H264--4--H264编码

-----------------------------------

编码器输出格式

----------------------------------

总的来说H264的码流的打包方式有两种，一种为annex-b byte stream format的格式，这个是绝大部分编码器的默认输出格式，就是每个帧的开头的3~4个字节是H264的start_code,0x00000001或者0x000001。
另一种是原始的NAL打包格式，就是开始的若干字节（1，2，4字节）是NAL的长度，而不是start_code,此时必须借助某个全局的数据来获得编码器的profile,level,PPS,SPS等信息才可以解码。

@之前还疑惑过PPS 和SPS是哪里来的，答案是编码器给出的。

------------------------------

编码数据流分析

------------------------------

首先明确一下，NAL数据流的组成：开始码+NAL头（forbidden_bit+nal_ref+nal_type）+RBSP

下面对一段H264编码数据流进行分析。

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

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AnnexB

00 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 0001

forbidden_zero_bit（1）＝ 0//网络传输正确

nal_ref_idc（2）＝ 11//参考值为3

nal_unit_type（5）＝ 0 0111：seq_parameter_set_rbsp( )//7，序列参数集

说明这个NALU的RBSP里装的是SPS数据，所以 processSPS

profile_idc(8):42：0100 0010

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

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 subclause9.1

uvlC: 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= 5

pic_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

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结束

68 CE 38 80 00 00 00 01

0110 1000

forbidden_zero_bit（1）＝ 0

nal_ref_idc（2）＝ 11

nal_unit_type（5）＝01000：pic_parameter_set_rbsp( ),7.3.2.2//8图像参数集

1100

pic_parameter_set_id (ue)=0

seq_parameter_set_id(ue)=0

entropy_coding_mode_flag(1) :0, 重要的flag,0表示编码Exp-Golomb coded and CAVLC,1表示CABAC

pic_order_present_flag(1):0

1110

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

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结束

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帧

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( ) 见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

对I-Slice:忽略N多

进入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,对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 18

1100 0000 0000 0110 1010 0000 0001 1000

coded_block_pattern（me(v):0,根据T= 47，0x2f

mb_qp_delta(se(v):):0 len =1

residual( )见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 = 2

010 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},

};

Code = 1,len = 2,i=2,j = 0, totzeros = 2

Read run: 0 0000 0001 1000根据totzeros = 2

int lentab[TOTRUN_NUM][16] =

{

{1,1},

{1,2,2},

{2,2,2,2},

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

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

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

{3,3,3,3,3,3,3,4,5,6,7,8,9,10,11},

};

int codtab[TOTRUN_NUM][16] =

{

{1,0},

{1,1,0},

{3,2,1,0},

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

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

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

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

Code = 1,len =1,I = 0,j = 0

0.1.1 Slice data syntax

slice_data( ) {	C	Descriptor
if( entropy_coding_mode_flag )
while( !byte_aligned( ) )
cabac_alignment_one_bit	2	f(1)
CurrMbAddr = first_mb_in_slice * ( 1 + MbaffFrameFlag )
moreDataFlag = 1
prevMbSkipped = 0
do {
if( slice_type != I && slice_type != SI )
if( !entropy_coding_mode_flag ) {
mb_skip_run	2	ue(v)
prevMbSkipped = ( mb_skip_run > 0 )
for( i=0; i<mb_skip_run; i++ )
CurrMbAddr = NextMbAddress( CurrMbAddr )
moreDataFlag = more_rbsp_data( )
} else {
mb_skip_flag	2	ae(v)
moreDataFlag = !mb_skip_flag
}
if( moreDataFlag ) {
if( MbaffFrameFlag && ( CurrMbAddr % 2 = = 0 \| \| ( CurrMbAddr % 2 = = 1 && prevMbSkipped ) ) )
mb_field_decoding_flag	2	u(1) \| ae(v)
macroblock_layer( )	2 \| 3 \| 4
}
if( !entropy_coding_mode_flag )
moreDataFlag = more_rbsp_data( )
else {
if( slice_type != I && slice_type != SI )
prevMbSkipped = mb_skip_flag
if( MbaffFrameFlag && CurrMbAddr % 2 = = 0 )
moreDataFlag = 1
else {
end_of_slice_flag	2	ae(v)
moreDataFlag = !end_of_slice_flag
}
}
CurrMbAddr = NextMbAddress( CurrMbAddr )
} while( moreDataFlag )
}

