/*!
***********************************************************************
* \brief
* Brute Force Bipred Sub pixel block motion search
***********************************************************************
*/
distblk // ==> minimum motion cost after search
full_sub_pel_bipred_motion_estimation (Macroblock *currMB, // <-- current Macroblock
MEBlock *mv_block, // <-- motion vector information
int list, // <-- reference picture list
MotionVector *pred_mv1, // <-- motion vector predictor (x) in sub-pel units
MotionVector *pred_mv2, // <-- motion vector predictor (x) in sub-pel units
MotionVector *mv1, // <--> in: search center (x) / out: motion vector (x) - in pel units
MotionVector *mv2, // <--> in: search center (x) / out: motion vector (x) - in pel units
distblk min_mcost, // <-- minimum motion cost (cost for center or huge value)
int* lambda // <-- lagrangian parameter for determining motion cost
)
{
VideoParameters *p_Vid = currMB->p_Vid;
Slice *currSlice = currMB->p_Slice;
int list_offset = p_Vid->mb_data[currMB->mbAddrX].list_offset;
distblk mcost;
int pos, best_pos;
MotionVector cand;
MotionVector cmv, smv = pad_MVs(*mv2, mv_block);
short ref = mv_block->ref_idx;
StorablePicture *ref_picture1 = currSlice->listX[list + list_offset][ref];
StorablePicture *ref_picture2 = currSlice->listX[(list ^ 1) + list_offset][0];
int lambda_factor = lambda[Q_PEL];
// reset distortion. We are always checking all positions to ensure
// distortion computation is done correctly.
//===== loop over search positions =====
for (best_pos = 0, pos = 0; pos < 49; pos++)
{
cand.mv_x = mv1->mv_x + p_Vid->spiral_search[pos].mv_x; // quarter-pel units
cand.mv_y = mv1->mv_y + p_Vid->spiral_search[pos].mv_y; // quarter-pel units
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, pred_mv1);
mcost += mv_cost (p_Vid, lambda_factor, mv2, pred_mv2);
if (mcost >= min_mcost) continue;
cmv = pad_MVs(cand, mv_block);
mcost += mv_block->computeBiPredQPel(ref_picture1, ref_picture2, mv_block, min_mcost - mcost, &cmv, &smv);
if (mcost < min_mcost)
{
min_mcost = mcost;
best_pos = pos;
}
}
if (best_pos)
{
add_mvs(mv1, &p_Vid->spiral_search[best_pos]);
}
//===== return minimum motion cost =====
return min_mcost;
}
/*!
***********************************************************************
* \brief
* Brute Force Sub pixel block motion search
***********************************************************************
*/
distblk // ==> minimum motion cost after search
full_sub_pel_motion_estimation (Macroblock *currMB, // <-- Current Macroblock
MotionVector *pred, // <-- motion vector predictor in sub-pel units
MEBlock *mv_block, // <-- motion estimation structure
distblk min_mcost, // <-- minimum motion cost (cost for center or huge value)
int* lambda // <-- lagrangian parameter for determining motion cost
)
{
Slice *currSlice = currMB->p_Slice;
VideoParameters *p_Vid = currMB->p_Vid;
InputParameters *p_Inp = currMB->p_Inp;
distblk mcost;
int pos, best_pos;
MotionVector cand;
int list = mv_block->list;
int cur_list = list + currMB->list_offset;
short ref = mv_block->ref_idx;
StorablePicture *ref_picture = currSlice->listX[cur_list][ref];
MotionVector *mv = &mv_block->mv[list];
int check_position0 = (!p_Inp->rdopt && currSlice->slice_type != B_SLICE && ref==0 && mv_block->blocktype==1 && mv->mv_x == 0 && mv->mv_y ==0);
MotionVector cmv;
int lambda_factor = lambda[Q_PEL];
// reset distortion. We are always checking all positions to ensure
// distortion computation is done correctly.
