me.c

X264的纯C语言的的原码

            static const int x264_pixel_size_shift[7] = { 0, 1, 1, 2, 3, 3, 4 };

            int ucost1, ucost2;
            int cross_start = 1;

            /* refine predictors */
            ucost1 = bcost;
            DIA1_ITER( pmx, pmy );
            if( pmx || pmy )
                DIA1_ITER( 0, 0 );

            if(i_pixel == PIXEL_4x4)
                goto me_hex2;

            ucost2 = bcost;
            if( (bmx || bmy) && (bmx!=pmx || bmy!=pmy) )
                DIA1_ITER( bmx, bmy );
            if( bcost == ucost2 )
                cross_start = 3;
            omx = bmx; omy = bmy;

            /* early termination */
#define SAD_THRESH(v) ( bcost < ( v >> x264_pixel_size_shift[i_pixel] ) )
            if( bcost == ucost2 && SAD_THRESH(2000) )
            {
                COST_MV_X4( 0,-2, -1,-1, 1,-1, -2,0 );
                COST_MV_X4( 2, 0, -1, 1, 1, 1,  0,2 );
                if( bcost == ucost1 && SAD_THRESH(500) )
                    break;
                if( bcost == ucost2 )
                {
                    int range = (i_me_range>>1) | 1;
                    CROSS( 3, range, range );
                    COST_MV_X4( -1,-2, 1,-2, -2,-1, 2,-1 );
                    COST_MV_X4( -2, 1, 2, 1, -1, 2, 1, 2 );
                    if( bcost == ucost2 )
                        break;
                    cross_start = range + 2;
                }
            }

            /* adaptive search range */
            if( i_mvc )
            {
                /* range multipliers based on casual inspection of some statistics of
                 * average distance between current predictor and final mv found by ESA.
                 * these have not been tuned much by actual encoding. */
                static const int range_mul[4][4] =
                {
                    { 3, 3, 4, 4 },
                    { 3, 4, 4, 4 },
                    { 4, 4, 4, 5 },
                    { 4, 4, 5, 6 },
                };
                int mvd;
                int sad_ctx, mvd_ctx;

                if( i_mvc == 1 )
                {
                    if( i_pixel == PIXEL_16x16 )
                        /* mvc is probably the same as mvp, so the difference isn't meaningful.
                         * but prediction usually isn't too bad, so just use medium range */
                        mvd = 25;
                    else
                        mvd = abs( m->mvp[0] - mvc[0][0] )
                            + abs( m->mvp[1] - mvc[0][1] );
                }
                else
                {
                    /* calculate the degree of agreement between predictors. */
                    /* in 16x16, mvc includes all the neighbors used to make mvp,
                     * so don't count mvp separately. */
                    int i_denom = i_mvc - 1;
                    mvd = 0;
                    if( i_pixel != PIXEL_16x16 )
                    {
                        mvd = abs( m->mvp[0] - mvc[0][0] )
                            + abs( m->mvp[1] - mvc[0][1] );
                        i_denom++;
                    }
                    for( i = 0; i < i_mvc-1; i++ )
                        mvd += abs( mvc[i][0] - mvc[i+1][0] )
                             + abs( mvc[i][1] - mvc[i+1][1] );
                    mvd /= i_denom; //FIXME idiv
                }

                sad_ctx = SAD_THRESH(1000) ? 0
                        : SAD_THRESH(2000) ? 1
                        : SAD_THRESH(4000) ? 2 : 3;
                mvd_ctx = mvd < 10 ? 0
                        : mvd < 20 ? 1
                        : mvd < 40 ? 2 : 3;

                i_me_range = i_me_range * range_mul[mvd_ctx][sad_ctx] / 4;
            }

            /* FIXME if the above DIA2/OCT2/CROSS found a new mv, it has not updated omx/omy.
             * we are still centered on the same place as the DIA2. is this desirable? */
            CROSS( cross_start, i_me_range, i_me_range/2 );

            /* 5x5 ESA */
            omx = bmx; omy = bmy;
            if( bcost != ucost2 )
                COST_MV_X4(  1, 0,  0, 1, -1, 0,  0,-1 );
            COST_MV_X4(  1, 1, -1, 1, -1,-1,  1,-1 );
            COST_MV_X4(  2,-1,  2, 0,  2, 1,  2, 2 );
            COST_MV_X4(  1, 2,  0, 2, -1, 2, -2, 2 );
            COST_MV_X4( -2, 1, -2, 0, -2,-1, -2,-2 );
            COST_MV_X4( -1,-2,  0,-2,  1,-2,  2,-2 );