se(v) : CABAC正式介绍。根据Table 9 5 – coeff_token mapping to TotalCoeff( coeff_token ) and TrailingOnes( coeff_token )。

chroma_format_idc 无

Table 9‑1 – Bit strings with “prefix” and “suffix” bits and assignment to codeNum ranges (informative)

Bit string form	Range of codeNum
1	0
0 1 x₀	1-2
0 0 1 x₁ x₀	3-6
0 0 0 1 x₂ x₁ x₀	7-14
0 0 0 0 1 x₃ x₂ x₁ x₀	15-30
0 0 0 0 0 1 x₄ x₃ x₂ x₁ x₀	31-62
…	…

0.1.1.1 Slice layer without partitioning RBSP syntax

slice_layer_without_partitioning_rbsp( ) {	C	Descriptor
slice_header( )	2
slice_data( ) /* all categories of slice_data( ) syntax */	2 \| 3 \| 4
rbsp_slice_trailing_bits( )	2
}

0.1.1.2 Sequence parameter set RBSP syntax

seq_parameter_set_rbsp( ) {	C	Descriptor
profile_idc	0	u(8)
constraint_set0_flag	0	u(1)
constraint_set1_flag	0	u(1)
constraint_set2_flag	0	u(1)
constraint_set3_flag	0	u(1)
reserved_zero_4bits /* equal to 0 */	0	u(4)
level_idc	0	u(8)
seq_parameter_set_id	0	ue(v)
if( profile_idc = = 100 \| \| profile_idc = = 110 \| \| profile_idc = = 122 \| \| profile_idc = = 144 ) {
chroma_format_idc	0	ue(v)
if( chroma_format_idc = = 3 )
residual_colour_transform_flag	0	u(1)
bit_depth_luma_minus8	0	ue(v)
bit_depth_chroma_minus8	0	ue(v)
qpprime_y_zero_transform_bypass_flag	0	u(1)
seq_scaling_matrix_present_flag	0	u(1)
if( seq_scaling_matrix_present_flag )
for( i = 0; i < 8; i++ ) {
seq_scaling_list_present_flag[ i]	0	u(1)
if( seq_scaling_list_present_flag[ i ] )
if( i < 6 )
scaling_list( ScalingList4x4[ i ], 16, UseDefaultScalingMatrix4x4Flag[ i ])	0
else
scaling_list( ScalingList8x8[ i – 6 ], 64, UseDefaultScalingMatrix8x8Flag[ i – 6 ] )	0
}
}
log2_max_frame_num_minus4	0	ue(v)
pic_order_cnt_type	0	ue(v)
if( pic_order_cnt_type = = 0 )
log2_max_pic_order_cnt_lsb_minus4	0	ue(v)
else if( pic_order_cnt_type = = 1 ) {
delta_pic_order_always_zero_flag	0	u(1)
offset_for_non_ref_pic	0	se(v)
offset_for_top_to_bottom_field	0	se(v)
num_ref_frames_in_pic_order_cnt_cycle	0	ue(v)
for( i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; i++ )
offset_for_ref_frame[ i ]	0	se(v)
}
num_ref_frames	0	ue(v)
gaps_in_frame_num_value_allowed_flag	0	u(1)
pic_width_in_mbs_minus1	0	ue(v)
pic_height_in_map_units_minus1	0	ue(v)
frame_mbs_only_flag	0	u(1)
if( !frame_mbs_only_flag )
mb_adaptive_frame_field_flag	0	u(1)
direct_8x8_inference_flag	0	u(1)
frame_cropping_flag	0	u(1)
if( frame_cropping_flag ) {
frame_crop_left_offset	0	ue(v)
frame_crop_right_offset	0	ue(v)
frame_crop_top_offset	0	ue(v)
frame_crop_bottom_offset	0	ue(v)
}
vui_parameters_present_flag	0	u(1)
if( vui_parameters_present_flag )
vui_parameters( )	0
rbsp_trailing_bits( )	0
}

