因爲只看了p幀 的預測過程，所以先記錄p幀的，b幀的以後有緣再會。
if( h->sh.i_type == SLICE_TYPE_I )
{
略;
}
else if( h->sh.i_type == SLICE_TYPE_P )
{
int b_skip = 0;
int do_not_try_skip = 0;
h->mc.prefetch_ref( h->mb.pic.p_fref[0][0][h->mb.i_mb_x&3], h->mb.pic.i_stride[0], 0 );
analysis.b_try_skip = 0;
if( analysis.b_force_intra )
{
if( !h->param.analyse.b_psy )
{
x264_mb_analyse_init_qp( h, &analysis, X264_MAX( h->mb.i_qp - h->mb.ip_offset, h->param.rc.i_qp_min ) );
goto intra_analysis;
}
}
else
{
//對skip的mv做限制，如果超過邊界條件，則不嘗試skip模式；
if ((h->mb.cache.pskip_mv[0] & 3) == 0 &&
(h->mb.cache.pskip_mv[1] & 3) == 0)
{
if (h->mb.cache.pskip_mv[0] < h->mb.mv_min[0] || h->mb.cache.pskip_mv[0] > h->mb.mv_max[0])
do_not_try_skip = 1;
if (h->mb.cache.pskip_mv[1] < h->mb.mv_min[1] || h->mb.cache.pskip_mv[1] > h->mb.mv_max[1])
do_not_try_skip = 1;
}
else
{
if (h->mb.cache.pskip_mv[0] < h->mb.mv_min[0] || h->mb.cache.pskip_mv[0] > h->mb.mv_max[0])
do_not_try_skip = 1;
if (h->mb.cache.pskip_mv[1] < h->mb.mv_alert[0] * 4 || h->mb.cache.pskip_mv[1] > h->mb.mv_alert[1] * 4)
do_not_try_skip = 1;
}
/* Special fast-skip logic using information from mb_info. */
if( h->fdec->mb_info && (h->fdec->mb_info[h->mb.i_mb_xy]&X264_MBINFO_CONSTANT) )
{
if(!SLICE_MBAFF && (h->fdec->i_frame - h->fref[0][0]->i_frame) == 1 && !h->sh.b_weighted_pred &&
h->fref[0][0]->effective_qp[h->mb.i_mb_xy] <= h->mb.i_qp && !do_not_try_skip)
{
h->mb.i_partition = D_16x16;
/* Use the P-SKIP MV if we can... */
if( !M32(h->mb.cache.pskip_mv) )
{
b_skip = 1;
h->mb.i_type = P_SKIP;
}
/* Otherwise, just force a 16x16 block. */
else
{
h->mb.i_type = P_L0;
analysis.l0.me16x16.i_ref = 0;
M32( analysis.l0.me16x16.mv ) = 0;
}
goto skip_analysis;
}
/* Reset the information accordingly */
else if( h->param.analyse.b_mb_info_update )
h->fdec->mb_info[h->mb.i_mb_xy] &= ~X264_MBINFO_CONSTANT;
}
int skip_invalid = h->i_thread_frames > 1 && h->mb.cache.pskip_mv[1] > h->mb.mv_max_spel[1];
/* If the current macroblock is off the frame, just skip it. */
if( HAVE_INTERLACED && !MB_INTERLACED && h->mb.i_mb_y * 16 >= h->param.i_height && !skip_invalid )
b_skip = 1;
/* Fast P_SKIP detection */
else if( h->param.analyse.b_fast_pskip )
{
if( skip_invalid )
// FIXME don't need to check this if the reference frame is done
{}
else if(h->param.analyse.i_subpel_refine >= 3)
analysis.b_try_skip = 1;
else if((h->mb.i_mb_type_left[0] == P_SKIP ||
h->mb.i_mb_type_top == P_SKIP ||
h->mb.i_mb_type_topleft == P_SKIP ||
h->mb.i_mb_type_topright == P_SKIP) && !do_not_try_skip)
b_skip = x264_macroblock_probe_pskip( h );//判斷是否是skip塊（通過殘差係數確定);
}
}
h->mc.prefetch_ref( h->mb.pic.p_fref[0][0][h->mb.i_mb_x&3], h->mb.pic.i_stride[0], 1 );
if (do_not_try_skip)
b_skip = 0;
//b_skip = 0;
if( b_skip )
{
h->mb.i_type = P_SKIP;
h->mb.i_partition = D_16x16;
assert( h->mb.cache.pskip_mv[1] <= h->mb.mv_max_spel[1] || h->i_thread_frames == 1 );
skip_analysis:
/* Set up MVs for future predictors */
for( int i = 0; i < h->mb.pic.i_fref[0]; i++ )
M32( h->mb.mvr[0][i][h->mb.i_mb_xy] ) = 0;
}
else //不是skip塊
{
const unsigned int flags = h->param.analyse.inter;
int i_type;
int i_partition;
int i_satd_inter, i_satd_intra;
if (h->param.inter_no_subpart==1)
