一段H264数据的分析

H264的数据流分为两种，一种是NAL UNIT stream(RTP),一种是 bits stream,两者可以互相转换。我们分析的这个是 bit stream,根据Annex B00 00 00 01 67 42 00 1E 99 A0 B1 31 是 一个NAL，在两个00 00 00 01之间0110 0111 0100 0010 0000 0000 0001 1110 1001 1001 1010 0000 1011 0001 0011 0001forbidden_zero_bit（1） ＝ 0nal_ref_idc（2）＝ 11nal_unit_type（5） ＝ 0 0111：seq_parameter_set_rbsp( )所以 processSPS

0110 0111 0100 0010 0000 0000 0001 1110 1001 1001 1010 0000 1011 0001 0011 0001profile_idc(8):42：0100 0010

0110 0111 0100 0010 0000 0000 0001 1110 1001 1001 1010 0000 1011 0001 0011 0001

constraint_set0_flag(1):0constraint_set1_flag(1):0constraint_set2_flag(1):0constraint_set3_flag(1):0reserved_zero_4bits(4):00110 0111 0100 0010 0000 0000 0001 1110 1001 1001 1010 0000 1011 0001 0011 0001

level_idc(8):1Eseq_parameter_set_id(UE(V)):ue(v): unsigned integer Exp-Golomb-coded syntax element with the left bit first. The parsing process for this descriptor is specified in subclause 9.1uvlC: 1001：根据Table9.1 ， value= 0,只占1bit.根据profile_idc忽略掉一部分。log2_max_frame_num_minus4(ue(v): 001 1001,len = 5,value= 5pic_order_cnt_type(ue(v)):01 1010,len = 3,value = 2根据pic_order_cnt_type忽略几个参数num_ref_frames（ue）：010,len = 3,value = 1

0110 0111 0100 0010 0000 0000 0001 1110 1001 1001 1010 0000 1011 0001 0011 0001gaps_in_frame_num_value_allowed_flag(1) = 0pic_width_in_mbs_minus1(ue):000 1011 ,len = 7,value = 10;pic_height_in_map_units_minus1(ue):0001 001,len = 7,value = 8frame_mbs_only_flag(1) = 1忽略1direct_8x8_inference_flag（1）:0忽略vui_parameters_present_flag(1):0忽略NALU结束

0110 1000(68)forbidden_zero_bit（1） ＝ 0nal_ref_idc（2）＝ 11nal_unit_type（5） ＝01000：pic_parameter_set_rbsp( ),7.3.2.21100 (C)pic_parameter_set_id (ue)=0seq_parameter_set_id(ue)=0entropy_coding_mode_flag(1) :0, 重要的flag,0 表示编码Exp-Golomb coded and CAVLC,1表示CABACpic_order_present_flag(1):01110 (E)num_slice_groups_minus1(ue):0忽略num_ref_idx_l0_active_minus1（ue）:0num_ref_idx_l1_active_minus1(ue):0weighted_pred_flag(1);00011 1000 1000 0000 (38 80)weighted_bipred_idc(2):00pic_init_qp_minus26 /* relative to 26 */(se):0pic_init_qs_minus26 /* relative to 26 */(se):0chroma_qp_index_offset(se):0deblocking_filter_control_present_flag(1);0constrained_intra_pred_flag(1):0redundant_pic_cnt_present_flag(1):0忽略NALU结束

65 88 80 21 71 27 1B 88…….3888*16 byte65：0110 0101forbidden_zero_bit（1） ＝ 0nal_ref_idc（2）＝ 11nal_unit_type（5） ＝0 0101：slice_layer_without_partitioning_rbsp( ),IDR浈SliceSlice_Header:first_mb_in_slice(ue):0slice_type(ue):000 1000 = 7pic_parameter_set_id(ue) = 080 21：000 0000 0010 0001frame_num(u(v): frame_num is used as an identifier for pictures and shall be represented by log2_max_frame_num_minus4 + 4 bits,9 bits = 0忽略if( nal_unit_type = = 5 ) //IDR frameidr_pic_id(u(e)):0忽略N多ref_pic_list_reordering( ) 见7。3。3。1忽略，Islice,SI slice,B slicenal_ref_idc   =11 所以dec_ref_pic_marking( )nal_unit_type = 5，所以no_output_of_prior_pics_flag（1）：0long_term_reference_flag（1）：0忽略。。71 27001 0111 0001 0010 0111slice_qp_delta（se（v）：001 01 ，4：-2忽略

slice_data( ):7.3.4对I-Slice:忽略N多进入if( moreDataFlag ) { if( MbaffFrameFlag && ( CurrMbAddr % 2 = = 0 | |                  ( CurrMbAddr % 2 = = 1 && prevMbSkipped ) ) )mb_field_decoding_flagmacroblock_layer( )}mb_field_decoding_flag忽略macroblock_layer( )mb_type（ue（v）：0mb_pred( mb_type )prev_intra4x4_pred_mode_flag[ luma4x4BlkIdx ] （1bit, 对babac是ae(v)）:11 27:0001 0010 0111prev_intra4x4_pred_mode_flag[ 1 ] : 0001,0,0010010 0111prev_intra4x4_pred_mode_flag[ 2 ] : 0010,0,010prev_intra4x4_pred_mode_flag[ 3] : 0111,0,111……16个1b 88 00 3e cf. intra_chroma_pred_mode（ue(v)） : 最后的一个1bit:0