Table 7‑1 – NAL unit type codes

nal_unit_type	Content of NAL unit and RBSP syntax structure	C
0	Unspecified
1	Coded slice of a non-IDR picture slice_layer_without_partitioning_rbsp( )	2, 3, 4
2	Coded slice data partition A slice_data_partition_a_layer_rbsp( )	2
3	Coded slice data partition B slice_data_partition_b_layer_rbsp( )	3
4	Coded slice data partition C slice_data_partition_c_layer_rbsp( )	4
5	Coded slice of an IDR picture slice_layer_without_partitioning_rbsp( )	2, 3
6	Supplemental enhancement information (SEI) sei_rbsp( )	5
7	Sequence parameter set seq_parameter_set_rbsp( )	0
8	Picture parameter set pic_parameter_set_rbsp( )	1
9	Access unit delimiter access_unit_delimiter_rbsp( )	6
10	End of sequence end_of_seq_rbsp( )	7
11	End of stream end_of_stream_rbsp( )	8
12	Filler data filler_data_rbsp( )	9
13	Sequence parameter set extension seq_parameter_set_extension_rbsp( )	10
14..18	Reserved
19	Coded slice of an auxiliary coded picture without partitioning slice_layer_without_partitioning_rbsp( )	2, 3, 4
20..23	Reserved
24..31	Unspecified

byte_stream_nal_unit( NumBytesInNALunit ) {	C	Descriptor
while( next_bits( 24 ) != 0x000001 && next_bits( 32 ) != 0x00000001 )
leading_zero_8bits /* equal to 0x00 */		f(8)
if( next_bits( 24 ) != 0x000001 )
zero_byte /* equal to 0x00 */		f(8)
start_code_prefix_one_3bytes /* equal to 0x000001 */		f(24)
nal_unit( NumBytesInNALunit)
while( more_data_in_byte_stream( ) && next_bits( 24 ) != 0x000001 && next_bits( 32 ) != 0x00000001 )
trailing_zero_8bits /* equal to 0x00 */		f(8)
}

0.1.1.3 Picture parameter set RBSP syntax

pic_parameter_set_rbsp( ) {	C	Descriptor
pic_parameter_set_id	1	ue(v)
seq_parameter_set_id	1	ue(v)
entropy_coding_mode_flag	1	u(1)
pic_order_present_flag	1	u(1)
num_slice_groups_minus1	1	ue(v)
if( num_slice_groups_minus1 > 0 ) {
slice_group_map_type	1	ue(v)
if( slice_group_map_type = = 0 )
for( iGroup = 0; iGroup <= num_slice_groups_minus1; iGroup++ )
run_length_minus1[ iGroup ]	1	ue(v)
else if( slice_group_map_type = = 2 )
for( iGroup = 0; iGroup < num_slice_groups_minus1; iGroup++ ) {
top_left[ iGroup ]	1	ue(v)
bottom_right[ iGroup ]	1	ue(v)
}
else if( slice_group_map_type = = 3 \| \| slice_group_map_type = = 4 \| \| slice_group_map_type = = 5 ) {
slice_group_change_direction_flag	1	u(1)
slice_group_change_rate_minus1	1	ue(v)
} else if( slice_group_map_type = = 6 ) {
pic_size_in_map_units_minus1	1	ue(v)
for( i = 0; i <= pic_size_in_map_units_minus1; i++ )
slice_group_id[ i ]	1	u(v)
}
}
num_ref_idx_l0_active_minus1	1	ue(v)
num_ref_idx_l1_active_minus1	1	ue(v)
weighted_pred_flag	1	u(1)
weighted_bipred_idc	1	u(2)
pic_init_qp_minus26 /* relative to 26 */	1	se(v)
pic_init_qs_minus26 /* relative to 26 */	1	se(v)
chroma_qp_index_offset	1	se(v)
deblocking_filter_control_present_flag	1	u(1)
constrained_intra_pred_flag	1	u(1)
redundant_pic_cnt_present_flag	1	u(1)
if( more_rbsp_data( ) ) {
transform_8x8_mode_flag	1	u(1)
pic_scaling_matrix_present_flag	1	u(1)
if( pic_scaling_matrix_present_flag )
for( i = 0; i < 6 + 2* transform_8x8_mode_flag; i++ ) {
pic_scaling_list_present_flag[ i]	1	u(1)
if( pic_scaling_list_present_flag[ i ] )
if( i < 6 )
scaling_list( ScalingList4x4[ i ], 16, UseDefaultScalingMatrix4x4Flag[ i ] )	1
else
scaling_list( ScalingList8x8[ i – 6 ], 64, UseDefaultScalingMatrix8x8Flag[ i – 6 ] )	1
}
second_chroma_qp_index_offset	1	se(v)
}
rbsp_trailing_bits( )	1
}