{
int adaptive_th = 30 * h->mb.i_qp - 500;
h->mb.inter_no_subpart_indicator = (int)(h->fenc->var_per_mb[h->mb.i_mb_xy]) < adaptive_th ? 1 : 0;
}
x264_mb_analyse_load_costs( h, &analysis );
x264_mb_analyse_inter_p16x16( h, &analysis );//先進行16x16的塊預測；
if( h->mb.i_type == P_SKIP )
{
for( int i = 1; i < h->mb.pic.i_fref[0]; i++ )
M32( h->mb.mvr[0][i][h->mb.i_mb_xy] ) = 0;
return;
}
if ((flags & X264_ANALYSE_PSUB16x16) && (h->mb.inter_no_subpart_indicator==0))//進行8x8塊劃分的預測編碼；
{
if( h->param.analyse.b_mixed_references )
x264_mb_analyse_inter_p8x8_mixed_ref( h, &analysis );
else
x264_mb_analyse_inter_p8x8( h, &analysis );
}
/* Select best inter mode */
i_type = P_L0;
i_partition = D_16x16;
i_cost = analysis.l0.me16x16.cost;
if(( flags & X264_ANALYSE_PSUB16x16 ) && (analysis.l0.i_cost8x8 < analysis.l0.me16x16.cost) && (h->mb.inter_no_subpart_indicator == 0))//如果8x8劃分的代價小於16x16的代價，則可以嘗試4x4,4x8,8x4的塊劃分；
{
i_type = P_8x8;
i_partition = D_8x8;
i_cost = analysis.l0.i_cost8x8;
/* Do sub 8x8 */
if(flags & X264_ANALYSE_PSUB8x8 )
{
for( int i = 0; i < 4; i++ )
{
x264_mb_analyse_inter_p4x4( h, &analysis, i );
int i_thresh8x4 = analysis.l0.me4x4[i][1].cost_mv + analysis.l0.me4x4[i][2].cost_mv;
if(1) // !analysis.b_early_terminate || analysis.l0.i_cost4x4[i] < analysis.l0.me8x8[i].cost + i_thresh8x4 )
{
int i_cost8x8 = analysis.l0.i_cost4x4[i];
h->mb.i_sub_partition[i] = D_L0_4x4;
x264_mb_analyse_inter_p8x4( h, &analysis, i );
COPY2_IF_LT( i_cost8x8, analysis.l0.i_cost8x4[i],
h->mb.i_sub_partition[i], D_L0_8x4 );
x264_mb_analyse_inter_p4x8( h, &analysis, i );
COPY2_IF_LT( i_cost8x8, analysis.l0.i_cost4x8[i],
h->mb.i_sub_partition[i], D_L0_4x8 );
i_cost += i_cost8x8 - analysis.l0.me8x8[i].cost;
}
x264_mb_cache_mv_p8x8( h, &analysis, i );
}
analysis.l0.i_cost8x8 = i_cost;
}
}
/* Now do 16x8/8x16 */
//如果8x8塊劃分的代價小於16x16劃分的代價加上兩個8x8塊的mv代價（總的代價=塊的satd/sad+塊的cost_mv）,則可以嘗試8x16和16x8的塊劃分；
int i_thresh16x8 = analysis.l0.me8x8[1].cost_mv + analysis.l0.me8x8[2].cost_mv;
if(( flags & X264_ANALYSE_PSUB16x16 ) && (!analysis.b_early_terminate ||
analysis.l0.i_cost8x8 < analysis.l0.me16x16.cost + i_thresh16x8) && (h->mb.inter_no_subpart_indicator == 0))
{
//i_cost_est16x8[1] 即爲估計的下邊16x8塊的代價，用於16x8塊劃分的快速跳出；
int i_avg_mv_ref_cost = (analysis.l0.me8x8[2].cost_mv + analysis.l0.me8x8[2].i_ref_cost
+ analysis.l0.me8x8[3].cost_mv + analysis.l0.me8x8[3].i_ref_cost + 1) >> 1;
analysis.i_cost_est16x8[1] = analysis.i_satd8x8[0][2] + analysis.i_satd8x8[0][3] + i_avg_mv_ref_cost;
x264_mb_analyse_inter_p16x8( h, &analysis, i_cost );
COPY3_IF_LT( i_cost, analysis.l0.i_cost16x8, i_type, P_L0, i_partition, D_16x8 );
//i_cost_est8x16[1] 即爲估計的右邊16x8塊的代價，用於8x16塊劃分的快速跳出；
i_avg_mv_ref_cost = (analysis.l0.me8x8[1].cost_mv + analysis.l0.me8x8[1].i_ref_cost
+ analysis.l0.me8x8[3].cost_mv + analysis.l0.me8x8[3].i_ref_cost + 1) >> 1;
analysis.i_cost_est8x16[1] = analysis.i_satd8x8[0][1] + analysis.i_satd8x8[0][3] + i_avg_mv_ref_cost;
x264_mb_analyse_inter_p8x16( h, &analysis, i_cost );
COPY3_IF_LT( i_cost, analysis.l0.i_cost8x16, i_type, P_L0, i_partition, D_8x16 );
}
h->mb.i_partition = i_partition;
/* refine qpel */
//FIXME mb_type costs?
