嵌入式 H264参数语法文档： SPS、PPS、IDR以及NALU编码规律

// 【h264编码出的NALU规律】
// 第一帧 SPS【0 0 0 1 0x67】 PPS【0 0 0 1 0x68】 SEI【0 0 0 1 0x6】 IDR【0 0 0 1 0x65】
// p帧      P【0 0 0 1 0x61】
// I帧    SPS【0 0 0 1 0x67】 PPS【0 0 0 1 0x68】 IDR【0 0 0 1 0x65】
// 【mp4v2封装函数MP4WriteSample】
// 此函数接收I/P nalu,该nalu需要用4字节的数据大小头替换原有的起始头，并且数据大小为big-endian格式

示例文件下载地址：“NALU中SPS、PPS、SEI、IDR、P帧标识”

H.264码流第一个 NALU 是 SPS（序列参数集Sequence Parameter Set）
对应H264标准文档 7.3.2.1 序列参数集的语法进行解析

SPS参数解析// fill sps with content of p

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1. int InterpretSPS (VideoParameters *p_Vid, DataPartition *p, seq_parameter_set_rbsp_t *sps)  
2. {  
3.   unsigned i;  
4.   unsigned n_ScalingList;  
5.   int reserved_zero;  
6.   Bitstream *s = p->bitstream;  
7.   
8.   assert (p != NULL);  
9.   assert (p->bitstream != NULL);  
10.   assert (p->bitstream->streamBuffer != 0);  
11.   assert (sps != NULL);  
12.   
13.   p_Dec->UsedBits = 0;  
14.   
15.   sps->profile_idc                            = u_v  (8, "SPS: profile_idc"                           , s);  
16.   
17.   if ((sps->profile_idc!=BASELINE       ) &&  
18.       (sps->profile_idc!=MAIN           ) &&  
19.       (sps->profile_idc!=EXTENDED       ) &&  
20.       (sps->profile_idc!=FREXT_HP       ) &&  
21.       (sps->profile_idc!=FREXT_Hi10P    ) &&  
22.       (sps->profile_idc!=FREXT_Hi422    ) &&  
23.       (sps->profile_idc!=FREXT_Hi444    ) &&  
24.       (sps->profile_idc!=FREXT_CAVLC444 )  
25. #if (MVC_EXTENSION_ENABLE)  
26.       && (sps->profile_idc!=MVC_HIGH)  
27.       && (sps->profile_idc!=STEREO_HIGH)  
28. #endif  
29.       )  
30.   {  
31.     printf("Invalid Profile IDC (%d) encountered. /n", sps->profile_idc);  
32.     return p_Dec->UsedBits;  
33.   }  
34.   
35.   sps->constrained_set0_flag                  = u_1  (   "SPS: constrained_set0_flag"                 , s);  
36.   sps->constrained_set1_flag                  = u_1  (   "SPS: constrained_set1_flag"                 , s);  
37.   sps->constrained_set2_flag                  = u_1  (   "SPS: constrained_set2_flag"                 , s);  
38.   sps->constrained_set3_flag                  = u_1  (   "SPS: constrained_set3_flag"                 , s);  
39. #if (MVC_EXTENSION_ENABLE)  
40.   sps->constrained_set4_flag                  = u_1  (   "SPS: constrained_set4_flag"                 , s);  
41.   reserved_zero                               = u_v  (3, "SPS: reserved_zero_3bits"                   , s);  
42. #else  
43.   reserved_zero                               = u_v  (4, "SPS: reserved_zero_4bits"                   , s);  
44. #endif  
45.   assert (reserved_zero==0);  
46.   
47.   sps->level_idc                              = u_v  (8, "SPS: level_idc"                             , s);  
48.   
49.   sps->seq_parameter_set_id                   = ue_v ("SPS: seq_parameter_set_id"                     , s);  
50.   
51.   // Fidelity Range Extensions stuff  
52.   sps->chroma_format_idc = 1;  
53.   sps->bit_depth_luma_minus8   = 0;  
54.   sps->bit_depth_chroma_minus8 = 0;  
55.   p_Vid->lossless_qpprime_flag   = 0;  
56.   sps->separate_colour_plane_flag = 0;  
57.   
58.   if((sps->profile_idc==FREXT_HP   ) ||  
59.      (sps->profile_idc==FREXT_Hi10P) ||  
60.      (sps->profile_idc==FREXT_Hi422) ||  
61.      (sps->profile_idc==FREXT_Hi444) ||  
62.      (sps->profile_idc==FREXT_CAVLC444)  
63. #if (MVC_EXTENSION_ENABLE)  
64.      || (sps->profile_idc==MVC_HIGH)  
65.      || (sps->profile_idc==STEREO_HIGH)  
66. #endif  
67.      )  
68.   {  
69.     sps->chroma_format_idc                      = ue_v ("SPS: chroma_format_idc"                       , s);  
70.   
71.     if(sps->chroma_format_idc == YUV444)  
72.     {  
73.       sps->separate_colour_plane_flag           = u_1  ("SPS: separate_colour_plane_flag"              , s);  
74.     }  
75.   
76.     sps->bit_depth_luma_minus8                  = ue_v ("SPS: bit_depth_luma_minus8"                   , s);  
77.     sps->bit_depth_chroma_minus8                = ue_v ("SPS: bit_depth_chroma_minus8"                 , s);  
