//x264_t結構體維護著CODEC的諸多重要信息
struct x264_t
{
??? /* encoder parameters ( 編碼器參數 )*/
??? x264_param_t??? param;

??? x264_t *thread[X264_SLICE_MAX];

??? /* bitstream output ( 字節流輸出 ) */
??? struct
??? {
??????? int???????? i_nal;
??????? x264_nal_t? nal[X264_NAL_MAX];
??????? int???????? i_bitstream;??? /* size of p_bitstream */
??????? uint8_t???? *p_bitstream;?? /* will hold data for all nal */
??????? bs_t??????? bs;
??? } out;

??? /* frame number/poc ( 幀序號 )*/
??? int???????????? i_frame;

??? int???????????? i_frame_offset; /* decoding only */
??? int???????????? i_frame_num;??? /* decoding only */
??? int???????????? i_poc_msb;????? /* decoding only */
??? int???????????? i_poc_lsb;????? /* decoding only */
??? int???????????? i_poc;????????? /* decoding only */

??? int???????????? i_thread_num;?? /* threads only */
??? int???????????? i_nal_type;???? /* threads only */
??? int???????????? i_nal_ref_idc;? /* threads only */

??? /* We use only one SPS(序列參數集) and one PPS(圖像參數集) */
??? x264_sps_t????? sps_array[1];
??? x264_sps_t????? *sps;
??? x264_pps_t????? pps_array[1];
??? x264_pps_t????? *pps;
??? int???????????? i_idr_pic_id;

??? int???????????? (*dequant4_mf[4])[4][4]; /* [4][6][4][4] */
??? int???????????? (*dequant8_mf[2])[8][8]; /* [2][6][8][8] */
??? int???????????? (*quant4_mf[4])[4][4];?? /* [4][6][4][4] */
??? int???????????? (*quant8_mf[2])[8][8];?? /* [2][6][8][8] */
??? int???????????? (*unquant4_mf[4])[16];?? /* [4][52][16] */
??? int???????????? (*unquant8_mf[2])[64];?? /* [2][52][64] */

??? uint32_t??????? nr_residual_sum[2][64];
??? uint32_t??????? nr_offset[2][64];
??? uint32_t??????? nr_count[2];

??? /* Slice header (片頭部) */
??? x264_slice_header_t sh;

??? /* cabac(適應性二元算術編碼) context */
??? x264_cabac_t??? cabac;

??? struct
??? {
??????? /* Frames to be encoded (whose types have been decided(明確的) ) */
??????? x264_frame_t *current[X264_BFRAME_MAX+3];//current是已經準備就緒可以編碼的幀，其類型已經確定
??????? /* Temporary(臨時的) buffer (frames types not yet decided) */
??????? x264_frame_t *next[X264_BFRAME_MAX+3];//next是尚未確定類型的幀
??????? /* 未使用的幀Unused frames */
??????? x264_frame_t *unused[X264_BFRAME_MAX+3];//unused用于回收不使用的frame結構體以備今后再次使用
??????? /* For adaptive(適應的) B decision(決策) */
??????? x264_frame_t *last_nonb;

??????? /* frames used for reference +1 for decoding + sentinels (發射器,標記) */
??????? x264_frame_t *reference[16+2+1+2];

??????? int i_last_idr; /* Frame number of the last IDR (立即刷新圖像) */

??????? int i_input;??? //frames結構體中i_input指示當前輸入的幀的（播放順序）序號。/* Number of input frames already accepted */

??????? int i_max_dpb;? /* Number of frames allocated (分配) in the decoded picture buffer */
??????? int i_max_ref0;
??????? int i_max_ref1;
??????? int i_delay;??? //i_delay設置為由B幀個數（線程個數）確定的幀緩沖延遲，在多線程情況下為i_delay = i_bframe + i_threads - 1。而判斷B幀緩沖填充是否足夠則通過條件判斷：h->frames.i_input <= h->frames.i_delay + 1 - h->param.i_threads。 /* Number of frames buffered for B reordering (重新排序) */
??????? int b_have_lowres;? /* Whether 1/2 resolution (分辨率) luma(亮度) planes(平面) are being used */
??? } frames;//指示和控制幀編碼過程的結構

??? /* current frame being encoded */
??? x264_frame_t??? *fenc;

??? /* frame being reconstructed(重建的) */
??? x264_frame_t??? *fdec;

??? /* references(參考) lists */
??? int???????????? i_ref0;
??? x264_frame_t??? *fref0[16+3];???? /* ref list 0 */
??? int???????????? i_ref1;
??? x264_frame_t??? *fref1[16+3];???? /* ref list 1 */
??? int???????????? b_ref_reorder[2];



??? /* Current MB DCT coeffs(估計系數) */
??? struct
??? {
??????? DECLARE_ALIGNED( int, luma16x16_dc[16], 16 );
??????? DECLARE_ALIGNED( int, chroma_dc[2][4], 16 );
??????? // FIXME merge(合并) with union(結合,并集)
??????? DECLARE_ALIGNED( int, luma8x8[4][64], 16 );
??????? union
??????? {
??????????? DECLARE_ALIGNED( int, residual_ac[15], 16 );
??????????? DECLARE_ALIGNED( int, luma4x4[16], 16 );
??????? } block[16+8];
??? } dct;