0.1.2 Slice header syntax

slice_header( ) {	C	Descriptor
first_mb_in_slice	2	ue(v)
slice_type	2	ue(v)
pic_parameter_set_id	2	ue(v)
frame_num	2	u(v)
if( !frame_mbs_only_flag ) {
field_pic_flag	2	u(1)
if( field_pic_flag )
bottom_field_flag	2	u(1)
}
if( nal_unit_type = = 5 )
idr_pic_id	2	ue(v)
if( pic_order_cnt_type = = 0 ) {
pic_order_cnt_lsb	2	u(v)
if( pic_order_present_flag && !field_pic_flag )
delta_pic_order_cnt_bottom	2	se(v)
}
if( pic_order_cnt_type = = 1 && !delta_pic_order_always_zero_flag ) {
delta_pic_order_cnt[ 0 ]	2	se(v)
if( pic_order_present_flag && !field_pic_flag )
delta_pic_order_cnt[ 1 ]	2	se(v)
}
if( redundant_pic_cnt_present_flag )
redundant_pic_cnt	2	ue(v)
if( slice_type = = B )
direct_spatial_mv_pred_flag	2	u(1)
if( slice_type = = P \| \| slice_type = = SP \| \| slice_type = = B ) {
num_ref_idx_active_override_flag	2	u(1)
if( num_ref_idx_active_override_flag ) {
num_ref_idx_l0_active_minus1	2	ue(v)
if( slice_type = = B )
num_ref_idx_l1_active_minus1	2	ue(v)
}
}
ref_pic_list_reordering( )	2
if( ( weighted_pred_flag && ( slice_type = = P \| \| slice_type = = SP ) ) \| \| ( weighted_bipred_idc = = 1 && slice_type = = B ) )
pred_weight_table( )	2
if( nal_ref_idc != 0 )
dec_ref_pic_marking( )	2
if( entropy_coding_mode_flag && slice_type != I && slice_type != SI )
cabac_init_idc	2	ue(v)
slice_qp_delta	2	se(v)
if( slice_type = = SP \| \| slice_type = = SI ) {
if( slice_type = = SP )
sp_for_switch_flag	2	u(1)
slice_qs_delta	2	se(v)
}
if( deblocking_filter_control_present_flag ) {
disable_deblocking_filter_idc	2	ue(v)
if( disable_deblocking_filter_idc != 1 ) {
slice_alpha_c0_offset_div2	2	se(v)
slice_beta_offset_div2	2	se(v)
}
}
if( num_slice_groups_minus1 > 0 && slice_group_map_type >= 3 && slice_group_map_type <= 5)
slice_group_change_cycle	2	u(v)
}