78.     //checking;  
79.     if((sps->bit_depth_luma_minus8+8 > sizeof(imgpel)*8) || (sps->bit_depth_chroma_minus8+8> sizeof(imgpel)*8))  
80.       error ("Source picture has higher bit depth than imgpel data type. /nPlease recompile with larger data type for imgpel.", 500);  
81.   
82.     p_Vid->lossless_qpprime_flag                  = u_1  ("SPS: lossless_qpprime_y_zero_flag"            , s);  
83.   
84.     sps->seq_scaling_matrix_present_flag        = u_1  (   "SPS: seq_scaling_matrix_present_flag"       , s);  
85.       
86.     if(sps->seq_scaling_matrix_present_flag)  
87.     {  
88.       n_ScalingList = (sps->chroma_format_idc != YUV444) ? 8 : 12;  
89.       for(i=0; iseq_scaling_list_present_flag[i]   = u_1  (   "SPS: seq_scaling_list_present_flag"         , s);  
90.         if(sps->seq_scaling_list_present_flag[i])  
91.         {  
92.           if(i<6) scaling_list="">ScalingList4x4[i], 16, &sps->UseDefaultScalingMatrix4x4Flag[i], s);  
93.           else  
94.             Scaling_List(sps->ScalingList8x8[i-6], 64, &sps->UseDefaultScalingMatrix8x8Flag[i-6], s);  
95.         }  
96.       }  
97.     }  
98.   }  
99.   
100.   sps->log2_max_frame_num_minus4              = ue_v ("SPS: log2_max_frame_num_minus4"                , s);  
101.   sps->pic_order_cnt_type                     = ue_v ("SPS: pic_order_cnt_type"                       , s);  
102.   
103.   if (sps->pic_order_cnt_type == 0)  
104.     sps->log2_max_pic_order_cnt_lsb_minus4 = ue_v ("SPS: log2_max_pic_order_cnt_lsb_minus4"           , s);  
105.   else if (sps->pic_order_cnt_type == 1)  
106.   {  
107.     sps->delta_pic_order_always_zero_flag      = u_1  ("SPS: delta_pic_order_always_zero_flag"       , s);  
108.     sps->offset_for_non_ref_pic                = se_v ("SPS: offset_for_non_ref_pic"                 , s);  
109.     sps->offset_for_top_to_bottom_field        = se_v ("SPS: offset_for_top_to_bottom_field"         , s);  
110.     sps->num_ref_frames_in_pic_order_cnt_cycle = ue_v ("SPS: num_ref_frames_in_pic_order_cnt_cycle"  , s);  
111.     for(i=0; inum_ref_frames_in_pic_order_cnt_cycle; i++)  
112.       sps->offset_for_ref_frame[i]               = se_v ("SPS: offset_for_ref_frame[i]"              , s);  
113.   }  
114.   sps->num_ref_frames                        = ue_v ("SPS: num_ref_frames"                         , s);  
115.   sps->gaps_in_frame_num_value_allowed_flag  = u_1  ("SPS: gaps_in_frame_num_value_allowed_flag"   , s);  
116.   sps->pic_width_in_mbs_minus1               = ue_v ("SPS: pic_width_in_mbs_minus1"                , s);  
117.   sps->pic_height_in_map_units_minus1        = ue_v ("SPS: pic_height_in_map_units_minus1"         , s);  
118.   sps->frame_mbs_only_flag                   = u_1  ("SPS: frame_mbs_only_flag"                    , s);  
119.   if (!sps->frame_mbs_only_flag)  
120.   {  
121.     sps->mb_adaptive_frame_field_flag        = u_1  ("SPS: mb_adaptive_frame_field_flag"           , s);  
122.   }  
123.   sps->direct_8x8_inference_flag             = u_1  ("SPS: direct_8x8_inference_flag"              , s);  
124.   sps->frame_cropping_flag                   = u_1  ("SPS: frame_cropping_flag"                    , s);  
125.   
126.   if (sps->frame_cropping_flag)  
127.   {  
128.     sps->frame_cropping_rect_left_offset      = ue_v ("SPS: frame_cropping_rect_left_offset"           , s);  
129.     sps->frame_cropping_rect_right_offset     = ue_v ("SPS: frame_cropping_rect_right_offset"          , s);  
130.     sps->frame_cropping_rect_top_offset       = ue_v ("SPS: frame_cropping_rect_top_offset"            , s);  
131.     sps->frame_cropping_rect_bottom_offset    = ue_v ("SPS: frame_cropping_rect_bottom_offset"         , s);  
132.   }  
133.   sps->vui_parameters_present_flag           = (Boolean) u_1  ("SPS: vui_parameters_present_flag"      , s);  
134.   
135.   InitVUI(sps);  
136.   ReadVUI(p, sps);  
137.   
138.   sps->Valid = TRUE;  
139.   return p_Dec->UsedBits;  
140. }  