??? /* MB table and cache(高速緩沖存儲器) for current frame/mb */
??? struct
??? {
??????? int???? i_mb_count;???????????????? /* number of mbs in a frame */ /* 在一幀中的宏塊中的序號 */

??????? /* Strides (跨,越) */
??????? int???? i_mb_stride;
??????? int???? i_b8_stride;
??????? int???? i_b4_stride;

??????? /* Current index */
??????? int???? i_mb_x;
??????? int???? i_mb_y;
??????? int???? i_mb_xy;
??????? int???? i_b8_xy;
??????? int???? i_b4_xy;
?????? ?
??????? /* Search parameters (搜索參數) */
??????? int???? i_me_method;
??????? int???? i_subpel_refine;
??????? int???? b_chroma_me;
??????? int???? b_trellis;
??????? int???? b_noise_reduction;

??????? /* Allowed qpel(四分之一映像點) MV range to stay (繼續,停留) within the picture + emulated(模擬) edge (邊) pixels */
??????? int???? mv_min[2];
??????? int???? mv_max[2];
??????? /* Subpel MV range for motion search.
???????? * same mv_min/max but includes levels' i_mv_range. */
??????? int???? mv_min_spel[2];
??????? int???? mv_max_spel[2];
??????? /* Fullpel MV range for motion search */
??????? int???? mv_min_fpel[2];
??????? int???? mv_max_fpel[2];

??????? /* neighboring MBs */
??????? unsigned int i_neighbour;
??????? unsigned int i_neighbour8[4];?????? /* neighbours of each 8x8 or 4x4 block that are available */
??????? unsigned int i_neighbour4[16];????? /* at the time the block is coded */
??????? int???? i_mb_type_top;
??????? int???? i_mb_type_left;
??????? int???? i_mb_type_topleft;
??????? int???? i_mb_type_topright;

??????? /* mb table */
??????? int8_t? *type;????????????????????? /* mb type */
??????? int8_t? *qp;??????????????????????? /* mb qp */
??????? int16_t *cbp;?????????????????????? /* mb cbp: 0x0?: luma, 0x?0: chroma, 0x100: luma dc, 0x0200 and 0x0400: chroma dc? (all set for PCM)*/
??????? int8_t? (*intra4x4_pred_mode)[7];?? /* intra4x4 pred mode. for non I4x4 set to I_PRED_4x4_DC(2) */
??????? uint8_t (*non_zero_count)[16+4+4];? /* nzc. for I_PCM set to 16 */
??????? int8_t? *chroma_pred_mode;????????? /* chroma_pred_mode. cabac only. for non intra I_PRED_CHROMA_DC(0) */
??????? int16_t (*mv[2])[2];??????????????? /* mb mv. set to 0 for intra mb */
??????? int16_t (*mvd[2])[2];?????????????? /* mb mv difference with predict. set to 0 if intra. cabac only */
??????? int8_t?? *ref[2];?????????????????? /* mb ref. set to -1 if non used (intra or Lx only) */
??????? int16_t (*mvr[2][16])[2];?????????? /* 16x16 mv for each possible ref */
??????? int8_t? *skipbp;??????????????????? /* block pattern for SKIP or DIRECT (sub)mbs. B-frames + cabac only */
??????? int8_t? *mb_transform_size;???????? /* transform_size_8x8_flag of each mb */

??????? /* current value */
??????? int???? i_type;
??????? int???? i_partition;
??????? int???? i_sub_partition[4];
??????? int???? b_transform_8x8;

??????? int???? i_cbp_luma;
??????? int???? i_cbp_chroma;

??????? int???? i_intra16x16_pred_mode;
??????? int???? i_chroma_pred_mode;

??????? struct
??????? {
??????????? /* space for p_fenc and p_fdec */
#define FENC_STRIDE 16
#define FDEC_STRIDE 32
??????????? DECLARE_ALIGNED( uint8_t, fenc_buf[24*FENC_STRIDE], 16 );
??????????? DECLARE_ALIGNED( uint8_t, fdec_buf[27*FDEC_STRIDE], 16 );

??????????? /* pointer over mb of the frame to be compressed */
??????????? uint8_t *p_fenc[3];

??????????? /* pointer over mb of the frame to be reconstrucated? */
??????????? uint8_t *p_fdec[3];

??????????? /* pointer over mb of the references */
??????????? uint8_t *p_fref[2][16][4+2]; /* last: lN, lH, lV, lHV, cU, cV */
??????????? uint16_t *p_integral[2][16];

??????????? /* fref stride */
??????????? int???? i_stride[3];
??????? } pic;

??????? /* cache */
??????? struct
??????? {
??????????? /* real intra4x4_pred_mode if I_4X4 or I_8X8, I_PRED_4x4_DC if mb available, -1 if not */
??????????? int???? intra4x4_pred_mode[X264_SCAN8_SIZE];

