encoder.c

X264的纯C语言的的原码

    if( h->i_frame == 0 )
    {
        /* identify ourself */
        x264_nal_start( h, NAL_SEI, NAL_PRIORITY_DISPOSABLE );
        x264_sei_version_write( h, &h->out.bs );
        x264_nal_end( h );

        /* generate sequence parameters */
        x264_nal_start( h, NAL_SPS, NAL_PRIORITY_HIGHEST );
        x264_sps_write( &h->out.bs, h->sps );
        x264_nal_end( h );

        /* generate picture parameters */
        x264_nal_start( h, NAL_PPS, NAL_PRIORITY_HIGHEST );
        x264_pps_write( &h->out.bs, h->pps );
        x264_nal_end( h );
    }
    /* now set output*/
    *pi_nal = h->out.i_nal;
    *pp_nal = &h->out.nal[0];

    return 0;
}


static void x264_frame_put( x264_frame_t *list[X264_BFRAME_MAX], x264_frame_t *frame )
{
    int i = 0;
    while( list[i] ) i++;
    list[i] = frame;
}

static void x264_frame_push( x264_frame_t *list[X264_BFRAME_MAX], x264_frame_t *frame )
{
    int i = 0;
    while( list[i] ) i++;
    while( i-- )
        list[i+1] = list[i];
    list[0] = frame;
}

static x264_frame_t *x264_frame_get( x264_frame_t *list[X264_BFRAME_MAX+1] )
{
    x264_frame_t *frame = list[0];
    int i;
    for( i = 0; list[i]; i++ )
        list[i] = list[i+1];
    return frame;
}

static void x264_frame_sort( x264_frame_t *list[X264_BFRAME_MAX+1], int b_dts )
{
    int i, b_ok;
    do {
        b_ok = 1;
        for( i = 0; list[i+1]; i++ )
        {
            int dtype = list[i]->i_type - list[i+1]->i_type;
            int dtime = list[i]->i_frame - list[i+1]->i_frame;
            int swap = b_dts ? dtype > 0 || ( dtype == 0 && dtime > 0 )
                             : dtime > 0;
            if( swap )
            {
                XCHG( x264_frame_t*, list[i], list[i+1] );
                b_ok = 0;
            }
        }
    } while( !b_ok );
}
#define x264_frame_sort_dts(list) x264_frame_sort(list, 1)
#define x264_frame_sort_pts(list) x264_frame_sort(list, 0)

static inline void x264_reference_build_list( x264_t *h, int i_poc, int i_slice_type )
{
    int i;
    int b_ok;

    /* build ref list 0/1 */
    h->i_ref0 = 0;
    h->i_ref1 = 0;
    for( i = 1; i < h->frames.i_max_dpb; i++ )
    {
        if( h->frames.reference[i]->i_poc >= 0 )
        {
            if( h->frames.reference[i]->i_poc < i_poc )
            {
                h->fref0[h->i_ref0++] = h->frames.reference[i];
            }
            else if( h->frames.reference[i]->i_poc > i_poc )
            {
                h->fref1[h->i_ref1++] = h->frames.reference[i];
            }
        }
    }

    /* Order ref0 from higher to lower poc */
    do
    {
        b_ok = 1;
        for( i = 0; i < h->i_ref0 - 1; i++ )
        {
            if( h->fref0[i]->i_poc < h->fref0[i+1]->i_poc )
            {
                XCHG( x264_frame_t*, h->fref0[i], h->fref0[i+1] );
                b_ok = 0;
                break;
            }
        }
    } while( !b_ok );
    /* Order ref1 from lower to higher poc (bubble sort) for B-frame */
    do
    {
        b_ok = 1;
        for( i = 0; i < h->i_ref1 - 1; i++ )
        {
            if( h->fref1[i]->i_poc > h->fref1[i+1]->i_poc )
            {
                XCHG( x264_frame_t*, h->fref1[i], h->fref1[i+1] );
                b_ok = 0;
                break;
            }
        }
    } while( !b_ok );