//對上述各種劃分中選出的最小代價對應的塊劃分進行運動矢量細化（先是1/2像素，再是1/4像素，需要運動補償）；
if( analysis.i_mbrd || !h->mb.i_subpel_refine )
{
/* refine later */
}
else if( i_partition == D_16x16 )//對16x16塊的mv進行分像素細化；
{
x264_me_refine_qpel( h, &analysis.l0.me16x16 );
i_cost = analysis.l0.me16x16.cost;
}
else if( i_partition == D_16x8 )//對兩個16x8塊的mv進行分像素細化；
{
x264_mb_predict_mv( h, 0, 0, 4, analysis.l0.me16x8[0].mvp );
x264_me_refine_qpel( h, &analysis.l0.me16x8[0] );
x264_macroblock_cache_mv_ptr( h, 0, 0, 4, 2, 0, analysis.l0.me16x8[0].mv );
x264_mb_predict_mv( h, 0, 8, 4, analysis.l0.me16x8[1].mvp );
x264_me_refine_qpel( h, &analysis.l0.me16x8[1] );
x264_macroblock_cache_mv_ptr( h, 0, 2, 4, 2, 0, analysis.l0.me16x8[1].mv );
i_cost = analysis.l0.me16x8[0].cost + analysis.l0.me16x8[1].cost;
}
else if( i_partition == D_8x16 )//對兩個8x16塊的mv進行分像素細化；
{
x264_mb_predict_mv( h, 0, 0, 2, analysis.l0.me8x16[0].mvp );
x264_me_refine_qpel( h, &analysis.l0.me8x16[0] );
x264_macroblock_cache_mv_ptr( h, 0, 0, 2, 4, 0, analysis.l0.me8x16[0].mv );
x264_mb_predict_mv( h, 0, 4, 2, analysis.l0.me8x16[1].mvp );
x264_me_refine_qpel( h, &analysis.l0.me8x16[1] );
x264_macroblock_cache_mv_ptr( h, 2, 0, 2, 4, 0, analysis.l0.me8x16[1].mv );
i_cost = analysis.l0.me8x16[0].cost + analysis.l0.me8x16[1].cost;
}
else if( i_partition == D_8x8 )//對四個8x8塊的mv進行分像素細化；
{
i_cost = 0;
for( int i8x8 = 0; i8x8 < 4; i8x8++ )
{
int x8 = i8x8&1;
int y8 = i8x8>>1;
x264_mb_predict_mv( h, 0, 4*i8x8, 2, analysis.l0.me8x8[i8x8].mvp );
switch( h->mb.i_sub_partition[i8x8] )
{
case D_L0_8x8:
x264_me_refine_qpel( h, &analysis.l0.me8x8[i8x8] );
i_cost += analysis.l0.me8x8[i8x8].cost;
break;
case D_L0_8x4:
x264_me_refine_qpel( h, &analysis.l0.me8x4[i8x8][0] );
x264_me_refine_qpel( h, &analysis.l0.me8x4[i8x8][1] );
i_cost += analysis.l0.me8x4[i8x8][0].cost +
analysis.l0.me8x4[i8x8][1].cost;
break;
case D_L0_4x8:
x264_me_refine_qpel( h, &analysis.l0.me4x8[i8x8][0] );
x264_me_refine_qpel( h, &analysis.l0.me4x8[i8x8][1] );
i_cost += analysis.l0.me4x8[i8x8][0].cost +
analysis.l0.me4x8[i8x8][1].cost;
break;
case D_L0_4x4:
x264_me_refine_qpel( h, &analysis.l0.me4x4[i8x8][0] );
x264_me_refine_qpel( h, &analysis.l0.me4x4[i8x8][1] );
x264_me_refine_qpel( h, &analysis.l0.me4x4[i8x8][2] );
x264_me_refine_qpel( h, &analysis.l0.me4x4[i8x8][3] );
i_cost += analysis.l0.me4x4[i8x8][0].cost +
analysis.l0.me4x4[i8x8][1].cost +
analysis.l0.me4x4[i8x8][2].cost +
analysis.l0.me4x4[i8x8][3].cost;
break;
default:
