Main（int argc，char *argv[]）;

為了方便起見，不妨改寫為：

Main(void){

......

????intargc=5;

????char*argv[]={

???????"main","-o","test.264","foreman.yuv","352x288"???

????};??????

????......

｝

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1.x264_param_default(&param);

這部分設(shè)置編碼參數(shù)的缺省值

附部分變量的意義：

????param->i_csp??????????=X264_CSP_I420; // 設(shè)置輸入的視頻采樣的格式

param->vui.i_sar_width =0;??//VUI:videousability information

????param->i_fps_num???????=10; //幀率

????param->i_fps_den???????=1;??//用兩個(gè)整型的數(shù)的比值，來(lái)表示幀率

?

????

????param->i_frame_reference= 1; //參考幀的最大幀數(shù)。

????param->i_bframe=0;??????????//兩個(gè)參考幀之間的B幀數(shù)目。

???param->b_deblocking_filter = 1; //去塊效應(yīng)相關(guān)

?

???param->b_cabac =0;????????????//cabac的開關(guān)

???param->i_cabac_init_idc = -1;

?

????param->rc.b_cbr=1;???????????//constantbitrate 恒定碼率控制模式

????param->rc.i_bitrate=0;???????//默認(rèn)的碼率

????param->rc.i_rc_buffer_size=0;???//buffer的大小

????param->rc.i_rc_init_buffer=0;???//

param->rc.i_rc_sens =100;???????////整個(gè)param的一個(gè)log文件

?

????

param->analyse.intra = X264_ANALYSE_I4x4 | X264_ANALYSE_I8x8;??

//楨內(nèi)分析

param->analyse.inter = X264_ANALYSE_I4x4 | X264_ANALYSE_I8x8???????????????????????????|X264_ANALYSE_PSUB16x16 |X264_ANALYSE_BSUB16x16;

//楨間分析

param->analyse.i_direct_mv_pred = X264_DIRECT_PRED_SPATIAL;

//預(yù)測(cè)模式

param->analyse.i_me_method = X264_ME_HEX;??????//運(yùn)動(dòng)估計(jì)模式

param->analyse.i_me_range =16;??????????????//運(yùn)動(dòng)估計(jì)范圍

????param->analyse.i_subpel_refine= 5;

????param->analyse.b_chroma_me= 1;

????param->analyse.i_mv_range_thread= -1;

????param->analyse.i_mv_range= -1; // set fromlevel_idc

????param->analyse.i_direct_8x8_inference= -1; // set fromlevel_idc

????param->analyse.i_chroma_qp_offset= 0;

????param->analyse.b_fast_pskip= 1;

????param->analyse.b_dct_decimate= 1;

????param->analyse.i_luma_deadzone[0]= 21;

????param->analyse.i_luma_deadzone[1]= 11;

????param->analyse.b_psnr= 1;

????param->analyse.b_ssim= 1;

?

????param->i_cqm_preset= X264_CQM_FLAT;??//自定義量化矩陣(CQM),初始化量化模式為flat

?

?

2．Parse(argc, argv, &param, &opt ) ;

??解析函數(shù)intc= getopt_long( argc, argv, "8A:B:b:f:hI:i:m:o:p:q:r:t:Vvw",

??long_options, &long_options_index);

??// 得到入口地址的向量與方式的選擇??

??_getopt_internal (argc,argv, optstring, longopts, longind, long_only);??????????????????

??//解析入口地址向量

3．Encode(&param,&opt );

???3.1.x264_encoder_open(param )｛

????……

?????x264_t*h = x264_malloc( sizeof( x264_t ));????//為h分配空間

????

memcpy( &h->param, param, sizeof( x264_param_t ) );

……

3.1.1.x264_validate_parameters(h )；??//驗(yàn)證參數(shù)

?

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????h->sps= &h->sps_array[0];

3.1.2.x264_sps_init(h->sps, h->param.i_sps_id, &h->param );

typedef struct

{

????inti_id;???????//本序列參數(shù)集的id號(hào)

?

????inti_profile_idc;???//指明所用的profile

????inti_level_idc;?????//指明所用的level

?

????intb_constraint_set0;???//其值等于時(shí)，表示必須遵從附錄A.2.1所指明的所有約束條件

????intb_constraint_set1;???//其值等于時(shí)，表示必須遵從附錄A.2.2所指明的所有約束條件

????intb_constraint_set2;???//其值等于時(shí)，表示必須遵從附錄A.2.3所指明的所有約束條件

?

????inti_log2_max_frame_num;???//這個(gè)句法元素只要是為讀取frame_num服務(wù)的

????inti_poc_type;???//指明poc的編碼方法，poc標(biāo)識(shí)圖像的播放順序

????

????inti_log2_max_poc_lsb;???//指明了變量i_poc_lsb的max值

????