    /* In the standard, a P-frame's ref list is sorted by frame_num.
     * We use POC, but check whether explicit reordering is needed */
    h->b_ref_reorder[0] =
    h->b_ref_reorder[1] = 0;
    if( i_slice_type == SLICE_TYPE_P )
    {
        for( i = 0; i < h->i_ref0 - 1; i++ )
            if( h->fref0[i]->i_frame_num < h->fref0[i+1]->i_frame_num )
            {
                h->b_ref_reorder[0] = 1;
                break;
            }
    }

    h->i_ref1 = X264_MIN( h->i_ref1, h->frames.i_max_ref1 );
    h->i_ref0 = X264_MIN( h->i_ref0, h->frames.i_max_ref0 );
    h->i_ref0 = X264_MIN( h->i_ref0, 16 - h->i_ref1 );
}

static inline void x264_fdec_deblock( x264_t *h )
{
    /* apply deblocking filter to the current decoded picture */
    if( !h->sh.i_disable_deblocking_filter_idc )
    {
///        TIMER_START( i_mtime_filter );
        x264_frame_deblocking_filter( h, h->sh.i_type );
 ///       TIMER_STOP( i_mtime_filter );
    }
}

static inline void x264_reference_update( x264_t *h )
{
    int i;

    x264_fdec_deblock( h );

    /* expand border */
    x264_frame_expand_border( h->fdec );

    /* create filtered images */
    x264_frame_filter( h->param.cpu, h->fdec );

    /* expand border of filtered images */
    x264_frame_expand_border_filtered( h->fdec );

    /* move lowres copy of the image to the ref frame */
    for( i = 0; i < 4; i++)
        XCHG( uint8_t*, h->fdec->lowres[i], h->fenc->lowres[i] );

    /* adaptive B decision needs a pointer, since it can't use the ref lists */
    if( h->sh.i_type != SLICE_TYPE_B )
        h->frames.last_nonb = h->fdec;

    /* move frame in the buffer */
    h->fdec = h->frames.reference[h->frames.i_max_dpb-1];
    for( i = h->frames.i_max_dpb-1; i > 0; i-- )
    {
        h->frames.reference[i] = h->frames.reference[i-1];
    }
    h->frames.reference[0] = h->fdec;
}

static inline void x264_reference_reset( x264_t *h )
{
    int i;

    /* reset ref pictures */
    for( i = 1; i < h->frames.i_max_dpb; i++ )
    {
        h->frames.reference[i]->i_poc = -1;
    }
    h->frames.reference[0]->i_poc = 0;
}

static inline void x264_slice_init( x264_t *h, int i_nal_type, int i_slice_type, int i_global_qp )
{
    /* ------------------------ Create slice header  ----------------------- */
    if( i_nal_type == NAL_SLICE_IDR )
    {
        x264_slice_header_init( h, &h->sh, h->sps, h->pps, i_slice_type, h->i_idr_pic_id, h->i_frame_num, i_global_qp );

        /* increment id */
        h->i_idr_pic_id = ( h->i_idr_pic_id + 1 ) % 65536;
    }
    else
    {
        x264_slice_header_init( h, &h->sh, h->sps, h->pps, i_slice_type, -1, h->i_frame_num, i_global_qp );

        /* always set the real higher num of ref frame used */
        h->sh.b_num_ref_idx_override = 1;
        h->sh.i_num_ref_idx_l0_active = h->i_ref0 <= 0 ? 1 : h->i_ref0;
        h->sh.i_num_ref_idx_l1_active = h->i_ref1 <= 0 ? 1 : h->i_ref1;
    }

    h->fdec->i_frame_num = h->sh.i_frame_num;

    if( h->sps->i_poc_type == 0 )
    {
        h->sh.i_poc_lsb = h->fdec->i_poc & ( (1 << h->sps->i_log2_max_poc_lsb) - 1 );
        h->sh.i_delta_poc_bottom = 0;   /* XXX won't work for field */
    }
    else if( h->sps->i_poc_type == 1 )
    {
        /* FIXME TODO FIXME */
    }
    else
    {
        /* Nothing to do ? */
    }

    x264_macroblock_slice_init( h );
}

static int x264_slice_write( x264_t *h )
{
    int i_skip;
    int mb_xy;
    int i;

    /* init stats */
    memset( &h->stat.frame, 0, sizeof(h->stat.frame) );//初始化状态参数
    /* Slice */
    x264_nal_start( h, h->i_nal_type, h->i_nal_ref_idc );//NAL单元开始

    /* Slice header */
    x264_slice_header_write( &h->out.bs, &h->sh, h->i_nal_ref_idc );//写切片头部，一些初始化工作
///    if( h->param.b_cabac )//如果是cabac编码，初始化上下文以及编码器
///    {
        /* alignment needed */
///        bs_align_1( &h->out.bs );