min_mcost = DISTBLK_MAX;
//===== loop over all search positions =====
for (best_pos = 0, pos = 0; pos < 49; pos++)
{
cand.mv_x = mv->mv_x + p_Vid->spiral_search[pos].mv_x;
cand.mv_y = mv->mv_y + p_Vid->spiral_search[pos].mv_y;
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, pred);
if (mcost >= min_mcost) continue;
cmv = pad_MVs(cand, mv_block);
mcost += mv_block->computePredQPel( ref_picture, mv_block, min_mcost - mcost, &cmv);
if (pos == 0 && check_position0)
{
mcost -= weighted_cost (lambda_factor, 16);
}
if (mcost < min_mcost)
{
min_mcost = mcost;
best_pos = pos;
}
}
if (best_pos)
{
add_mvs(mv, &p_Vid->spiral_search[best_pos]);
}
//===== return minimum motion cost =====
return min_mcost;
}
/*!
***********************************************************************
* \brief
* Full pixel block motion search
***********************************************************************
*/
distblk // ==> minimum motion cost after search
full_search_motion_estimation (Macroblock *currMB , // <-- current Macroblock
MotionVector *pred_mv, // <-- motion vector predictor in sub-pel units
MEBlock *mv_block, // <-- motion estimation structure
distblk min_mcost, // <-- minimum motion cost (cost for center or huge value)
int lambda_factor // <-- lagrangian parameter for determining motion cost
)
{
VideoParameters *p_Vid = currMB->p_Vid;
InputParameters *p_Inp = currMB->p_Inp;
Slice *currSlice = currMB->p_Slice;
int search_range = imin(mv_block->searchRange.max_x, mv_block->searchRange.max_y)>> 2;
distblk mcost;
int pos;
MotionVector cand, center, pred;
short ref = mv_block->ref_idx;
StorablePicture *ref_picture = currSlice->listX[mv_block->list+currMB->list_offset][ref];
int best_pos = 0; // position with minimum motion cost
int max_pos = (2*search_range+1)*(2*search_range+1); // number of search positions
MotionVector *mv = &mv_block->mv[(short) mv_block->list];
int check_for_00 = (mv_block->blocktype==1 && !p_Inp->rdopt && currSlice->slice_type!=B_SLICE && ref==0);
center.mv_x = mv_block->pos_x_padded + mv->mv_x; // center position x (in sub-pel units)
center.mv_y = mv_block->pos_y_padded + mv->mv_y; // center position y (in sub-pel units)
pred.mv_x = mv_block->pos_x_padded + pred_mv->mv_x; // predicted position x (in sub-pel units)
pred.mv_y = mv_block->pos_y_padded + pred_mv->mv_y; // predicted position y (in sub-pel units)
//===== loop over all search positions =====
for (pos=0; pos<max_pos; pos++)
{
//--- set candidate position (absolute position in sub-pel units) ---
cand.mv_x = center.mv_x + p_Vid->spiral_qpel_search[pos].mv_x;
cand.mv_y = center.mv_y + p_Vid->spiral_qpel_search[pos].mv_y;
//--- initialize motion cost (cost for motion vector) and check ---
mcost = mv_cost (p_Vid, lambda_factor, &cand, &pred);
if (check_for_00 && cand.mv_x == mv_block->pos_x_padded && cand.mv_y == mv_block->pos_y_padded)
{
distblk tmp = weighted_cost (lambda_factor, 16);
mcost = mcost > tmp? (mcost-tmp): 0;
}
if (mcost >= min_mcost) continue;
//--- add residual cost to motion cost ---
mcost += mv_block->computePredFPel(ref_picture, mv_block, min_mcost - mcost, &cand);
//--- check if motion cost is less than minimum cost ---
if (mcost < min_mcost)
{
best_pos = pos;
min_mcost = mcost;
}
}
//===== set best motion vector and return minimum motion cost =====
if (best_pos)
{
add_mvs(mv, &p_Vid->spiral_qpel_search[best_pos]);
}
return min_mcost;
}
/*!