????intb_delta_pic_order_always_zero;????//其值為時(shí)，i_delta_poc[0]和i_delta_poc[1]不在片頭出現(xiàn)，并且它們的默認(rèn)值為；當(dāng)本句法元素為時(shí)，上述兩個(gè)句法元素將在片頭出現(xiàn)

????inti_offset_for_non_ref_pic;?????????//用于計(jì)算非參考幀或場(chǎng)的poc

????inti_offset_for_top_to_bottom_field;//用于計(jì)算幀的底場(chǎng)的poc

????inti_num_ref_frames_in_poc_cycle;????//被用來(lái)解碼poc

????inti_offset_for_ref_frame[256];??????//當(dāng)i_poc_type＝時(shí)用于解碼poc，本句法元素對(duì)循環(huán)i_num_ref_frames_in_poc_cycle中的每一個(gè)元素指定一個(gè)偏移

????inti_num_ref_frames;???????//指定參考幀隊(duì)列可能達(dá)到的最大長(zhǎng)度，解碼器根據(jù)這個(gè)句法元素的值開辟存儲(chǔ)區(qū)，這個(gè)存儲(chǔ)區(qū)用于存放已解碼的參考幀

????intb_gaps_in_frame_num_value_allowed;???//這個(gè)句法元素等于時(shí)，表示允許句法元素frame_num可以不連續(xù)；當(dāng)傳輸信道堵塞時(shí)，允許丟棄若干幀

????inti_mb_width;???????//圖像的寬度，以宏塊為單位

????inti_mb_height;??????//圖像的高度，以宏塊為單位

????intb_frame_mbs_only;????//本句法元素等于時(shí)，表示本序列中所有的圖像編碼模式都是幀，沒有其他編碼模式存在；當(dāng)為時(shí)，表示本序列中圖像的編碼模式可能是幀，也可能是場(chǎng)或幀場(chǎng)自適應(yīng)

????intb_mb_adaptive_frame_field;???//指明本序列是否屬于幀場(chǎng)自適應(yīng)模式

????intb_direct8x8_inference;?????//指明b片的直接和skip模式下運(yùn)動(dòng)矢量的預(yù)測(cè)方法

?

????intb_crop;????????//指明解碼器是否要將圖像裁剪后輸出，如果是的話，后面緊跟的四個(gè)句法元素分別指出左、右、上、下裁剪的寬度

????struct

????{

???????inti_left;

???????inti_right;

???????inti_top;

???????inti_bottom;

????}crop;

?

????intb_vui;???//指明vui子結(jié)構(gòu)是否出現(xiàn)在碼流中

????struct

????{

???????......????//省略

?

?

???????

????}vui;

intb_qpprime_y_zero_transform_bypass;

} x264_sps_t;

3.1.3.x264_pps_init(h->pps, h->param.i_sps_id, &h->param, h->sps);

typedef struct

{

????inti_id;??????//本參數(shù)集的序號(hào)，在片頭被引用

????inti_sps_id;??//本圖像參數(shù)集所引用的序列參數(shù)集的序號(hào)

?

????intb_cabac;???//0時(shí)使用cavlc，時(shí)使用cabac

?

????intb_pic_order;??//poc的三種計(jì)算方法在片層還各需要用一些句法元素作為參數(shù)；當(dāng)?shù)扔跁r(shí)，表示在片頭會(huì)有句句法元素指明這些參數(shù)；當(dāng)為時(shí)，表示片頭不會(huì)給出這些參數(shù)

????inti_num_slice_groups;???//圖像中片組的個(gè)數(shù)

?

????inti_num_ref_idx_l0_active;????//指明目前參考幀隊(duì)列的長(zhǎng)度，即有多少各參考幀（短期和長(zhǎng)期），用于list0

????inti_num_ref_idx_l1_active;????//指明目前參考幀隊(duì)列的長(zhǎng)度，即有多少各參考幀（短期和長(zhǎng)期），用于list1

?

????intb_weighted_pred;????????//指明是否允許p和sp片的加權(quán)預(yù)測(cè)

????intb_weighted_bipred;??????//指明是否允許b片的加權(quán)預(yù)測(cè)

?

????inti_pic_init_qp;??????????//亮度分量的量化參數(shù)的初始值

????inti_pic_init_qs;??????????//亮度分量的量化參數(shù)的初始值，用于SP和SI

?

????inti_chroma_qp_index_offset;????//色度分量的量化參數(shù)是根據(jù)亮度分量的量化參數(shù)計(jì)算出來(lái)的，本句法元素用以指明計(jì)算時(shí)用到的參數(shù)

?

????intb_deblocking_filter_control;???//編碼器可以通過(guò)句法元素顯式地控制去塊濾波的強(qiáng)度

????intb_constrained_intra_pred;??????//在p和b片中，幀內(nèi)編碼的宏塊的鄰近宏塊可能是采用的幀間編碼

????intb_redundant_pic_cnt;??????????

????intb_transform_8x8_mode;

?

????inti_cqm_preset;

????constuint8_t *scaling_list[6];

} x264_pps_t;

?

x264_validate_levels(h);??

