top //!< 左邊界
-
}
-
piFilteredBuf1[0] = piFilterBufN[l++]; //!< 左上邊界
-
for (i = 0; i < uiCuWidth2; i++)
-
{
-
piFilteredBuf1[1 + i] = piFilterBufN[l++]; // above border from left to right //!< 上邊界
-
}
-
}
複製代碼
最後附上圖，以幫助大家更好地理解代碼，我就不對圖多作解釋了，相信大家對着代碼能比較容易看明白的。
[img][/img]
（轉載請註明出處。原文地址：http://blog.csdn.net/hevc_cjl/article/details/8184276） |