***********************************************************************
* \brief
* Bipred Sub pixel block motion search
***********************************************************************
*/
distblk // ==> minimum motion cost after search
sub_pel_bipred_motion_estimation (Macroblock *currMB, // <-- current Macroblock
MEBlock *mv_block, // <-- motion vector information
int list, // <-- reference picture list
MotionVector *pred_mv1, // <-- motion vector predictor (x) in sub-pel units
MotionVector *pred_mv2, // <-- motion vector predictor (x) in sub-pel units
MotionVector *mv1, // <--> in: search center (x) / out: motion vector (x) - in sub-pel units
MotionVector *mv2, // <--> in: search center (x) / out: motion vector (x) - in sub-pel units
distblk min_mcost, // <-- minimum motion cost (cost for center or huge value)
int* lambda // <-- lagrangian parameter for determining motion cost
)
{
VideoParameters *p_Vid = currMB->p_Vid;
Slice *currSlice = currMB->p_Slice;
int list_offset = p_Vid->mb_data[currMB->mbAddrX].list_offset;
distblk mcost;
int pos, best_pos;
MotionVector cand;
int start_hp = (min_mcost == DISTBLK_MAX) ? 0 : p_Vid->start_me_refinement_hp;
int max_pos2 = ( !p_Vid->start_me_refinement_hp ? imax(1, mv_block->search_pos2) : mv_block->search_pos2);
MotionVector cmv, smv = pad_MVs(*mv2, mv_block);
short ref = mv_block->ref_idx;
StorablePicture *ref_picture1 = currSlice->listX[list + list_offset][ref];
StorablePicture *ref_picture2 = currSlice->listX[(list ^ 1) + list_offset][0];
int lambda_factor = lambda[H_PEL];
/*********************************
***** *****
***** HALF-PEL REFINEMENT *****
***** *****
*********************************/
//===== loop over search positions =====
for (best_pos = 0, pos = start_hp; pos < max_pos2; pos++)
{
cand.mv_x = mv1->mv_x + p_Vid->spiral_hpel_search[pos].mv_x; // quarter-pel units
cand.mv_y = mv1->mv_y + p_Vid->spiral_hpel_search[pos].mv_y; // quarter-pel units
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, pred_mv1);
mcost += mv_cost (p_Vid, lambda_factor, mv2, pred_mv2);
if (mcost >= min_mcost) continue;
cmv = pad_MVs(cand, mv_block);
mcost += mv_block->computeBiPredHPel(ref_picture1, ref_picture2, mv_block, min_mcost - mcost, &cmv, &smv);
if (mcost < min_mcost)
{
min_mcost = mcost;
best_pos = pos;
}
}
if (best_pos)
{
add_mvs(mv1, &p_Vid->spiral_hpel_search[best_pos]);
}
/************************************
***** *****
***** QUARTER-PEL REFINEMENT *****
***** *****
************************************/
if ( !p_Vid->start_me_refinement_qp )
min_mcost = DISTBLK_MAX;
lambda_factor = lambda[Q_PEL];
//===== loop over search positions =====
for (best_pos = 0, pos = p_Vid->start_me_refinement_qp; pos < mv_block->search_pos4; pos++)
{
cand.mv_x = mv1->mv_x + p_Vid->spiral_search[pos].mv_x; // quarter-pel units
cand.mv_y = mv1->mv_y + p_Vid->spiral_search[pos].mv_y; // quarter-pel units
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, pred_mv1);
mcost += mv_cost (p_Vid, lambda_factor, mv2, pred_mv2);
if (mcost >= min_mcost) continue;
cmv = pad_MVs(cand, mv_block);
mcost += mv_block->computeBiPredQPel(ref_picture1, ref_picture2, mv_block, min_mcost - mcost, &cmv, &smv);
if (mcost < min_mcost)
{
min_mcost = mcost;
best_pos = pos;
}
}
if (best_pos)
{
add_mvs(mv1, &p_Vid->spiral_search[best_pos]);
}
//===== return minimum motion cost =====
return min_mcost;
}
/*!