x264_log( h, X264_LOG_ERROR, "internal error (!8x8 && !4x4)\n" );
break;
}
x264_macroblock_cache_mv_ptr( h, 2*x8, 2*y8, 2, 2, 0, analysis.l0.me8x8[i8x8].mv );
}
}
if( h->mb.b_chroma_me )
{
if( CHROMA444 )
{
x264_mb_analyse_intra( h, &analysis, i_cost );
x264_mb_analyse_intra_chroma( h, &analysis );
}
else
{
x264_mb_analyse_intra_chroma( h, &analysis );
x264_mb_analyse_intra( h, &analysis, i_cost - analysis.i_satd_chroma );
}
analysis.i_satd_i16x16 += analysis.i_satd_chroma;
analysis.i_satd_i8x8 += analysis.i_satd_chroma;
analysis.i_satd_i4x4 += analysis.i_satd_chroma;
}
else //嘗試幀內模式；
x264_mb_analyse_intra( h, &analysis, i_cost );
i_satd_inter = i_cost;
i_satd_intra = X264_MIN3( analysis.i_satd_i16x16,
analysis.i_satd_i8x8,
analysis.i_satd_i4x4 );
if( analysis.i_mbrd )
{
x264_mb_analyse_p_rd( h, &analysis, X264_MIN(i_satd_inter, i_satd_intra) );
i_type = P_L0;
i_partition = D_16x16;
i_cost = analysis.l0.i_rd16x16;
COPY2_IF_LT( i_cost, analysis.l0.i_cost16x8, i_partition, D_16x8 );
COPY2_IF_LT( i_cost, analysis.l0.i_cost8x16, i_partition, D_8x16 );
COPY3_IF_LT( i_cost, analysis.l0.i_cost8x8, i_partition, D_8x8, i_type, P_8x8 );
h->mb.i_type = i_type;
h->mb.i_partition = i_partition;
if( i_cost < COST_MAX )
x264_mb_analyse_transform_rd( h, &analysis, &i_satd_inter, &i_cost );
x264_intra_rd( h, &analysis, i_satd_inter * 5/4 + 1 );
}
//比較幀間各種劃分的cost和幀內模式的cost是，選擇最優的劃分模式；
COPY2_IF_LT( i_cost, analysis.i_satd_i16x16, i_type, I_16x16 );
COPY2_IF_LT( i_cost, analysis.i_satd_i8x8, i_type, I_8x8 );
COPY2_IF_LT( i_cost, analysis.i_satd_i4x4, i_type, I_4x4 );
COPY2_IF_LT( i_cost, analysis.i_satd_pcm, i_type, I_PCM );
h->mb.i_type = i_type;
if( analysis.b_force_intra && !IS_INTRA(i_type) )
{
/* Intra masking: copy fdec to fenc and re-encode the block as intra in order to make it appear as if
* it was an inter block. */
x264_analyse_update_cache( h, &analysis );
x264_macroblock_encode( h );
for( int p = 0; p < (CHROMA444 ? 3 : 1); p++ )
h->mc.copy[PIXEL_16x16]( h->mb.pic.p_fenc[p], FENC_STRIDE, h->mb.pic.p_fdec[p], FDEC_STRIDE, 16 );
if( !CHROMA444 )
{
int height = 16 >> CHROMA_V_SHIFT;
h->mc.copy[PIXEL_8x8] ( h->mb.pic.p_fenc[1], FENC_STRIDE, h->mb.pic.p_fdec[1], FDEC_STRIDE, height );
h->mc.copy[PIXEL_8x8] ( h->mb.pic.p_fenc[2], FENC_STRIDE, h->mb.pic.p_fdec[2], FDEC_STRIDE, height );
}
x264_mb_analyse_init_qp( h, &analysis, X264_MAX( h->mb.i_qp - h->mb.ip_offset, h->param.rc.i_qp_min ) );
goto intra_analysis;
}
if( analysis.i_mbrd >= 2 && h->mb.i_type != I_PCM )