接下来是macroblock_layer的coded_block_pattern和run level,既系数c0 06 ad a0 181100 0000 0000 0110 1010 0000 0001 1000coded_block_pattern（me(v):0,根据，= 47，0x2fmb_qp_delta(se(v):0 len =1residual( )见7.3.5.3residual_block( LumaLevel[ i8x8 * 4 + i4x4 ], 16 )coeff_token(ce(v): 00 0000 0000 0110 1nc = 0(left block and top block 相关的)：

len: {   // 0702

{ 1, 6, 8, 9,10,11,13,13,13,14,14,15,15,16,16,16,16},

{ 0, 2, 6, 8, 9,10,11,13,13,14,14,15,15,15,16,16,16},

{ 0, 0, 3, 7, 8, 9,10,11,13,13,14,14,15,15,16,16,16},

{ 0, 0, 0, 5, 6, 7, 8, 9,10,11,13,14,14,15,15,16,16},

},

{

{ 2, 6, 6, 7, 8, 8, 9,11,11,12,12,12,13,13,13,14,14},

{ 0, 2, 5, 6, 6, 7, 8, 9,11,11,12,12,13,13,14,14,14},

{ 0, 0, 3, 6, 6, 7, 8, 9,11,11,12,12,13,13,13,14,14},

{ 0, 0, 0, 4, 4, 5, 6, 6, 7, 9,11,11,12,13,13,13,14},

},

{

{ 4, 6, 6, 6, 7, 7, 7, 7, 8, 8, 9, 9, 9,10,10,10,10},

{ 0, 4, 5, 5, 5, 5, 6, 6, 7, 8, 8, 9, 9, 9,10,10,10},

{ 0, 0, 4, 5, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,10,10,10},

{ 0, 0, 0, 4, 4, 4, 4, 4, 5, 6, 7, 8, 8, 9,10,10,10},

},

code:

{ 1, 5, 7, 7, 7, 7,15,11, 8,15,11,15,11,15,11, 7,4},

{ 0, 1, 4, 6, 6, 6, 6,14,10,14,10,14,10, 1,14,10,6},

{ 0, 0, 1, 5, 5, 5, 5, 5,13, 9,13, 9,13, 9,13, 9,5},

{ 0, 0, 0, 3, 3, 4, 4, 4, 4, 4,12,12, 8,12, 8,12,8},

},

{

{ 3,11, 7, 7, 7, 4, 7,15,11,15,11, 8,15,11, 7, 9,7},

{ 0, 2, 7,10, 6, 6, 6, 6,14,10,14,10,14,10,11, 8,6},

{ 0, 0, 3, 9, 5, 5, 5, 5,13, 9,13, 9,13, 9, 6,10,5},

{ 0, 0, 0, 5, 4, 6, 8, 4, 4, 4,12, 8,12,12, 8, 1,4},

},

{

{15,15,11, 8,15,11, 9, 8,15,11,15,11, 8,13, 9, 5,1},

{ 0,14,15,12,10, 8,14,10,14,14,10,14,10, 7,12, 8,4},

{ 0, 0,13,14,11, 9,13, 9,13,10,13, 9,13, 9,11, 7,3},

{ 0, 0, 0,12,11,10, 9, 8,13,12,12,12, 8,12,10, 6,2},

},根据表查的：code = 13,len = 15，i= 12，j=2所以numcoeff = 12,numtrailingones = 2010 0000 0001 1000: totalzeros:根据numcoeff

int lentab[TOTRUN_NUM][16] =

{

{ 1,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9},

{ 3,3,3,3,3,4,4,4,4,5,5,6,6,6,6},

{ 4,3,3,3,4,4,3,3,4,5,5,6,5,6},

{ 5,3,4,4,3,3,3,4,3,4,5,5,5},

{ 4,4,4,3,3,3,3,3,4,5,4,5},

{ 6,5,3,3,3,3,3,3,4,3,6},

{ 6,5,3,3,3,2,3,4,3,6},

{ 6,4,5,3,2,2,3,3,6},

{ 6,6,4,2,2,3,2,5},

{ 5,5,3,2,2,2,4},

{ 4,4,3,3,1,3},

{ 4,4,2,1,3}, numcoeff开始

{ 3,3,1,2},

{ 2,2,1},

{ 1,1},

};

int codtab[TOTRUN_NUM][16] =

{

{1,3,2,3,2,3,2,3,2,3,2,3,2,3,2,1},

{7,6,5,4,3,5,4,3,2,3,2,3,2,1,0},

{5,7,6,5,4,3,4,3,2,3,2,1,1,0},

{3,7,5,4,6,5,4,3,3,2,2,1,0},

{5,4,3,7,6,5,4,3,2,1,1,0},

{1,1,7,6,5,4,3,2,1,1,0},

{1,1,5,4,3,3,2,1,1,0},

{1,1,1,3,3,2,2,1,0},

{1,0,1,3,2,1,1,1,},

{1,0,1,3,2,1,1,},

{0,1,1,2,1,3},

{0,1,1,1,1}, numcoeff开始

{0,1,1,1},

{0,1,1},

{0,1},

};