***********************************************************************
* \brief
* Sub pixel block motion search
***********************************************************************
*/
distblk // ==> minimum motion cost after search
sub_pel_motion_estimation (Macroblock *currMB, // <-- Current Macroblock
MotionVector *pred, // <-- motion vector predictor in sub-pel units
MEBlock *mv_block, // <-- motion estimation structure
distblk min_mcost, // <-- minimum motion cost (cost for center or huge value)
int* lambda // <-- lagrangian parameter for determining motion cost
)
{
Slice *currSlice = currMB->p_Slice;
VideoParameters *p_Vid = currMB->p_Vid;
InputParameters *p_Inp = currMB->p_Inp;
distblk mcost;
int pos, best_pos;
MotionVector cand;
int list = mv_block->list;
int cur_list = list + currMB->list_offset;
short ref = mv_block->ref_idx;
StorablePicture *ref_picture = currSlice->listX[cur_list][ref];
MotionVector *mv = &mv_block->mv[list];
int check_position0 = (!p_Inp->rdopt && currSlice->slice_type != B_SLICE && ref==0 && mv_block->blocktype==1 && mv->mv_x == 0 && mv->mv_y ==0);
int max_pos2 = ( !p_Vid->start_me_refinement_hp ? imax(1, mv_block->search_pos2) : mv_block->search_pos2);
MotionVector cmv;
int lambda_factor = lambda[H_PEL];
/*********************************
***** *****
***** HALF-PEL REFINEMENT *****
***** *****
*********************************/
//===== loop over search positions =====
for (best_pos = 0, pos = p_Vid->start_me_refinement_hp; pos < max_pos2; pos++)
{
cand.mv_x = mv->mv_x + p_Vid->spiral_hpel_search[pos].mv_x; // quarter-pel units
cand.mv_y = mv->mv_y + p_Vid->spiral_hpel_search[pos].mv_y; // quarter-pel units
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, pred);
if (mcost >= min_mcost) continue;
cmv = pad_MVs(cand, mv_block);
mcost += mv_block->computePredHPel( ref_picture, mv_block, min_mcost - mcost, &cmv);
if (pos==0 && check_position0)
{
mcost -= weighted_cost (lambda_factor, 16);
}
if (mcost < min_mcost)
{
min_mcost = mcost;
best_pos = pos;
}
}
if (best_pos)
{
mv->mv_x = mv->mv_x + p_Vid->spiral_hpel_search[best_pos].mv_x;
mv->mv_y = mv->mv_y + p_Vid->spiral_hpel_search[best_pos].mv_y;
}
if ( !p_Vid->start_me_refinement_qp )
min_mcost = DISTBLK_MAX;
/************************************
***** *****
***** QUARTER-PEL REFINEMENT *****
***** *****
************************************/
lambda_factor = lambda[Q_PEL];
//===== loop over search positions =====
for (best_pos = 0, pos = p_Vid->start_me_refinement_qp; pos < mv_block->search_pos4; pos++)
{
cand.mv_x = mv->mv_x + p_Vid->spiral_search[pos].mv_x; // quarter-pel units
cand.mv_y = mv->mv_y + p_Vid->spiral_search[pos].mv_y; // quarter-pel units
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, pred);
if (mcost >= min_mcost) continue;
cmv = pad_MVs(cand, mv_block);
mcost += mv_block->computePredQPel( ref_picture, mv_block, min_mcost - mcost, &cmv);
if (mcost < min_mcost)
{
min_mcost = mcost;
best_pos = pos;
}
}
if (best_pos)
{
add_mvs(mv, &p_Vid->spiral_search[best_pos]);
}
//===== return minimum motion cost =====
return min_mcost;
}
/*!