            /* hexagon grid */
            omx = bmx; omy = bmy;
            for( i = 1; i <= i_me_range/4; i++ )
            {
                static const int hex4[16][2] = {
                    {-4, 2}, {-4, 1}, {-4, 0}, {-4,-1}, {-4,-2},
                    { 4,-2}, { 4,-1}, { 4, 0}, { 4, 1}, { 4, 2},
                    { 2, 3}, { 0, 4}, {-2, 3},
                    {-2,-3}, { 0,-4}, { 2,-3},
                };

                if( 4*i > X264_MIN4( mv_x_max-omx, omx-mv_x_min,
                                     mv_y_max-omy, omy-mv_y_min ) )
                {
                    for( j = 0; j < 16; j++ )
                    {
                        int mx = omx + hex4[j][0]*i;
                        int my = omy + hex4[j][1]*i;
                        if(    mx >= mv_x_min && mx <= mv_x_max
                            && my >= mv_y_min && my <= mv_y_max )
                            COST_MV( mx, my );
                    }
                }
                else
                {
                    COST_MV_X4( -4*i, 2*i, -4*i, 1*i, -4*i, 0*i, -4*i,-1*i );
                    COST_MV_X4( -4*i,-2*i,  4*i,-2*i,  4*i,-1*i,  4*i, 0*i );
                    COST_MV_X4(  4*i, 1*i,  4*i, 2*i,  2*i, 3*i,  0*i, 4*i );
                    COST_MV_X4( -2*i, 3*i, -2*i,-3*i,  0*i,-4*i,  2*i,-3*i );
                }
            }
            goto me_hex2;
        }

    case X264_ME_ESA:
        {
            const int min_x = X264_MAX( bmx - i_me_range, mv_x_min);
            const int min_y = X264_MAX( bmy - i_me_range, mv_y_min);
            const int max_x = X264_MIN( bmx + i_me_range, mv_x_max);
            const int max_y = X264_MIN( bmy + i_me_range, mv_y_max);
            int mx, my;
#if 0
            /* plain old exhaustive search */
            for( my = min_y; my <= max_y; my++ )
                for( mx = min_x; mx <= max_x; mx++ )
                    COST_MV( mx, my );
#else
            /* successive elimination by comparing DC before a full SAD,
             * because sum(abs(diff)) >= abs(diff(sum)). */
            const int stride = m->i_stride[0];
            const int dw = x264_pixel_size[i_pixel].w;
            const int dh = x264_pixel_size[i_pixel].h * stride;
            static uint8_t zero[16*16] = {0,};
            const int enc_dc = h->pixf.sad[i_pixel]( m->p_fenc[0], FENC_STRIDE, zero, 16 );
            const uint16_t *integral_base = &m->integral[ -1 - 1*stride ];

            for( my = min_y; my <= max_y; my++ )
            {
                int mvs[3], i_mvs=0;
                for( mx = min_x; mx <= max_x; mx++ )
                {
                    const uint16_t *integral = &integral_base[ mx + my * stride ];
                    const uint16_t ref_dc = integral[  0 ] + integral[ dh + dw ]
                                          - integral[ dw ] - integral[ dh ];
                    const int bsad = bcost - BITS_MVD(mx,my);
                    if( abs( ref_dc - enc_dc ) < bsad )
                    {
                        if( i_mvs == 3 )
                        {
                            COST_MV_X4_ABS( mvs[0],my, mvs[1],my, mvs[2],my, mx,my );
                            i_mvs = 0;
                        }
                        else
                            mvs[i_mvs++] = mx;
                    }
                }
                for( i=0; i<i_mvs; i++ )
                    COST_MV( mvs[i], my );
            }
#endif
        }
        break;
    }

    /* -> qpel mv */
    if( bpred_cost < bcost )
    {
        m->mv[0] = bpred_mx;
        m->mv[1] = bpred_my;
        m->cost = bpred_cost;
    }
    else
    {
        m->mv[0] = bmx << 2;
        m->mv[1] = bmy << 2;
        m->cost = bcost;
    }

    /* compute the real cost */
    m->cost_mv = p_cost_mvx[ m->mv[0] ] + p_cost_mvy[ m->mv[1] ];
    if( bmx == pmx && bmy == pmy && h->mb.i_subpel_refine < 3 )
        m->cost += m->cost_mv;
    