0.1.3 Slice data syntax

slice_data( ) {	C	Descriptor
if( entropy_coding_mode_flag )
while( !byte_aligned( ) )
cabac_alignment_one_bit	2	f(1)
CurrMbAddr = first_mb_in_slice * ( 1 + MbaffFrameFlag )
moreDataFlag = 1
prevMbSkipped = 0
do {
if( slice_type != I && slice_type != SI )
if( !entropy_coding_mode_flag ) {
mb_skip_run	2	ue(v)
prevMbSkipped = ( mb_skip_run > 0 )
for( i=0; i<mb_skip_run; i++ )
CurrMbAddr = NextMbAddress( CurrMbAddr )
moreDataFlag = more_rbsp_data( )
} else {
mb_skip_flag	2	ae(v)
moreDataFlag = !mb_skip_flag
}
if( moreDataFlag ) {
if( MbaffFrameFlag && ( CurrMbAddr % 2 = = 0 \| \| ( CurrMbAddr % 2 = = 1 && prevMbSkipped ) ) )
mb_field_decoding_flag	2	u(1) \| ae(v)
macroblock_layer( )	2 \| 3 \| 4
}
if( !entropy_coding_mode_flag )
moreDataFlag = more_rbsp_data( )
else {
if( slice_type != I && slice_type != SI )
prevMbSkipped = mb_skip_flag
if( MbaffFrameFlag && CurrMbAddr % 2 = = 0 )
moreDataFlag = 1
else {
end_of_slice_flag	2	ae(v)
moreDataFlag = !end_of_slice_flag
}
}
CurrMbAddr = NextMbAddress( CurrMbAddr )
} while( moreDataFlag )
}

The variable MbaffFrameFlag is derived as follows.

MbaffFrameFlag = ( mb_adaptive_frame_field_flag && !field_pic_flag ) (7-22)

0.1.4 Macroblock layer syntax

macroblock_layer( ) {	C	Descriptor
mb_type	2	ue(v) \| ae(v)
if( mb_type = = I_PCM ) {
while( !byte_aligned( ) )
pcm_alignment_zero_bit	2	f(1)
for( i = 0; i < 256; i++ )
pcm_sample_luma[ i ]	2	u(v)
for( i = 0; i < 2 * MbWidthC * MbHeightC; i++ )
pcm_sample_chroma[ i ]	2	u(v)
} else {
noSubMbPartSizeLessThan8x8Flag = 1
if( mb_type != I_NxN && MbPartPredMode( mb_type, 0 ) != Intra_16x16 && NumMbPart( mb_type ) = = 4 ) {
sub_mb_pred( mb_type )	2
for( mbPartIdx = 0; mbPartIdx < 4; mbPartIdx++ )
if( sub_mb_type[ mbPartIdx ] != B_Direct_8x8 ) {
if( NumSubMbPart( sub_mb_type[ mbPartIdx ] ) > 1 )
noSubMbPartSizeLessThan8x8Flag = 0
} else if( !direct_8x8_inference_flag )
noSubMbPartSizeLessThan8x8Flag = 0
} else {
if( transform_8x8_mode_flag && mb_type = = I_NxN )
transform_size_8x8_flag	2	u(1) \| ae(v)
mb_pred( mb_type )	2
}
if( MbPartPredMode( mb_type, 0 ) != Intra_16x16 ) {
coded_block_pattern	2	me(v) \| ae(v)
if( CodedBlockPatternLuma > 0 && transform_8x8_mode_flag && mb_type != I_NxN && noSubMbPartSizeLessThan8x8Flag && ( mb_type != B_Direct_16x16 \| \| direct_8x8_inference_flag ) )
transform_size_8x8_flag	2	u(1) \| ae(v)
}
if( CodedBlockPatternLuma > 0 \| \| CodedBlockPatternChroma > 0 \| \| MbPartPredMode( mb_type, 0 ) = = Intra_16x16 ) {
mb_qp_delta	2	se(v) \| ae(v)
residual( )	3 \| 4
}
}
}