***********************************************************************
* \brief
* Full pixel block motion search
***********************************************************************
*/
distblk // ==> minimum motion cost after search
full_search_bipred_motion_estimation (Macroblock *currMB, // <-- current Macroblock
int list, // <-- reference list
MotionVector *pred_mv1, // <-- motion vector predictor from first list (x|y) in sub-pel units
MotionVector *pred_mv2, // <-- motion vector predictor from second list (x|y) in sub-pel units
MotionVector *mv1, // <--> in: search center (x|y) / out: motion vector (x|y) - in sub-pel units
MotionVector *mv2, // <--> in: search center (x|y)
MEBlock *mv_block, // <-- motion vector information
int search_range, // <-- 1-d search range in sub-pel units
distblk min_mcost, // <-- minimum motion cost (cost for center or huge value)
int lambda_factor // <-- lagrangian parameter for determining motion cost
)
{
Slice *currSlice = currMB->p_Slice;
VideoParameters *p_Vid = currMB->p_Vid;
short ref = mv_block->ref_idx;
StorablePicture *ref_picture1 = currSlice->listX[list + currMB->list_offset][ref];
StorablePicture *ref_picture2 = currSlice->listX[(list ^ 1) + currMB->list_offset][0];
distblk mcost;
int pos;
int best_pos = 0; // position with minimum motion cost
int max_pos = (2 * (search_range >> 2) +1)*(2 * (search_range >> 2) + 1); // number of search positions
MotionVector center1, center2, cand, pred1, pred2;
pred1.mv_x = mv_block->pos_x_padded + pred_mv1->mv_x; // predicted position x (in sub-pel units)
pred1.mv_y = mv_block->pos_y_padded + pred_mv1->mv_y; // predicted position y (in sub-pel units)
pred2.mv_x = mv_block->pos_x_padded + pred_mv2->mv_x; // predicted position x (in sub-pel units)
pred2.mv_y = mv_block->pos_y_padded + pred_mv2->mv_y; // predicted position y (in sub-pel units)
center1.mv_x = mv_block->pos_x_padded + mv1->mv_x; // center position x (in sub-pel units)
center1.mv_y = mv_block->pos_y_padded + mv1->mv_y; // center position y (in sub-pel units)
center2.mv_x = mv_block->pos_x_padded + mv2->mv_x; // center position x of static mv (in sub-pel units)
center2.mv_y = mv_block->pos_y_padded + mv2->mv_y; // center position y of static mv (in sub-pel units)
//===== loop over all search positions =====
for (pos=0; pos<max_pos; pos++)
{
//--- set candidate position (absolute position in sub-pel units) ---
cand.mv_x = center1.mv_x + p_Vid->spiral_qpel_search[pos].mv_x;
cand.mv_y = center1.mv_y + p_Vid->spiral_qpel_search[pos].mv_y;
//--- initialize motion cost (cost for motion vector) and check ---
mcost = mv_cost (p_Vid, lambda_factor, &cand, &pred1);
mcost += mv_cost (p_Vid, lambda_factor, ¢er2, &pred2);
if (mcost >= min_mcost) continue;
//--- add residual cost to motion cost ---
mcost += mv_block->computeBiPredFPel(ref_picture1, ref_picture2, mv_block, min_mcost - mcost,
&cand, ¢er2);
//--- check if motion cost is less than minimum cost ---
if (mcost < min_mcost)
{
best_pos = pos;
min_mcost = mcost;
}
}
//===== set best motion vector and return minimum motion cost =====
if (best_pos)
{
add_mvs(mv1, &p_Vid->spiral_qpel_search[best_pos]);
}
return min_mcost;
}
/*!
***********************************************************************
* \brief
* Fast sub pixel block motion search to support EPZS
***********************************************************************
*/
distblk // ==> minimum motion cost after search
EPZS_sub_pel_motion_estimation ( Macroblock *currMB, // <-- current Macroblock
MotionVector *pred, // <-- motion vector predictor in sub-pel units
MEBlock *mv_block, // <-- motion vector information
distblk min_mcost, // <-- minimum motion cost (cost for center or huge value)
int* lambda // <-- lagrangian parameter for determining motion cost
)
{
VideoParameters *p_Vid = currMB->p_Vid;
Slice *currSlice = currMB->p_Slice;
EPZSParameters *p_EPZS = currSlice->p_EPZS;