    /* subpel refine */
    if( h->mb.i_subpel_refine >= 2 )
    {
        int hpel = subpel_iterations[h->mb.i_subpel_refine][2];
        int qpel = subpel_iterations[h->mb.i_subpel_refine][3];
        refine_subpel( h, m, hpel, qpel, p_halfpel_thresh, 0 );
    }
}
#undef COST_MV

void x264_me_refine_qpel( x264_t *h, x264_me_t *m )
{
    int hpel = subpel_iterations[h->mb.i_subpel_refine][0];
    int qpel = subpel_iterations[h->mb.i_subpel_refine][1];

    if( m->i_pixel <= PIXEL_8x8 && h->sh.i_type == SLICE_TYPE_P )
        m->cost -= m->i_ref_cost;
	
    refine_subpel( h, m, hpel, qpel, NULL, 1 );
}

#define COST_MV_SAD( mx, my ) \
{ \
    int stride = 16; \
    uint8_t *src = h->mc.get_ref( m->p_fref, m->i_stride[0], pix[0], &stride, mx, my, bw, bh ); \
    int cost = h->pixf.sad[i_pixel]( m->p_fenc[0], FENC_STRIDE, src, stride ) \
             + p_cost_mvx[ mx ] + p_cost_mvy[ my ]; \
    COPY3_IF_LT( bcost, cost, bmx, mx, bmy, my ); \
}

#define COST_MV_SATD( mx, my, dir ) \
if( b_refine_qpel || (dir^1) != odir ) \
{ \
    int stride = 16; \
    uint8_t *src = h->mc.get_ref( m->p_fref, m->i_stride[0], pix[0], &stride, mx, my, bw, bh ); \
    int cost = h->pixf.mbcmp[i_pixel]( m->p_fenc[0], FENC_STRIDE, src, stride ) \
             + p_cost_mvx[ mx ] + p_cost_mvy[ my ]; \
    if( b_chroma_me && cost < bcost ) \
    { \
        h->mc.mc_chroma( m->p_fref[4], m->i_stride[1], pix[0], 8, mx, my, bw/2, bh/2 ); \
        cost += h->pixf.mbcmp[i_pixel+3]( m->p_fenc[1], FENC_STRIDE, pix[0], 8 ); \
        if( cost < bcost ) \
        { \
            h->mc.mc_chroma( m->p_fref[5], m->i_stride[1], pix[0], 8, mx, my, bw/2, bh/2 ); \
            cost += h->pixf.mbcmp[i_pixel+3]( m->p_fenc[2], FENC_STRIDE, pix[0], 8 ); \
        } \
    } \
    if( cost < bcost ) \
    {                  \
        bcost = cost;  \
        bmx = mx;      \
        bmy = my;      \
        bdir = dir;    \
    } \
}

static void refine_subpel( x264_t *h, x264_me_t *m, int hpel_iters, int qpel_iters, int *p_halfpel_thresh, int b_refine_qpel )
{
    const int bw = x264_pixel_size[m->i_pixel].w;
    const int bh = x264_pixel_size[m->i_pixel].h;
    const int16_t *p_cost_mvx = m->p_cost_mv - m->mvp[0];
    const int16_t *p_cost_mvy = m->p_cost_mv - m->mvp[1];
    const int i_pixel = m->i_pixel;
    const int b_chroma_me = h->mb.b_chroma_me && i_pixel <= PIXEL_8x8;

    DECLARE_ALIGNED( uint8_t, pix[4][16*16], 16 );
    int omx, omy;
    int i;

    int bmx = m->mv[0];
    int bmy = m->mv[1];
    int bcost = m->cost;
    int odir = -1, bdir;


    /* try the subpel component of the predicted mv */
    if( hpel_iters && h->mb.i_subpel_refine < 3 )
    {
        int mx = x264_clip3( m->mvp[0], h->mb.mv_min_spel[0], h->mb.mv_max_spel[0] );
        int my = x264_clip3( m->mvp[1], h->mb.mv_min_spel[1], h->mb.mv_max_spel[1] );
        if( mx != bmx || my != bmy )
            COST_MV_SAD( mx, my );
    }

    /* halfpel diamond search */
    for( i = hpel_iters; i > 0; i-- )
    {
        int omx = bmx, omy = bmy;
        int costs[4];