        /* init cabac */
/*        x264_cabac_context_init( &h->cabac, h->sh.i_type, h->sh.i_qp, h->sh.i_cabac_init_idc );
        x264_cabac_encode_init ( &h->cabac, &h->out.bs );
    }*/
    h->mb.i_last_qp = h->sh.i_qp;
    h->mb.i_last_dqp = 0;

    for( mb_xy = h->sh.i_first_mb, i_skip = 0; mb_xy < h->sh.i_last_mb; mb_xy++ )//编码开始，对一个slice中每个宏块进行循环遍历编码，其中const int i_mb_y=mb_xy/h->sps->i_mb_width;和const int i_mb_x=mb_xy%h->sps->i_mb_width;是对宏块位置在slice中的x,y坐标的定位，这个for语句几乎覆盖了整个x264_slices_write()函数
    {
        const int i_mb_y = mb_xy / h->sps->i_mb_width;
        const int i_mb_x = mb_xy % h->sps->i_mb_width;

        int mb_spos = bs_pos(&h->out.bs);

        /* load cache */
        x264_macroblock_cache_load( h, i_mb_x, i_mb_y );//装载缓冲区，它是将要编码的宏块的周围的宏块的值读进来，要想得到当前宏块的预测值，要先知道上面，左面的预测值。

        /* analyse parameters
         * Slice I: choose I_4x4 or I_16x16 mode
         * Slice P: choose between using P mode or intra (4x4 or 16x16)
         * */
///        TIMER_START( i_mtime_analyse );
        x264_macroblock_analyse( h );//分析宏块参数----重点！！通过一系列的SAD算出最优化方案，
///        TIMER_STOP( i_mtime_analyse );

        /* encode this macrobock -> be carefull it can change the mb type to P_SKIP if needed */
///        TIMER_START( i_mtime_encode );
        x264_macroblock_encode( h );//宏块编码，1.判断宏块的类型；2.根据判断的类型进行DCT、量化、ZIGZAG，并记录当前的模式为下次编码宏块（亚宏块）做参考；3.对色度块进行编码，QP限制在0--51之间，选定预测模式；4.求亮度和色度的CBP；5.利用CBP判断要不要SKIP，里面还关系到向量预测。
///        TIMER_STOP( i_mtime_encode );

///        TIMER_START( i_mtime_write );
/*        if( h->param.b_cabac )//是否为cabac编码
        {
            if( mb_xy > h->sh.i_first_mb )
                x264_cabac_encode_terminal( &h->cabac, 0 );

            if( IS_SKIP( h->mb.i_type ) )
                x264_cabac_mb_skip( h, 1 );
            else
            {
                if( h->sh.i_type != SLICE_TYPE_I )
                    x264_cabac_mb_skip( h, 0 );
                x264_macroblock_write_cabac( h, &h->cabac );//若是cabac编码则写入编码cabac
            }
        }
        else
        {*/
            if( IS_SKIP( h->mb.i_type ) )
                i_skip++;
            else
            {
                if( h->sh.i_type != SLICE_TYPE_I )
                {
                    bs_write_ue( &h->out.bs, i_skip );  /* skip run */
                    i_skip = 0;
                }
                x264_macroblock_write_cavlc( h, &h->out.bs );//若不是cabac编码则写入cavlc编码
            }
   ///     }
///        TIMER_STOP( i_mtime_write );

#if VISUALIZE
        if( h->param.b_visualize )
            x264_visualize_mb( h );
#endif

        /* save cache */
        x264_macroblock_cache_save( h );//保存缓冲区数据，以为下次的预测作为参考

        /* accumulate mb stats */
        h->stat.frame.i_mb_count[h->mb.i_type]++;
        if( !IS_SKIP(h->mb.i_type) && !IS_INTRA(h->mb.i_type) && !IS_DIRECT(h->mb.i_type) )
        {
            if( h->mb.i_partition != D_8x8 )
                h->stat.frame.i_mb_count_size[ x264_mb_partition_pixel_table[ h->mb.i_partition ] ] += 4;
            else
                for( i = 0; i < 4; i++ )
                    h->stat.frame.i_mb_count_size[ x264_mb_partition_pixel_table[ h->mb.i_sub_partition[i] ] ] ++;
            if( h->param.i_frame_reference > 1 )
            {
                for( i = 0; i < 4; i++ )
                {
                    int i_ref = h->mb.cache.ref[0][ x264_scan8[4*i] ];
                    if( i_ref >= 0 )
                        h->stat.frame.i_mb_count_ref[i_ref] ++;
                }
            }
        }
        if( h->mb.i_cbp_luma && !IS_INTRA(h->mb.i_type) )
        {
            h->stat.frame.i_mb_count_8x8dct[0] ++;
            h->stat.frame.i_mb_count_8x8dct[1] += h->mb.b_transform_8x8;
        }

        if( h->mb.b_variable_qp )
            x264_ratecontrol_mb(h, bs_pos(&h->out.bs) - mb_spos);
    }

///    if( h->param.b_cabac )