H.264码流第二个 NALU 是 PPS（图像参数集Picture Parameter Set）
对应H264标准文档 7.3.2.2 序列参数集的语法进行解析

PPS参数解析

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1. int InterpretPPS (VideoParameters *p_Vid, DataPartition *p, pic_parameter_set_rbsp_t *pps)  
2. {  
3.   unsigned i;  
4.   unsigned n_ScalingList;  
5.   int chroma_format_idc;  
6.   int NumberBitsPerSliceGroupId;  
7.   Bitstream *s = p->bitstream;  
8.   
9.   assert (p != NULL);  
10.   assert (p->bitstream != NULL);  
11.   assert (p->bitstream->streamBuffer != 0);  
12.   assert (pps != NULL);  
13.   
14.   p_Dec->UsedBits = 0;  
15.   
16.   pps->pic_parameter_set_id                  = ue_v ("PPS: pic_parameter_set_id"                   , s);  
17.   pps->seq_parameter_set_id                  = ue_v ("PPS: seq_parameter_set_id"                   , s);  
18.   pps->entropy_coding_mode_flag              = u_1  ("PPS: entropy_coding_mode_flag"               , s);  
19.   
20.   //! Note: as per JVT-F078 the following bit is unconditional.  If F078 is not accepted, then  
21.   //! one has to fetch the correct SPS to check whether the bit is present (hopefully there is  
22.   //! no consistency problem :-(  
23.   //! The current encoder code handles this in the same way.  When you change this, don't forget  
24.   //! the encoder!  StW, 12/8/02  
25.   pps->bottom_field_pic_order_in_frame_present_flag                = u_1  ("PPS: bottom_field_pic_order_in_frame_present_flag"                 , s);  
26.   
27.   pps->num_slice_groups_minus1               = ue_v ("PPS: num_slice_groups_minus1"                , s);  
28.   
29.   // FMO stuff begins here  
30.   if (pps->num_slice_groups_minus1 > 0)  
31.   {  
32.     pps->slice_group_map_type               = ue_v ("PPS: slice_group_map_type"                , s);  
33.     if (pps->slice_group_map_type == 0)  
34.     {  
35.       for (i=0; i<=pps->num_slice_groups_minus1; i++)  
36.         pps->run_length_minus1 [i]                  = ue_v ("PPS: run_length_minus1 [i]"              , s);  
37.     }  
38.     else if (pps->slice_group_map_type == 2)  
39.     {  
40.       for (i=0; inum_slice_groups_minus1; i++)  
41.       {  
42.         //! JVT-F078: avoid reference of SPS by using ue(v) instead of u(v)  
43.         pps->top_left [i]                          = ue_v ("PPS: top_left [i]"                        , s);  
44.         pps->bottom_right [i]                      = ue_v ("PPS: bottom_right [i]"                    , s);  
45.       }  
46.     }  
47.     else if (pps->slice_group_map_type == 3 ||  
48.              pps->slice_group_map_type == 4 ||  
49.              pps->slice_group_map_type == 5)  
50.     {  
51.       pps->slice_group_change_direction_flag     = u_1  ("PPS: slice_group_change_direction_flag"      , s);  
52.       pps->slice_group_change_rate_minus1        = ue_v ("PPS: slice_group_change_rate_minus1"         , s);  
53.     }  
54.     else if (pps->slice_group_map_type == 6)  
55.     {  
56.       if (pps->num_slice_groups_minus1+1 >4)  
57.         NumberBitsPerSliceGroupId = 3;  
58.       else if (pps->num_slice_groups_minus1+1 > 2)  
59.         NumberBitsPerSliceGroupId = 2;  
