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      1 /**
      2  *
      3  * File Name:  armVCM4P10_CompareMotionCostToMV.c
      4  * OpenMAX DL: v1.0.2
      5  * Revision:   9641
      6  * Date:       Thursday, February 7, 2008
      7  *
      8  * (c) Copyright 2007-2008 ARM Limited. All Rights Reserved.
      9  *
     10  *
     11  *
     12  * Description:
     13  * Contains module for comparing motion vectors and SAD's to decide
     14  * the best MV and SAD
     15  *
     16  */
     17 
     18 #include "omxtypes.h"
     19 #include "armOMX.h"
     20 
     21 #include "armVC.h"
     22 #include "armCOMM.h"
     23 
     24 /**
     25  * Function: armVCM4P10_ExpGolBitsUsed
     26  *
     27  * Description:
     28  * Performs calculating Exp-Golomb code length for a given values
     29  *
     30  * Remarks:
     31  *
     32  * Parameters:
     33  * [in]	         val	Signed number for which Exp-Golomb code length has
     34  *                      to be calculated
     35  *
     36  * Return Value:
     37  *             Returns the length of the Exp-Golomb code for val
     38  */
     39 
     40 static OMX_U16 armVCM4P10_ExpGolBitsUsed (OMX_S16 val)
     41 {
     42     OMX_U16 sizeCodeNum, codeNum;
     43 
     44     /* Mapping val to codeNum */
     45     codeNum = armAbs (val);
     46     if (val > 0)
     47     {
     48         codeNum = (2 * codeNum) - 1;
     49     }
     50     else
     51     {
     52         codeNum = 2 * codeNum;
     53     }
     54 
     55     /* Size of the exp-golomb code */
     56     sizeCodeNum = (2 * armLogSize (codeNum + 1)) - 1;
     57 
     58     return sizeCodeNum;
     59 }
     60 
     61 
     62 /**
     63  * Function: armVCM4P10_CompareMotionCostToMV
     64  *
     65  * Description:
     66  * Performs comparision of motion vectors and Motion cost to decide the
     67  * best MV and best MC
     68  *
     69  * Remarks:
     70  *
     71  * Parameters:
     72  * [in]	         mvX	x coordinate of the candidate motion vector in 1/4 pel units
     73  * [in]	         mvY	y coordinate of the candidate motion vector in 1/4 pel units
     74  * [in]	      diffMV	differential MV
     75  * [in]	     candSAD	Candidate SAD
     76  * [in]	      bestMV	Best MV, contains best MV till the previous interation.
     77  * [in]       nLamda    Lamda factor; used to compute motion cost
     78  * [in]   *pBestCost    Contains the current best motion cost.
     79  * [out]  *pBestCost    pBestCost Motion cost will be associated with the best MV
     80  *                      after judgement;
     81  *                      computed as SAD+Lamda*BitsUsedByMV, if the candCost is less
     82  *                      than the best cost passed then the *pBestCost will be equal to candCost
     83  * [out]	  bestMV	Finally will have the best MV after the judgement.
     84  *
     85  * Return Value:
     86  * OMX_INT -- 1 to indicate that the current motion cost is the best
     87  *            0 to indicate that it is NOT the best motion cost
     88  */
     89 
     90 OMX_INT armVCM4P10_CompareMotionCostToMV (
     91     OMX_S16  mvX,
     92     OMX_S16  mvY,
     93     OMXVCMotionVector diffMV,
     94     OMX_INT candSAD,
     95     OMXVCMotionVector *bestMV,
     96     OMX_U32 nLamda,
     97     OMX_S32 *pBestCost
     98 )
     99 {
    100     OMX_S32 candCost;
    101     OMX_U16 sizeCodeNum;
    102 
    103     sizeCodeNum = armVCM4P10_ExpGolBitsUsed (diffMV.dx);
    104     sizeCodeNum += armVCM4P10_ExpGolBitsUsed (diffMV.dy);
    105 
    106     /* Motion cost = SAD +  lamda * ((bitsused(diffMVx) + (bitsused(diffMVy))*/
    107     candCost = candSAD + (nLamda * sizeCodeNum);
    108 
    109     /* Calculate candCost */
    110     if (candCost < *pBestCost)
    111     {
    112         *pBestCost = candCost;
    113         bestMV->dx = mvX;
    114         bestMV->dy = mvY;
    115         return 1;
    116     }
    117     if (candCost > *pBestCost)
    118     {
    119         return 0;
    120     }
    121     /* shorter motion vector */
    122     if ( (mvX * mvX + mvY * mvY) < ((bestMV->dx * bestMV->dx) + (bestMV->dy * bestMV->dy)) )
    123     {
    124         *pBestCost = candCost;
    125         bestMV->dx = mvX;
    126         bestMV->dy = mvY;
    127         return 1;
    128     }
    129 
    130     return 0;
    131 }
    132 
    133 /*End of File*/
    134