//3.1.4.x264_cqm_init(x264_t *h )｛

……

h->quant4_mf[i] = x264_malloc(52*size*sizeof(uint16_t) );

????h->dequant4_mf[i]= x264_malloc( 6*size*sizeof(int));

h->unquant4_mf[i] = x264_malloc(52*size*sizeof(int));

……

h->quant4_bias[i] = x264_malloc(52*size*sizeof(uint16_t) );

……

｝

//3.1.4 end

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h->thread[i]= x264_malloc( sizeof(x264_t) );

?

h->thread[i]->fdec = x264_frame_pop_unused( h );

h->thread[i]->out.p_bitstream = x264_malloc( h->out.i_bitstream );

//定義要做nal的那些碼流的地方，i_bitstream是大小，p_bitstream是指針

3.1.5 x264_frame_pop_unused( h)｛

????x264_frame_t*frame;

????if(h->frames.unused[0] )

????????frame= x264_frame_pop( h->frames.unused);??//從unused隊(duì)列中//取出最后位置的一個(gè)楨

????else

????????frame= x264_frame_new( h);????????//分配一幀所需要的空間

????????///3.1.5.1x264_frame_new( h ){

????????……

for( i = 0;i < 3;i++)??????//分配frame的yuv空間，帶邊框

{

inti_divh = 1;

inti_divw = 1;

if( i> 0 )

{

if( h->param.i_csp == X264_CSP_I420 )

i_divh= i_divw = 2;

elseif( h->param.i_csp == X264_CSP_I422 )

i_divw= 2;

}

frame->i_stride[i] = i_stride / i_divw;

frame->i_lines[i] = i_lines / i_divh;

CHECKED_MALLOC( frame->buffer[i],

frame->i_stride[i] * ( frame->i_lines[i] + 2*i_padv / i_divh ) );

?

frame->plane[i]= ((uint8_t*)frame->buffer[i]) +

frame->i_stride[i] * i_padv / i_divh + PADH / i_divw;

//plane指向除去buffer中圖像邊框的yuv真實(shí)數(shù)據(jù)

……

???????}

///3.1.5.1 end

}

????assert(frame->i_reference_count == 0 );

????frame->i_reference_count= 1;

returnframe;

｝

if( x264_macroblock_cache_init( h->thread[i]) < 0 ) returnNULL;

3.1.6．x264_macroblock_cache_init(x264_t *h )｛

//分配x264_t結(jié)構(gòu)體下子結(jié)構(gòu)體mb對(duì)應(yīng)的qp、cbp、skipbp、mb_transform_size、intra4x4_pred_mode、non_zero_count等等在宏塊編碼時(shí)用于控制和傳輸?shù)扔玫降谋?#xff01;

……

CHECKED_MALLOC( h->mb.qp,i_mb_count * sizeof(int8_t) );

????CHECKED_MALLOC(h->mb.cbp,i_mb_count * sizeof(int16_t) );

???CHECKED_MALLOC( h->mb.skipbp, i_mb_count * sizeof(int8_t) );

????CHECKED_MALLOC(h->mb.mb_transform_size, i_mb_count * sizeof(int8_t) );

????

????CHECKED_MALLOC(h->mb.intra4x4_pred_mode, i_mb_count * 7 * sizeof(int8_t) );

????

???CHECKED_MALLOC( h->mb.non_zero_count, i_mb_count * 24 * sizeof(uint8_t) );

????//以4*4塊為單位，24＝4*4＋2*2＋2*2（yuv）

????CHECKED_MALLOC(h->mb.nnz_backup, h->sps->i_mb_width * 4 * 16 * sizeof(uint8_t) );

?

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

????{

????????CHECKED_MALLOC(h->mb.chroma_pred_mode, i_mb_count * sizeof(int8_t) );

????????CHECKED_MALLOC(h->mb.mvd[0], 2*16 * i_mb_count * sizeof(int16_t) );

//mvd[0]指x方向，2*16中的2指前向和后向，16表示mv以4*4為單位

????????CHECKED_MALLOC(h->mb.mvd[1], 2*16 * i_mb_count * sizeof(int16_t) );

????}

?

????for(i=0; i<2; i++ )

????{

????????inti_refs = X264_MIN(16, (i ? 1 : h->param.i_frame_reference) + h->param.b_bframe_pyramid)<< h->param.b_interlaced;

????????for(j=0; j < i_refs; j++ )

????????????CHECKED_MALLOC(h->mb.mvr[i][j], 2* i_mb_count * sizeof(int16_t) );

????}

?

????for(i=0; i<=h->param.b_interlaced; i++ )

????????for(j=0; j<3; j++ )

????????{

????????????CHECKED_MALLOC(h->mb.intra_border_backup[i][j],h->fdec->i_stride[j] );

????????????h->mb.intra_border_backup[i][j]+= 8;

????????}

……

｝

///3.1.6 end

?

3.1.7

if( x264_ratecontrol_new( h ) < 0 ) return NULL;

//碼率控制初始化

?

……

return h;

｝

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