60.       else  
61.         NumberBitsPerSliceGroupId = 1;  
62.       pps->pic_size_in_map_units_minus1      = ue_v ("PPS: pic_size_in_map_units_minus1"               , s);  
63.       if ((pps->slice_group_id = calloc (pps->pic_size_in_map_units_minus1+1, 1)) == NULL)  
64.         no_mem_exit ("InterpretPPS: slice_group_id");  
65.       for (i=0; i<=pps->pic_size_in_map_units_minus1; i++)  
66.         pps->slice_group_id[i] = (byte) u_v (NumberBitsPerSliceGroupId, "slice_group_id[i]", s);  
67.     }  
68.   }  
69.   
70.   // End of FMO stuff  
71.   
72.   pps->num_ref_idx_l0_active_minus1          = ue_v ("PPS: num_ref_idx_l0_active_minus1"           , s);  
73.   pps->num_ref_idx_l1_active_minus1          = ue_v ("PPS: num_ref_idx_l1_active_minus1"           , s);  
74.   pps->weighted_pred_flag                    = u_1  ("PPS: weighted_pred_flag"                     , s);  
75.   pps->weighted_bipred_idc                   = u_v  ( 2, "PPS: weighted_bipred_idc"                , s);  
76.   pps->pic_init_qp_minus26                   = se_v ("PPS: pic_init_qp_minus26"                    , s);  
77.   pps->pic_init_qs_minus26                   = se_v ("PPS: pic_init_qs_minus26"                    , s);  
78.   
79.   pps->chroma_qp_index_offset                = se_v ("PPS: chroma_qp_index_offset"                 , s);  
80.   
81.   pps->deblocking_filter_control_present_flag = u_1 ("PPS: deblocking_filter_control_present_flag" , s);  
82.   pps->constrained_intra_pred_flag           = u_1  ("PPS: constrained_intra_pred_flag"            , s);  
83.   pps->redundant_pic_cnt_present_flag        = u_1  ("PPS: redundant_pic_cnt_present_flag"         , s);  
84.   
85.   if(more_rbsp_data(s->streamBuffer, s->frame_bitoffset,s->bitstream_length)) // more_data_in_rbsp()  
86.   {  
87.     //Fidelity Range Extensions Stuff  
88.     pps->transform_8x8_mode_flag           = u_1  ("PPS: transform_8x8_mode_flag"                , s);  
89.     pps->pic_scaling_matrix_present_flag   =  u_1  ("PPS: pic_scaling_matrix_present_flag"        , s);  
90.   
91.     if(pps->pic_scaling_matrix_present_flag)  
92.     {  
93.       chroma_format_idc = p_Vid->SeqParSet[pps->seq_parameter_set_id].chroma_format_idc;  
94.       n_ScalingList = 6 + ((chroma_format_idc != YUV444) ? 2 : 6) * pps->transform_8x8_mode_flag;  
95.       for(i=0; ipic_scaling_list_present_flag[i]= u_1  ("PPS: pic_scaling_list_present_flag"          , s);  
96.   
97.         if(pps->pic_scaling_list_present_flag[i])  
98.         {  
99.           if(i<6) scaling_list="">ScalingList4x4[i], 16, &pps->UseDefaultScalingMatrix4x4Flag[i], s);  
100.           else  
101.             Scaling_List(pps->ScalingList8x8[i-6], 64, &pps->UseDefaultScalingMatrix8x8Flag[i-6], s);  
102.         }  
103.       }  
104.     }  
105.     pps->second_chroma_qp_index_offset      = se_v ("PPS: second_chroma_qp_index_offset"          , s);  
106.   }  
107.   else  
108.   {  
109.     pps->second_chroma_qp_index_offset      = pps->chroma_qp_index_offset;  
110.   }  
111.   
112.   pps->Valid = TRUE;  
113.   return p_Dec->UsedBits;  
114. }  

