[x264-devel] cost calculation of B frames

[Lin Luo]

I am a little confused about the cost calculation of B frames in x264. In
analyse.c,

/* refine qpel */
            else if( i_partition == D_16x16 )
            {
                analysis.l0.me16x16.cost -= analysis.i_lambda *
i_mb_b_cost_table[B_L0_L0];
                analysis.l1.me16x16.cost -= analysis.i_lambda *
i_mb_b_cost_table[B_L1_L1];
                if( i_type == B_L0_L0 )
                {
                    x264_me_refine_qpel( h, &analysis.l0.me16x16 );
                    i_cost = analysis.l0.me16x16.cost
                           + analysis.i_lambda * i_mb_b_cost_table[B_L0_L0];
                }
                else if( i_type == B_L1_L1 )
                {
                    x264_me_refine_qpel( h, &analysis.l1.me16x16 );
                    i_cost = analysis.l1.me16x16.cost
                           + analysis.i_lambda * i_mb_b_cost_table[B_L1_L1];
                }
                else if( i_type == B_BI_BI )
                {
                    x264_me_refine_qpel( h, &analysis.l0.me16x16 );
                    x264_me_refine_qpel( h, &analysis.l1.me16x16 );
                }
            }

Why if i_type is B_BI_BI, the variable i_cost does not update as the case
i_type is B_L0_L0 and B_L1_L1?
Is there any explanation?

Thx, Andy
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