??????????? /* i_non_zero_count if availble else 0x80 */
??????????? int???? non_zero_count[X264_SCAN8_SIZE];

??????????? /* -1 if unused, -2 if unavaible */
??????????? int8_t? ref[2][X264_SCAN8_SIZE];

??????????? /* 0 if non avaible */
??????????? int16_t mv[2][X264_SCAN8_SIZE][2];
??????????? int16_t mvd[2][X264_SCAN8_SIZE][2];

??????????? /* 1 if SKIP or DIRECT. set only for B-frames + CABAC */
??????????? int8_t? skip[X264_SCAN8_SIZE];

??????????? int16_t direct_mv[2][X264_SCAN8_SIZE][2];
??????????? int8_t? direct_ref[2][X264_SCAN8_SIZE];

??????????? /* number of neighbors (top and left) that used 8x8 dct */
??????????? int???? i_neighbour_transform_size;
??????????? int???? b_transform_8x8_allowed;
??????? } cache;

??????? /* */
??????? int???? i_qp;?????? /* current qp */
??????? int???? i_last_qp;? /* last qp */
??????? int???? i_last_dqp; /* last delta qp */
??????? int???? b_variable_qp; /* whether qp is allowed to vary per macroblock */
??????? int???? b_lossless;
??????? int???? b_direct_auto_read; /* take stats for --direct auto from the 2pass log */
??????? int???? b_direct_auto_write; /* analyse direct modes, to use and/or save */

??????? /* B_direct and weighted prediction */
??????? int???? dist_scale_factor[16][16];
??????? int???? bipred_weight[16][16];
??????? /* maps fref1[0]'s ref indices into the current list0 */
??????? int???? map_col_to_list0_buf[2]; // for negative indices
??????? int???? map_col_to_list0[16];
??? } mb;

??? /* rate control encoding only */
??? x264_ratecontrol_t *rc;//struct x264_ratecontrol_t,ratecontrol.c中定義

??? /* stats */
??? struct
??? {
??????? /* Current frame stats */
??????? struct
??????? {
??????????? /* Headers bits (MV+Ref+MB Block Type */
??????????? int i_hdr_bits;
??????????? /* Texture bits (Intra/Predicted) */
??????????? int i_itex_bits;
??????????? int i_ptex_bits;
??????????? /* ? */
??????????? int i_misc_bits;
??????????? /* MB type counts */
??????????? int i_mb_count[19];
??????????? int i_mb_count_i;
??????????? int i_mb_count_p;
??????????? int i_mb_count_skip;
??????????? int i_mb_count_8x8dct[2];//宏塊數_8x8DCT
??????????? int i_mb_count_size[7];
??????????? int i_mb_count_ref[16];
??????????? /* Estimated (SATD) cost as Intra/Predicted frame */
??????????? /* XXX: both omit the cost of MBs coded as P_SKIP */
??????????? int i_intra_cost;
??????????? int i_inter_cost;
??????????? /* Adaptive direct mv pred */
??????????? int i_direct_score[2];
??????? } frame;

??????? /* Cummulated stats */

??????? /* per slice info */
??????? int???? i_slice_count[5];
??????? int64_t i_slice_size[5];
??????? int???? i_slice_qp[5];
??????? /* */
??????? int64_t i_sqe_global[5];
??????? float?? f_psnr_average[5];
??????? float?? f_psnr_mean_y[5];
??????? float?? f_psnr_mean_u[5];
??????? float?? f_psnr_mean_v[5];
??????? /* */
??????? int64_t i_mb_count[5][19];
??????? int64_t i_mb_count_8x8dct[2];
??????? int64_t i_mb_count_size[2][7];
??????? int64_t i_mb_count_ref[2][16];
??????? /* */
??????? int???? i_direct_score[2];
??????? int???? i_direct_frames[2];

??? } stat;

??? /* CPU functions dependants */
??? x264_predict_t????? predict_16x16[4+3];//predict:預測
??? x264_predict_t????? predict_8x8c[4+3];
??? x264_predict8x8_t?? predict_8x8[9+3];
??? x264_predict_t????? predict_4x4[9+3];

??? x264_pixel_function_t pixf;
??? x264_mc_functions_t?? mc;
??? x264_dct_function_t?? dctf;
??? x264_csp_function_t?? csp;//x264_csp_function_t是一個結構體，在common/csp.h中定義
??? x264_quant_function_t quantf;//在common/quant.h中定義
??? x264_deblock_function_t loopf;//在common/frame.h中定義

??? /* vlc table for decoding purpose only */
??? x264_vlc_table_t *x264_coeff_token_lookup[5];
??? x264_vlc_table_t *x264_level_prefix_lookup;
??? x264_vlc_table_t *x264_total_zeros_lookup[15];
??? x264_vlc_table_t *x264_total_zeros_dc_lookup[3];
??? x264_vlc_table_t *x264_run_before_lookup[7];

#if VISUALIZE
??? struct visualize_t *visualize;
#endif
};