H.264码流第三个 NALU 是 IDR（即时解码器刷新）
对应H264标准文档 7.3.3 序列参数集的语法进行解析

IDR参数解析

[cpp] view plain copy

 

1. case NALU_TYPE_IDR:  
2.         img->idr_flag = (nalu->nal_unit_type == NALU_TYPE_IDR);  
3.         img->nal_reference_idc = nalu->nal_reference_idc;  
4.         img->disposable_flag = (nalu->nal_reference_idc == NALU_PRIORITY_DISPOSABLE);  
5.         currSlice->dp_mode = PAR_DP_1;   //++ dp_mode：数据分割模式；PAR_DP_1=0：没有数据分割  
6.         currSlice->max_part_nr = 1;  
7.         currSlice->ei_flag = 0;  //++ 该处赋值直接影响decode_slice()函数中对decode_one_slice()函数的调用  
8.                                     //++ 该值不为0，表明当前片出错，解码程序将忽略当前片的解码过程，而使用错误隐藏  
9.         currStream = currSlice->partArr[0].bitstream;  
10.         currStream->ei_flag = 0; //++ 此处的赋值为最终赋值，以后不再改变。该值将对每个宏块的ei_flag产生影响  
11.                                     //++ 参见macroblock.c文件read_one_macroblock()函数的如下语句：  
12.                                     //++        :if(!dP->bitstream->ei_flag)      :currMB->ei_flag = 0;  
13.                                     //++ 该值还在macroblock.c文件if(IS_INTRA (currMB) && dP->bitstream->ei_flag && img->number)中用到  
14.         currStream->frame_bitoffset = currStream->read_len = 0;  
15.         memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);  
16.         currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1);  
17.   
18.         // Some syntax of the Slice Header depends on the parameter set, which depends on  
19.         // the parameter set ID of the SLice header.  Hence, read the pic_parameter_set_id  
20.         // of the slice header first, then setup the active parameter sets, and then read  
21.         // the rest of the slice header  
22.         BitsUsedByHeader = FirstPartOfSliceHeader();    //++ 参见标准7.3.3  
23.         UseParameterSet (currSlice->pic_parameter_set_id);  
24.         BitsUsedByHeader+= RestOfSliceHeader ();    //++ 参见标准7.3.3  
25.         //++ BitsUsedByHeader在程序中没有实际用处，而且BitsUsedByHeader+= RestOfSliceHeader ()  
26.         //++ 重复计算了FirstPartOfSliceHeader()所用到的比特数。因为在FirstPartOfSliceHeader()  
27.         //++ 之后，变量UsedBits值并未被置零就代入RestOfSliceHeader()运算，从而RestOfSliceHeader ()  
28.         //++ 在返回时，BitsUsedByHeader+= RestOfSliceHeader()多加了一个BitsUsedByHeader值  
29.   
30.         FmoInit (active_pps, active_sps);  
31.   
32.         if(is_new_picture())  
33.         {  
34.           init_picture(img, input);  
35.             
36.           current_header = SOP;  
37.           //check zero_byte if it is also the first NAL unit in the access unit  
38.           CheckZeroByteVCL(nalu, &ret);  
39.         }  
40.         else  
41.           current_header = SOS;  
42.     
43.         init_lists(img->type, img->currentSlice->structure);  
44.         reorder_lists (img->type, img->currentSlice);  
45.   
46.         if (img->structure==FRAME)  
47.         {  
48.           init_mbaff_lists();  
49.         }  
50.   
51. /*        if (img->frame_num==1) // write a reference list 
52.         { 
53.           count ++; 
54.           if (count==1) 
55.             for (i=0; i 
56.  
57.         // From here on, active_sps, active_pps and the slice header are valid 
58.         if (img->MbaffFrameFlag) 
59.           img->current_mb_nr = currSlice->start_mb_nr << 1="" style="color: #0000ff">else 
60.           img->current_mb_nr = currSlice->start_mb_nr; 
61.  
62.         if (active_pps->entropy_coding_mode_flag) 
63.         { 
64.           int ByteStartPosition = currStream->frame_bitoffset/8; 
65.           if (currStream->frame_bitoffset%8 != 0)  
66.           { 
67.             ByteStartPosition++; 
68.           } 
69.           arideco_start_decoding (&currSlice->partArr[0].de_cabac, currStream->streamBuffer, ByteStartPosition, &currStream->read_len, img->type); 
70.         } 
71. // printf ("read_new_slice: returning %s/n", current_header == SOP?"SOP":"SOS"); 
72.         FreeNALU(nalu); 
73.         return current_header; 
74.         break; 
75.       case NALU_TYPE_DPA: 
76.         //! The state machine here should follow the same ideas as the old readSliceRTP() 
77.         //! basically: 
78.         //! work on DPA (as above) 
79.         //! read and process all following SEI/SPS/PPS/PD/Filler NALUs 
80.         //! if next video NALU is dpB,  
81.         //!   then read and check whether it belongs to DPA, if yes, use it 
82.         //! else 
83.         //!   ;   // nothing 
84.         //! read and process all following SEI/SPS/PPS/PD/Filler NALUs 
85.         //! if next video NALU is dpC 
86.         //!   then read and check whether it belongs to DPA (and DPB, if present), if yes, use it, done 
87.         //! else 
88.         //!   use the DPA (and the DPB if present) 