{
if( IS_INTRA( h->mb.i_type ) )
{
x264_intra_rd_refine( h, &analysis );
}
else if( i_partition == D_16x16 )
{
x264_macroblock_cache_ref( h, 0, 0, 4, 4, 0, analysis.l0.me16x16.i_ref );
analysis.l0.me16x16.cost = i_cost;
x264_me_refine_qpel_rd( h, &analysis.l0.me16x16, analysis.i_lambda2, 0, 0 );
}
else if( i_partition == D_16x8 )
{
h->mb.i_sub_partition[0] = h->mb.i_sub_partition[1] =
h->mb.i_sub_partition[2] = h->mb.i_sub_partition[3] = D_L0_8x8;
x264_macroblock_cache_ref( h, 0, 0, 4, 2, 0, analysis.l0.me16x8[0].i_ref );
x264_macroblock_cache_ref( h, 0, 2, 4, 2, 0, analysis.l0.me16x8[1].i_ref );
x264_me_refine_qpel_rd( h, &analysis.l0.me16x8[0], analysis.i_lambda2, 0, 0 );
x264_me_refine_qpel_rd( h, &analysis.l0.me16x8[1], analysis.i_lambda2, 8, 0 );
}
else if( i_partition == D_8x16 )
{
h->mb.i_sub_partition[0] = h->mb.i_sub_partition[1] =
h->mb.i_sub_partition[2] = h->mb.i_sub_partition[3] = D_L0_8x8;
x264_macroblock_cache_ref( h, 0, 0, 2, 4, 0, analysis.l0.me8x16[0].i_ref );
x264_macroblock_cache_ref( h, 2, 0, 2, 4, 0, analysis.l0.me8x16[1].i_ref );
x264_me_refine_qpel_rd( h, &analysis.l0.me8x16[0], analysis.i_lambda2, 0, 0 );
x264_me_refine_qpel_rd( h, &analysis.l0.me8x16[1], analysis.i_lambda2, 4, 0 );
}
else if( i_partition == D_8x8 )
{
x264_analyse_update_cache( h, &analysis );
for( int i8x8 = 0; i8x8 < 4; i8x8++ )
{
if( h->mb.i_sub_partition[i8x8] == D_L0_8x8 )
{
x264_me_refine_qpel_rd( h, &analysis.l0.me8x8[i8x8], analysis.i_lambda2, i8x8*4, 0 );
}
else if( h->mb.i_sub_partition[i8x8] == D_L0_8x4 )
{
x264_me_refine_qpel_rd( h, &analysis.l0.me8x4[i8x8][0], analysis.i_lambda2, i8x8*4+0, 0 );
x264_me_refine_qpel_rd( h, &analysis.l0.me8x4[i8x8][1], analysis.i_lambda2, i8x8*4+2, 0 );
}
else if( h->mb.i_sub_partition[i8x8] == D_L0_4x8 )
{
x264_me_refine_qpel_rd( h, &analysis.l0.me4x8[i8x8][0], analysis.i_lambda2, i8x8*4+0, 0 );
x264_me_refine_qpel_rd( h, &analysis.l0.me4x8[i8x8][1], analysis.i_lambda2, i8x8*4+1, 0 );
}
else if( h->mb.i_sub_partition[i8x8] == D_L0_4x4 )
{
x264_me_refine_qpel_rd( h, &analysis.l0.me4x4[i8x8][0], analysis.i_lambda2, i8x8*4+0, 0 );
x264_me_refine_qpel_rd( h, &analysis.l0.me4x4[i8x8][1], analysis.i_lambda2, i8x8*4+1, 0 );
x264_me_refine_qpel_rd( h, &analysis.l0.me4x4[i8x8][2], analysis.i_lambda2, i8x8*4+2, 0 );
x264_me_refine_qpel_rd( h, &analysis.l0.me4x4[i8x8][3], analysis.i_lambda2, i8x8*4+3, 0 );
}
}
}
}
}
}
else if( h->sh.i_type == SLICE_TYPE_B )
{
略；
}