int pos, best_pos = 0, second_pos = 0;
distblk mcost;
distblk second_mcost = DISTBLK_MAX;
int max_pos2 = ( (!p_Vid->start_me_refinement_hp || !p_Vid->start_me_refinement_qp) ? imax(1, mv_block->search_pos2) : mv_block->search_pos2);
int list = mv_block->list;
int cur_list = list + currMB->list_offset;
short ref = mv_block->ref_idx;
StorablePicture *ref_picture = currSlice->listX[cur_list][ref];
MotionVector *mv = &mv_block->mv[list];
MotionVector cand;
MotionVector padded_mv = pad_MVs (*mv, mv_block);
MotionVector pred_mv = pad_MVs (*pred, mv_block);
int start_pos = 5, end_pos = max_pos2;
int lambda_factor = lambda[H_PEL];
distblk lambda_dist = weighted_cost(lambda_factor, 2);
distblk sub_threshold = p_EPZS->subthres[mv_block->blocktype] + lambda_dist;
/*********************************
***** *****
***** HALF-PEL REFINEMENT *****
***** *****
*********************************/
//===== loop over search positions =====
for (best_pos = 0, pos = p_Vid->start_me_refinement_hp; pos < imin(5, max_pos2); ++pos)
{
cand = add_MVs(search_point_hp[pos], &padded_mv);
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, &pred_mv);
if (mcost < second_mcost)
{
mcost += mv_block->computePredHPel(ref_picture, mv_block, second_mcost - mcost, &cand);
if (mcost < min_mcost)
{
second_mcost = min_mcost;
second_pos = best_pos;
min_mcost = mcost;
best_pos = pos;
}
else if (mcost < second_mcost)
{
second_mcost = mcost;
second_pos = pos;
}
}
}
if (best_pos ==0 && (pred->mv_x == mv->mv_x) && (pred->mv_y == mv->mv_y) && min_mcost < sub_threshold)
{
return min_mcost;
}
if(mv_block->search_pos2 >= 9)
{
if (best_pos !=0 || (iabs(pred->mv_x - mv->mv_x) + iabs(pred->mv_y - mv->mv_y)))
{
start_pos = next_start_pos[best_pos][second_pos];
end_pos = next_end_pos[best_pos][second_pos];
for (pos = start_pos; pos < end_pos; ++pos)
{
cand = add_MVs(search_point_hp[pos], &padded_mv);
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, &pred_mv);
if (mcost < min_mcost)
{
mcost += mv_block->computePredHPel( ref_picture, mv_block, min_mcost - mcost, &cand);
if (mcost < min_mcost)
{
min_mcost = mcost;
best_pos = pos;
}
}
}
}
}
if (best_pos)
{
add_mvs(mv, &search_point_hp[best_pos]);
padded_mv = pad_MVs (*mv, mv_block);
}
/************************************
***** *****
***** QUARTER-PEL REFINEMENT *****
***** *****
************************************/
end_pos = (min_mcost < sub_threshold) ? 1 : 5;
second_mcost = DISTBLK_MAX;
if ( !p_Vid->start_me_refinement_qp )
{
best_pos = -1;
min_mcost = DISTBLK_MAX;
}
else
{
best_pos = 0;
}
lambda_factor = lambda[Q_PEL];
//===== loop over search positions =====
for (pos = p_Vid->start_me_refinement_qp; pos < end_pos; ++pos)
{
cand = add_MVs(search_point_qp[pos], &padded_mv);
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, &pred_mv);
if (mcost < second_mcost)
{
mcost += mv_block->computePredQPel(ref_picture, mv_block, second_mcost - mcost, &cand);
if (mcost < min_mcost)
{
second_mcost = min_mcost;
second_pos = best_pos;
min_mcost = mcost;
best_pos = pos;
}
else if (mcost < second_mcost)
{
second_mcost = mcost;
second_pos = pos;
}
}
}
//if (best_pos ==0 && (pred->mv_x == mv->mv_x) && (pred->mv_y == mv->mv_y) && min_mcost < sub_threshold)
if ( (min_mcost > sub_threshold))
{
if (best_pos !=0 || (iabs(pred->mv_x - mv->mv_x) + iabs(pred->mv_y - mv->mv_y)))
{
start_pos = next_start_pos[best_pos][second_pos];
end_pos = next_end_pos[best_pos][second_pos];
for (pos = start_pos; pos < end_pos; ++pos)
{
cand = add_MVs(search_point_qp[pos], &padded_mv);
//----- set motion vector cost -----
mcost = mv_cost (p_Vid, lambda_factor, &cand, &pred_mv);
if (mcost < min_mcost)
{
mcost += mv_block->computePredQPel(ref_picture, mv_block, min_mcost - mcost, &cand);
if (mcost < min_mcost)
{
min_mcost = mcost;
best_pos = pos;
}
}
}
}
}
if (best_pos)
{
add_mvs(mv, &search_point_qp[best_pos]);
}
//===== return minimum motion cost =====
return min_mcost;
}