89.  
90.         /*  
91.             LC: inserting the code related to DP processing, mainly copying some of the parts 
92.             related to NALU_TYPE_SLICE, NALU_TYPE_IDR. 
93.         */  
94.   
95.         if(expected_slice_type != NALU_TYPE_DPA)  
96.         {  
97.           /* oops... we found the next slice, go back! */  
98.           fseek(bits, ftell_position, SEEK_SET);  
99.           FreeNALU(nalu);  
100.           return current_header;  
101.         }  
102.   
103.         img->idr_flag          = (nalu->nal_unit_type == NALU_TYPE_IDR);  
104.         img->nal_reference_idc = nalu->nal_reference_idc;  
105.         img->disposable_flag   = (nalu->nal_reference_idc == NALU_PRIORITY_DISPOSABLE);  
106.         currSlice->dp_mode     = PAR_DP_3;  
107.         currSlice->max_part_nr = 3;  
108.         currSlice->ei_flag     = 0;  
109.         currStream             = currSlice->partArr[0].bitstream;  
110.         currStream->ei_flag    = 0;  
111.         currStream->frame_bitoffset = currStream->read_len = 0;  
112.         memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);  
113.         currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1);    //++ 剔除停止比特和填充比特  
114.           
115.         BitsUsedByHeader     = FirstPartOfSliceHeader();  
116.         UseParameterSet (currSlice->pic_parameter_set_id);  
117.         BitsUsedByHeader    += RestOfSliceHeader ();  
118.           
119.         FmoInit (active_pps, active_sps);  
120.   
121.         if(is_new_picture())  
122.         {  
123.           init_picture(img, input);  
124.           current_header = SOP;  
125.           CheckZeroByteVCL(nalu, &ret);  
126.         }  
127.         else  
128.           current_header = SOS;  
129.   
130.           
131.         init_lists(img->type, img->currentSlice->structure);  
132.         reorder_lists (img->type, img->currentSlice);  
133.           
134.         if (img->structure==FRAME)  
135.         {  
136.           init_mbaff_lists();  
137.         }  
138.   
139.         // From here on, active_sps, active_pps and the slice header are valid  
140.         if (img->MbaffFrameFlag)  
141.           img->current_mb_nr = currSlice->start_mb_nr << 1="" style="color: #0000ff">else  
142.    
143.          img->current_mb_nr = currSlice->start_mb_nr;  
144.   
145.   
146.         /*  
147.            LC: 
148.               Now I need to read the slice ID, which depends on the value of  
149.               redundant_pic_cnt_present_flag (pag.49).  
150.         */  
151.   
152.         slice_id_a  = ue_v("NALU:SLICE_A slice_idr", currStream);  
153.         if (active_pps->entropy_coding_mode_flag)  
154.         {  
155.           int ByteStartPosition = currStream->frame_bitoffset/8;  
156.           if (currStream->frame_bitoffset%8 != 0)   
157.           {  
158.             ByteStartPosition++;  
159.           }  
160.           arideco_start_decoding (&currSlice->partArr[0].de_cabac, currStream->streamBuffer, ByteStartPosition, &currStream->read_len, img->type);  
161.         }  
162. // printf ("read_new_slice: returning %s/n", current_header == SOP?"SOP":"SOS");  
163.         break;  
164.       case NALU_TYPE_DPB:  
165.         /* LC: inserting the code related to DP processing */  
166.   
167.         currStream             = currSlice->partArr[1].bitstream;  
168.         currStream->ei_flag    = 0;  
169.         currStream->frame_bitoffset = currStream->read_len = 0;  
170.         memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);  
171.         currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1);  
172.   
173.         slice_id_b  = ue_v("NALU:SLICE_B slice_idr", currStream);  
174.         if (active_pps->redundant_pic_cnt_present_flag)  
175.           redundant_pic_cnt_b = ue_v("NALU:SLICE_B redudand_pic_cnt", currStream);  
176.         else  
177.           redundant_pic_cnt_b = 0;  
178.           
179.         /*  LC: Initializing CABAC for the current data stream. */  
180.   
181.         if (active_pps->entropy_coding_mode_flag)  
182.         {  
183.           int ByteStartPosition = currStream->frame_bitoffset/8;  
184.           if (currStream->frame_bitoffset % 8 != 0)   
185.             ByteStartPosition++;  
186.             
187.           arideco_start_decoding (&currSlice->partArr[1].de_cabac, currStream->streamBuffer,   
188.             ByteStartPosition, &currStream->read_len, img->type);  
189.             
190.         }  
191.   
192.         /* LC: resilience code to be inserted */  
193.         /*         FreeNALU(nalu); */  
194.         /*         return current_header; */  
195.   
196.         break;  