0.1.4.1 Macroblock prediction syntax

mb_pred( mb_type ) {	C	Descriptor
if( MbPartPredMode( mb_type, 0 ) = = Intra_4x4 \| \| MbPartPredMode( mb_type, 0 ) = = Intra_8x8 \| \| MbPartPredMode( mb_type, 0 ) = = Intra_16x16 ) {
if( MbPartPredMode( mb_type, 0 ) = = Intra_4x4 )
for( luma4x4BlkIdx=0; luma4x4BlkIdx<16; luma4x4BlkIdx++ ) {
prev_intra4x4_pred_mode_flag[ luma4x4BlkIdx ]	2	u(1) \| ae(v)
if( !prev_intra4x4_pred_mode_flag[ luma4x4BlkIdx ] )
rem_intra4x4_pred_mode[ luma4x4BlkIdx ]	2	u(3) \| ae(v)
}
if( MbPartPredMode( mb_type, 0 ) = = Intra_8x8 )
for( luma8x8BlkIdx=0; luma8x8BlkIdx<4; luma8x8BlkIdx++ ) {
prev_intra8x8_pred_mode_flag[ luma8x8BlkIdx ]	2	u(1) \| ae(v)
if( !prev_intra8x8_pred_mode_flag[ luma8x8BlkIdx ] )
rem_intra8x8_pred_mode[ luma8x8BlkIdx ]	2	u(3) \| ae(v)
}
if( chroma_format_idc != 0 )
intra_chroma_pred_mode	2	ue(v) \| ae(v)
} else if( MbPartPredMode( mb_type, 0 ) != Direct ) {
for( mbPartIdx = 0; mbPartIdx < NumMbPart( mb_type ); mbPartIdx++)
if( ( num_ref_idx_l0_active_minus1 > 0 \| \| mb_field_decoding_flag ) && MbPartPredMode( mb_type, mbPartIdx ) != Pred_L1 )
ref_idx_l0[ mbPartIdx ]	2	te(v) \| ae(v)
for( mbPartIdx = 0; mbPartIdx < NumMbPart( mb_type ); mbPartIdx++)
if( ( num_ref_idx_l1_active_minus1 > 0 \| \| mb_field_decoding_flag ) && MbPartPredMode( mb_type, mbPartIdx ) != Pred_L0 )
ref_idx_l1[ mbPartIdx ]	2	te(v) \| ae(v)
for( mbPartIdx = 0; mbPartIdx < NumMbPart( mb_type ); mbPartIdx++)
if( MbPartPredMode ( mb_type, mbPartIdx ) != Pred_L1 )
for( compIdx = 0; compIdx < 2; compIdx++ )
mvd_l0[ mbPartIdx ][ 0 ][ compIdx ]	2	se(v) \| ae(v)
for( mbPartIdx = 0; mbPartIdx < NumMbPart( mb_type ); mbPartIdx++)
if( MbPartPredMode( mb_type, mbPartIdx ) != Pred_L0 )
for( compIdx = 0; compIdx < 2; compIdx++ )
mvd_l1[ mbPartIdx ][ 0 ][ compIdx ]	2	se(v) \| ae(v)
}
}

