// Function will arrange the long-term pictures in the decreasing order of poc_lsb_lt,
// and among the pictures with the same lsb, it arranges them in increasing delta_poc_msb_cycle_lt value
void DPB::arrangeLongtermPicturesInRPS(TComSlice *slice)
{
TComReferencePictureSet *rps = slice->getRPS();
if (!rps->getNumberOfLongtermPictures())
{
return;
}
// Arrange long-term reference pictures in the correct order of LSB and MSB,
// and assign values for pocLSBLT and MSB present flag
int longtermPicsPoc[MAX_NUM_REF_PICS], longtermPicsLSB[MAX_NUM_REF_PICS], indices[MAX_NUM_REF_PICS];
int longtermPicsMSB[MAX_NUM_REF_PICS];
bool mSBPresentFlag[MAX_NUM_REF_PICS];
::memset(longtermPicsPoc, 0, sizeof(longtermPicsPoc)); // Store POC values of LTRP
::memset(longtermPicsLSB, 0, sizeof(longtermPicsLSB)); // Store POC LSB values of LTRP
::memset(longtermPicsMSB, 0, sizeof(longtermPicsMSB)); // Store POC LSB values of LTRP
::memset(indices, 0, sizeof(indices)); // Indices to aid in tracking sorted LTRPs
::memset(mSBPresentFlag, 0, sizeof(mSBPresentFlag)); // Indicate if MSB needs to be present
// Get the long-term reference pictures
int offset = rps->getNumberOfNegativePictures() + rps->getNumberOfPositivePictures();
int i, ctr = 0;
int maxPicOrderCntLSB = 1 << slice->getSPS()->getBitsForPOC();
for (i = rps->getNumberOfPictures() - 1; i >= offset; i--, ctr++)
{
longtermPicsPoc[ctr] = rps->getPOC(i); // LTRP POC
longtermPicsLSB[ctr] = getLSB(longtermPicsPoc[ctr], maxPicOrderCntLSB); // LTRP POC LSB
indices[ctr] = i;
longtermPicsMSB[ctr] = longtermPicsPoc[ctr] - longtermPicsLSB[ctr];
}
int numLongPics = rps->getNumberOfLongtermPictures();
assert(ctr == numLongPics);
// Arrange pictures in decreasing order of MSB;
for (i = 0; i < numLongPics; i++)
{
for (int j = 0; j < numLongPics - 1; j++)
{
if (longtermPicsMSB[j] < longtermPicsMSB[j + 1])
{
std::swap(longtermPicsPoc[j], longtermPicsPoc[j + 1]);
std::swap(longtermPicsLSB[j], longtermPicsLSB[j + 1]);
std::swap(longtermPicsMSB[j], longtermPicsMSB[j + 1]);
std::swap(indices[j], indices[j + 1]);
}
}
}
for (i = 0; i < numLongPics; i++)
{
// Check if MSB present flag should be enabled.
// Check if the buffer contains any pictures that have the same LSB.
TComPic* iterPic = m_picList.first();
while (iterPic)
{
if ((getLSB(iterPic->getPOC(), maxPicOrderCntLSB) == longtermPicsLSB[i]) && // Same LSB
(iterPic->getSlice()->isReferenced()) && // Reference picture
(iterPic->getPOC() != longtermPicsPoc[i])) // Not the LTRP itself
{
mSBPresentFlag[i] = true;
break;
}
iterPic = iterPic->m_next;
}
}
// tempArray for usedByCurr flag
bool tempArray[MAX_NUM_REF_PICS];
::memset(tempArray, 0, sizeof(tempArray));
for (i = 0; i < numLongPics; i++)
{
tempArray[i] = rps->getUsed(indices[i]) ? true : false;
}
// Now write the final values;
ctr = 0;
int currMSB = 0, currLSB = 0;
// currPicPoc = currMSB + currLSB
currLSB = getLSB(slice->getPOC(), maxPicOrderCntLSB);
currMSB = slice->getPOC() - currLSB;
for (i = rps->getNumberOfPictures() - 1; i >= offset; i--, ctr++)
{
rps->setPOC(i, longtermPicsPoc[ctr]);
rps->setDeltaPOC(i, -slice->getPOC() + longtermPicsPoc[ctr]);
rps->setUsed(i, tempArray[ctr]);
rps->setPocLSBLT(i, longtermPicsLSB[ctr]);
rps->setDeltaPocMSBCycleLT(i, (currMSB - (longtermPicsPoc[ctr] - longtermPicsLSB[ctr])) / maxPicOrderCntLSB);
rps->setDeltaPocMSBPresentFlag(i, mSBPresentFlag[ctr]);
assert(rps->getDeltaPocMSBCycleLT(i) >= 0); // Non-negative value
}
for (i = rps->getNumberOfPictures() - 1, ctr = 1; i >= offset; i--, ctr++)
{
for (int j = rps->getNumberOfPictures() - 1 - ctr; j >= offset; j--)
{
// Here at the encoder we know that we have set the full POC value for the LTRPs, hence we
// don't have to check the MSB present flag values for this constraint.
assert(rps->getPOC(i) != rps->getPOC(j)); // If assert fails, LTRP entry repeated in RPS!!!
}
}
}