IDR参数解析/*!

[cpp] view plain copy

 

1. <pre name="code" class="cpp"> ************************************************************************  
2.  * /brief  
3.  *    read the first part of the header (only the pic_parameter_set_id)  
4.  * /return  
5.  *    Length of the first part of the slice header (in bits)  
6.  ************************************************************************  
7.  */  
8. //++ 参见标准7.3.3  
9. int FirstPartOfSliceHeader()  
10. {  
11.   Slice *currSlice = img->currentSlice;  
12.   int dP_nr = assignSE2partition[currSlice->dp_mode][SE_HEADER];  
13.   DataPartition *partition = &(currSlice->partArr[dP_nr]);  
14.   Bitstream *currStream = partition->bitstream;  
15.   int tmp;  
16.   
17.   UsedBits= partition->bitstream->frame_bitoffset; // was hardcoded to 31 for previous start-code. This is better.  
18.   
19.   // Get first_mb_in_slice  
20.   currSlice->start_mb_nr = ue_v ("SH: first_mb_in_slice", currStream);  
21.   
22.   tmp = ue_v ("SH: slice_type", currStream);  
23.     
24.   if (tmp>4) tmp -=5;  
25.   
26.   img->type = currSlice->picture_type = (SliceType) tmp;  
27.   
28.   currSlice->pic_parameter_set_id = ue_v ("SH: pic_parameter_set_id", currStream);  
29.     
30.   return UsedBits;  
31. }  
32. </pre><br><br>