0.1.4.2 Residual data syntax

residual( ) {	C	Descriptor
if( !entropy_coding_mode_flag )
residual_block = residual_block_cavlc
else
residual_block = residual_block_cabac
if( MbPartPredMode( mb_type, 0 ) = = Intra_16x16 )
residual_block( Intra16x16DCLevel, 16 )	3
for( i8x8 = 0; i8x8 < 4; i8x8++ ) /* each luma 8x8 block */
if( !transform_size_8x8_flag \| \| !entropy_coding_mode_flag )
for( i4x4 = 0; i4x4 < 4; i4x4++ ) { /* each 4x4 sub-block of block */
if( CodedBlockPatternLuma & ( 1 << i8x8 ) )
if( MbPartPredMode( mb_type, 0 ) = = Intra_16x16 )
residual_block( Intra16x16ACLevel[ i8x8 * 4 + i4x4 ], 15 )	3
else
residual_block( LumaLevel[ i8x8 * 4 + i4x4 ], 16 )	3 \| 4
else if( MbPartPredMode( mb_type, 0 ) = = Intra_16x16 )
for( i = 0; i < 15; i++ )
Intra16x16ACLevel[ i8x8 * 4 + i4x4 ][ i ] = 0
else
for( i = 0; i < 16; i++ )
LumaLevel[ i8x8 * 4 + i4x4 ][ i ] = 0
if( !entropy_coding_mode_flag && transform_size_8x8_flag )
for( i = 0; i < 16; i++ )
LumaLevel8x8[ i8x8 ][ 4 * i + i4x4 ] = LumaLevel[ i8x8 * 4 + i4x4 ][ i ]
}
else if( CodedBlockPatternLuma & ( 1 << i8x8 ) )
residual_block( LumaLevel8x8[ i8x8 ], 64 )	3 \| 4
else
for( i = 0; i < 64; i++ )
LumaLevel8x8[ i8x8 ][ i ] = 0
if( chroma_format_idc != 0 ) {
NumC8x8 = 4 / ( SubWidthC * SubHeightC )
for( iCbCr = 0; iCbCr < 2; iCbCr++ )
if( CodedBlockPatternChroma & 3 ) /* chroma DC residual present */
residual_block( ChromaDCLevel[ iCbCr ], 4 * NumC8x8 )	3 \| 4
else
for( i = 0; i < 4 * NumC8x8; i++ )
ChromaDCLevel[ iCbCr ][ i ] = 0
for( iCbCr = 0; iCbCr < 2; iCbCr++ )
for( i8x8 = 0; i8x8 < NumC8x8; i8x8++ )
for( i4x4 = 0; i4x4 < 4; i4x4++ )
if( CodedBlockPatternChroma & 2 ) /* chroma AC residual present */
residual_block( ChromaACLevel[ iCbCr ][ i8x8*4+i4x4 ], 15)	3 \| 4
else
for( i = 0; i < 15; i++ )
ChromaACLevel[ iCbCr ][ i8x8*4+i4x4 ][ i ] = 0
}

residual_block_cavlc( coeffLevel, maxNumCoeff ) {	C	Descriptor
for( i = 0; i < maxNumCoeff; i++ )
coeffLevel[ i ] = 0
coeff_token	3 \| 4	ce(v)
if( TotalCoeff( coeff_token ) > 0 ) {
if( TotalCoeff( coeff_token ) > 10 && TrailingOnes( coeff_token ) < 3 )
suffixLength = 1
else
suffixLength = 0
for( i = 0; i < TotalCoeff( coeff_token ); i++ )
if( i < TrailingOnes( coeff_token ) ) {
trailing_ones_sign_flag	3 \| 4	u(1)
level[ i ] = 1 – 2 * trailing_ones_sign_flag
} else {
level_prefix	3 \| 4	ce(v)
levelCode = ( Min( 15, level_prefix ) << suffixLength )
if( suffixLength > 0 \| \| level_prefix >= 14 ) {
level_suffix	3 \| 4	u(v)
levelCode += level_suffix
}
if( level_prefix > = 15 && suffixLength = = 0 )
levelCode += 15
if( level_prefix > = 16 )
levelCode += ( 1 << ( level_prefix – 3 ) ) – 4096
if( i = = TrailingOnes( coeff_token ) && TrailingOnes( coeff_token ) < 3 )
levelCode += 2
if( levelCode % 2 = = 0 )
level[ i ] = ( levelCode + 2 ) >> 1
else
level[ i ] = ( –levelCode – 1 ) >> 1
if( suffixLength = = 0 )
suffixLength = 1
if( Abs( level[ i ] ) > ( 3 << ( suffixLength – 1 ) ) && suffixLength < 6 )
suffixLength++
}
if( TotalCoeff( coeff_token ) < maxNumCoeff ) {
total_zeros	3 \| 4	ce(v)
zerosLeft = total_zeros
} else
zerosLeft = 0
for( i = 0; i < TotalCoeff( coeff_token ) – 1; i++ ) {
if( zerosLeft > 0 ) {
run_before	3 \| 4	ce(v)
run[ i ] = run_before
} else
run[ i ] = 0
zerosLeft = zerosLeft – run[ i ]
}
run[ TotalCoeff( coeff_token ) – 1 ] = zerosLeft
coeffNum = ‑1
for( i = TotalCoeff( coeff_token ) – 1; i >= 0; i-- ) {
coeffNum += run[ i ] + 1
coeffLevel[ coeffNum ] = level[ i ]
}
}
}