x264中的rdo.c函式呼叫關係

x264_rdo_init

• x264_encoder_open

cached_hadamard , cache_satd

• ssd_plane, 1

ssd_plane

• ssd_mb, 3
• x264_rd_cost_chroma, 2
• x264_rd_cost_i4x4, 3
• x264_rd_cost_i8x8, 3
• x264_rd_cost_part, 3
• x264_rd_cost_subpart, 3

x264_rd_cost_subpart:

• x264_rd_cost_part, 1

x264_rd_cost_i8x8

• x264_intra_rd_refine, 1

x264_rd_cost_i4x4:

• x264_intra_rd_refine, 1

x264_rd_cost_chroma:

• x264_intra_rd_refine, 2

上面三個函式都是在同一個函式x264_intra_rd_refine中被呼叫

ssd_mb:

• x264_macroblock_analyse, 1
• x264_rd_cost_mb, 1

在內部被x264_rd_cost_mb呼叫，在檔案外被x264_macroblock_analyse呼叫

x264_rd_cost_part:

• COST_MV_RD, 1
• x264_mb_analyse_p_rd, 1
• x264_me_refine_bidir, 1

外部三次呼叫

x264_rd_cost_mb:

• x264_intra_rd, 3
• x264_intra_rd_refine, 1
• x264_mb_analyse_b_rd, 7
• x264_mb_analyse_inter_p16x16, 1
• x264_mb_analyse_p_rd, 4
• x264_mb_analyse_qp_rd, 5
• x264_mb_analyse_transform_rd, 1
• x264_rd_cost_part, 1

被外部函式23次呼叫

提供給外部呼叫的函式為:
- x264_rdo_init
- x264_rd_cost_i8x8
- x264_rd_cost_i4x4
- x264_rd_cost_chroma
- ssd_mb
- x264_rd_cost_part
- x264_rd_cost_mb

粗體的兩個函式是主要提供給外部的介面，且外部呼叫函式中，除了x264_me_refine_bidir位於me.c，其他都是analyse.c中的函式。

x264_rd_cost_part分析

//這個函式的主要目的是計算在給定量化引數情況下，各種劃分對應的率失真代價
uint64_t x264_rd_cost_part( x264_t *h, int i_lambda2, int i4, int i_pixel )
{

    // i_ssd用來記錄失真，使用的是平方誤差和,i_bits記錄位元速率
    uint64_t i_ssd, i_bits;
    int i8 = i4 >> 2;

    //如果劃分是16*16，直接呼叫x264_rd_cost_mb
    if( i_pixel == PIXEL_16x16 )
    {
        int i_cost = x264_rd_cost_mb( h, i_lambda2 );
        return i_cost;
    }

    //如果劃分比8*8更小，呼叫x264_rd_cost_subpart
    if( i_pixel > PIXEL_8x8 )
        return x264_rd_cost_subpart( h, i_lambda2, i4, i_pixel );

    h->mb.i_cbp_luma = 0;

    //編碼
    x264_macroblock_encode_p8x8( h, i8 );
    if( i_pixel == PIXEL_16x8 )
        x264_macroblock_encode_p8x8( h, i8+1 );
    if( i_pixel == PIXEL_8x16 )
        x264_macroblock_encode_p8x8( h, i8+2 );

    //計算失真
    int ssd_x = 8*(i8&1);
    int ssd_y = 8*(i8>>1);
    i_ssd = ssd_plane( h, i_pixel, 0, ssd_x, ssd_y );
    int chromapix = h->luma2chroma_pixel[i_pixel];
    int chromassd = ssd_plane( h, chromapix, 1, ssd_x>>CHROMA_H_SHIFT, ssd_y>>CHROMA_V_SHIFT )
                  + ssd_plane( h, chromapix, 2, ssd_x>>CHROMA_H_SHIFT, ssd_y>>CHROMA_V_SHIFT );
    i_ssd += ((uint64_t)chromassd * h->mb.i_chroma_lambda2_offset + 128) >> 8;

    //計算位元速率，如果開啟cabac則用cabac，否則使用cavlc，\lamda2是率失真函式中的係數
    if( h->param.b_cabac )
    {
        x264_cabac_t cabac_tmp;
        COPY_CABAC;
        x264_partition_size_cabac( h, &cabac_tmp, i8, i_pixel );
        i_bits = ( (uint64_t)cabac_tmp.f8_bits_encoded * i_lambda2 + 128 ) >> 8;
    }
    else
        i_bits = (uint64_t)x264_partition_size_cavlc( h, i8, i_pixel ) * i_lambda2;

    return (i_ssd<<8) + i_bits;
}

x264_rd_cost_mb分析

static int x264_rd_cost_mb( x264_t *h, int i_lambda2 )
{
    int b_transform_bak = h->mb.b_transform_8x8;
    int i_ssd;
    int i_bits;
    int type_bak = h->mb.i_type;

    //編碼
    x264_macroblock_encode( h );

    if( h->mb.b_deblock_rdo )
        x264_macroblock_deblock( h );

    //計算ssd
    i_ssd = ssd_mb( h );

    //計算位元速率與\lamda2相乘
    if( IS_SKIP( h->mb.i_type ) )
    {
        i_bits = (1 * i_lambda2 + 128) >> 8;
    }
    else if( h->param.b_cabac )
    {
        x264_cabac_t cabac_tmp;
        COPY_CABAC;
        x264_macroblock_size_cabac( h, &cabac_tmp );
        i_bits = ( (uint64_t)cabac_tmp.f8_bits_encoded * i_lambda2 + 32768 ) >> 16;
    }
    else
    {
        x264_macroblock_size_cavlc( h );
        i_bits = ( (uint64_t)h->out.bs.i_bits_encoded * i_lambda2 + 128 ) >> 8;
    }

    h->mb.b_transform_8x8 = b_transform_bak;
    h->mb.i_type = type_bak;

    //返回計算得到的代價與設定的最大代價中較小的那個
    return X264_MIN( i_ssd + i_bits, COST_MAX );
}