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一段H264数据的分析

發(fā)布時(shí)間：2023/12/10 编程问答 29 豆豆

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目錄(?)[-]

分析00 00 00 01 67 42 00 1E 99 A0 B1 31 00 00 00 01

分析00 00 00 01 68 CE 38 80 00 00 00 01

分析00 00 00 01 67 42 00 1E 99 A0 B1 31 00 00 00 01

H264的數(shù)據(jù)流分為兩種，一種是NAL UNIT stream(RTP),一種是 bits stream,
兩者可以互相轉(zhuǎn)換。我們分析的這個(gè)是 bit stream,根據(jù)Annex B
00 00 00 01 67 42 00 1E 99 A0 B1 31 是一個(gè)NAL，在兩個(gè)00 00 00 01之間
0110 0111?0100 0010 0000 0000 0001 1110 1001 1001 1010 0000 1011 0001 0011 0001
forbidden_zero_bit（1）?＝ 0
nal_ref_idc（2）＝ 11
nal_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 0001
profile_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):0
constraint_set1_flag(1):0
constraint_set2_flag(1):0
constraint_set3_flag(1):0
reserved_zero_4bits(4):0
0110 0111 0100 0010 0000 0000?0001 1110 1001 1001 1010?0000 1011 0001 0011 0001

level_idc(8):1E
seq_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 9.1
uvlC: 1001：根據(jù)Table9.1 ， value= 0,只占1bit.
根據(jù)profile_idc忽略掉一部分。
log2_max_frame_num_minus4(ue(v): 001 10,len = 5,value= 5
pic_order_cnt_type(ue(v)):01 1,len = 3,value = 2
根據(jù)pic_order_cnt_type忽略幾個(gè)參數(shù)
num_ref_frames（ue）：010,len = 3,value = 1

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

分析00 00 00 01 68 CE 38 80 00 00 00 01

0110 1000(68)
forbidden_zero_bit（1）?＝ 0
nal_ref_idc（2）＝ 11
nal_unit_type（5）?＝01000：pic_parameter_set_rbsp( ),7.3.2.2
1100?(C)
pic_parameter_set_id (ue)=0
seq_parameter_set_id(ue)=0
entropy_coding_mode_flag(1) :0,?重要的flag,0?表示編碼Exp-Golomb coded and CAVLC,1表示CABAC
pic_order_present_flag(1):0
1110?(E)
num_slice_groups_minus1(ue):0
忽略
num_ref_idx_l0_active_minus1（ue）:0
num_ref_idx_l1_active_minus1(ue):0
weighted_pred_flag(1);0
0011 1000 1000 0000?(38 80)
weighted_bipred_idc(2):00
pic_init_qp_minus26?/* relative to 26 */(se):0
pic_init_qs_minus26?/* relative to 26 */(se):0
chroma_qp_index_offset(se):0
deblocking_filter_control_present_flag(1);0
constrained_intra_pred_flag(1):0
redundant_pic_cnt_present_flag(1):0
忽略
NALU結(jié)束

65 88 80 21 71 27 1B 88…….3888*16 byte
65：0110 0101
forbidden_zero_bit（1）?＝ 0
nal_ref_idc（2）＝ 11
nal_unit_type（5）?＝0 0101：slice_layer_without_partitioning_rbsp( ),IDR湞
Slice
Slice_Header:
first_mb_in_slice(ue):0
slice_type(ue):000 1000 = 7
pic_parameter_set_id(ue) = 0
80 21：000 0000 0010 0001
frame_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 frame
idr_pic_id(u(e)):0
忽略N多
ref_pic_list_reordering( ) 見7。3。3。1忽略，Islice,SI slice,B slice
nal_ref_idc? ?=11 所以dec_ref_pic_marking( )
nal_unit_type = 5，所以
no_output_of_prior_pics_flag（1）：0
long_term_reference_flag（1）：0
忽略
。。71 27
001 0111 0001 0010 0111
slice_qp_delta（se（v）：001 01?，4：-2
忽略

slice_data( ):7.3.4
對(duì)I-Slice:忽略N多
進(jìn)入if( moreDataFlag ) { if( MbaffFrameFlag && ( CurrMbAddr % 2 = = 0 | |? ?? ?? ?? ?? ?? ?( CurrMbAddr % 2 = = 1 && prevMbSkipped ) ) )mb_field_decoding_flag
macroblock_layer( )}
mb_field_decoding_flag忽略
macroblock_layer( )
mb_type（ue（v）：0
mb_pred( mb_type )
prev_intra4x4_pred_mode_flag[?luma4x4BlkIdx?]?（1bit,?對(duì)babac是ae(v)）:1
1 27:0001 0010 0111
prev_intra4x4_pred_mode_flag[?1?] : 0001,0,001
0010 0111
prev_intra4x4_pred_mode_flag[?2?] : 0010,0,010
prev_intra4x4_pred_mode_flag[?3] : 0111,0,111
……16個(gè)
1b 88 00 3e cf.?
intra_chroma_pred_mode（ue(v)）?:?最后的一個(gè)1bit:0

接下來是macroblock_layer的coded_block_pattern和run level,既系數(shù)
c0 06 ad a0 18
1100 0000 0000 0110 1010 0000 0001 1000
coded_block_pattern（me(v):0,根據(jù)，= 47，0x2f
mb_qp_delta(se(v):0 len =1
residual( )見7.3.5.3
residual_block( LumaLevel[ i8x8 * 4 + i4x4 ], 16 )
coeff_token(ce(v): 00 0000 0000 0110 1
nc = 0(left block and top block?相關(guān)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},

},
根據(jù)表查的：
code = 13,len = 15，i= 12，j=2
所以numcoeff = 12,numtrailingones = 2
010 0000 0001 1000: totalzeros:根據(jù)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開始

{ 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開始

{0,1,1,1},

{0,1,1},

{0,1},

};

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