嵌入式 H264参数语法文档： SPS、PPS、IDR以及NALU编码规律

本文主要是介绍嵌入式 H264参数语法文档： SPS、PPS、IDR以及NALU编码规律，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

// 【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

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SPS参数解析// fill sps with content of p

[cpp] view plaincopy

int InterpretSPS (VideoParameters *p_Vid, DataPartition *p, seq_parameter_set_rbsp_t *sps)
{
unsigned i;
unsigned n_ScalingList;
int reserved_zero;
Bitstream *s = p->bitstream;
assert (p != NULL);
assert (p->bitstream != NULL);
assert (p->bitstream->streamBuffer != 0);
assert (sps != NULL);
p_Dec->UsedBits = 0;
sps->profile_idc = u_v (8, "SPS: profile_idc" , s);
if ((sps->profile_idc!=BASELINE ) &&
(sps->profile_idc!=MAIN ) &&
(sps->profile_idc!=EXTENDED ) &&
(sps->profile_idc!=FREXT_HP ) &&
(sps->profile_idc!=FREXT_Hi10P ) &&
(sps->profile_idc!=FREXT_Hi422 ) &&
(sps->profile_idc!=FREXT_Hi444 ) &&
(sps->profile_idc!=FREXT_CAVLC444 )
#if (MVC_EXTENSION_ENABLE)
&& (sps->profile_idc!=MVC_HIGH)
&& (sps->profile_idc!=STEREO_HIGH)
#endif
)
{
printf("Invalid Profile IDC (%d) encountered. /n", sps->profile_idc);
return p_Dec->UsedBits;
}
sps->constrained_set0_flag = u_1 ( "SPS: constrained_set0_flag" , s);
sps->constrained_set1_flag = u_1 ( "SPS: constrained_set1_flag" , s);
sps->constrained_set2_flag = u_1 ( "SPS: constrained_set2_flag" , s);
sps->constrained_set3_flag = u_1 ( "SPS: constrained_set3_flag" , s);
#if (MVC_EXTENSION_ENABLE)
sps->constrained_set4_flag = u_1 ( "SPS: constrained_set4_flag" , s);
reserved_zero = u_v (3, "SPS: reserved_zero_3bits" , s);
#else
reserved_zero = u_v (4, "SPS: reserved_zero_4bits" , s);
#endif
assert (reserved_zero==0);
sps->level_idc = u_v (8, "SPS: level_idc" , s);
sps->seq_parameter_set_id = ue_v ("SPS: seq_parameter_set_id" , s);
// Fidelity Range Extensions stuff
sps->chroma_format_idc = 1;
sps->bit_depth_luma_minus8 = 0;
sps->bit_depth_chroma_minus8 = 0;
p_Vid->lossless_qpprime_flag = 0;
sps->separate_colour_plane_flag = 0;
if((sps->profile_idc==FREXT_HP ) ||
(sps->profile_idc==FREXT_Hi10P) ||
(sps->profile_idc==FREXT_Hi422) ||
(sps->profile_idc==FREXT_Hi444) ||
(sps->profile_idc==FREXT_CAVLC444)
#if (MVC_EXTENSION_ENABLE)
|| (sps->profile_idc==MVC_HIGH)
|| (sps->profile_idc==STEREO_HIGH)
#endif
)
{
sps->chroma_format_idc = ue_v ("SPS: chroma_format_idc" , s);
if(sps->chroma_format_idc == YUV444)
{
sps->separate_colour_plane_flag = u_1 ("SPS: separate_colour_plane_flag" , s);
}
sps->bit_depth_luma_minus8 = ue_v ("SPS: bit_depth_luma_minus8" , s);
sps->bit_depth_chroma_minus8 = ue_v ("SPS: bit_depth_chroma_minus8" , s);
//checking;
if((sps->bit_depth_luma_minus8+8 > sizeof(imgpel)*8) || (sps->bit_depth_chroma_minus8+8> sizeof(imgpel)*8))
error ("Source picture has higher bit depth than imgpel data type. /nPlease recompile with larger data type for imgpel.", 500);
p_Vid->lossless_qpprime_flag = u_1 ("SPS: lossless_qpprime_y_zero_flag" , s);
sps->seq_scaling_matrix_present_flag = u_1 ( "SPS: seq_scaling_matrix_present_flag" , s);
if(sps->seq_scaling_matrix_present_flag)
{
n_ScalingList = (sps->chroma_format_idc != YUV444) ? 8 : 12;
for(i=0; iseq_scaling_list_present_flag[i] = u_1 ( "SPS: seq_scaling_list_present_flag" , s);
if(sps->seq_scaling_list_present_flag[i])
{
if(i<6) scaling_list="">ScalingList4x4[i], 16, &sps->UseDefaultScalingMatrix4x4Flag[i], s);
else
Scaling_List(sps->ScalingList8x8[i-6], 64, &sps->UseDefaultScalingMatrix8x8Flag[i-6], s);
}
}
}
}
sps->log2_max_frame_num_minus4 = ue_v ("SPS: log2_max_frame_num_minus4" , s);
sps->pic_order_cnt_type = ue_v ("SPS: pic_order_cnt_type" , s);
if (sps->pic_order_cnt_type == 0)
sps->log2_max_pic_order_cnt_lsb_minus4 = ue_v ("SPS: log2_max_pic_order_cnt_lsb_minus4" , s);
else if (sps->pic_order_cnt_type == 1)
{
sps->delta_pic_order_always_zero_flag = u_1 ("SPS: delta_pic_order_always_zero_flag" , s);
sps->offset_for_non_ref_pic = se_v ("SPS: offset_for_non_ref_pic" , s);
sps->offset_for_top_to_bottom_field = se_v ("SPS: offset_for_top_to_bottom_field" , s);
sps->num_ref_frames_in_pic_order_cnt_cycle = ue_v ("SPS: num_ref_frames_in_pic_order_cnt_cycle" , s);
for(i=0; inum_ref_frames_in_pic_order_cnt_cycle; i++)
sps->offset_for_ref_frame[i] = se_v ("SPS: offset_for_ref_frame[i]" , s);
}
sps->num_ref_frames = ue_v ("SPS: num_ref_frames" , s);
sps->gaps_in_frame_num_value_allowed_flag = u_1 ("SPS: gaps_in_frame_num_value_allowed_flag" , s);
sps->pic_width_in_mbs_minus1 = ue_v ("SPS: pic_width_in_mbs_minus1" , s);
sps->pic_height_in_map_units_minus1 = ue_v ("SPS: pic_height_in_map_units_minus1" , s);
sps->frame_mbs_only_flag = u_1 ("SPS: frame_mbs_only_flag" , s);
if (!sps->frame_mbs_only_flag)
{
sps->mb_adaptive_frame_field_flag = u_1 ("SPS: mb_adaptive_frame_field_flag" , s);
}
sps->direct_8x8_inference_flag = u_1 ("SPS: direct_8x8_inference_flag" , s);
sps->frame_cropping_flag = u_1 ("SPS: frame_cropping_flag" , s);
if (sps->frame_cropping_flag)
{
sps->frame_cropping_rect_left_offset = ue_v ("SPS: frame_cropping_rect_left_offset" , s);
sps->frame_cropping_rect_right_offset = ue_v ("SPS: frame_cropping_rect_right_offset" , s);
sps->frame_cropping_rect_top_offset = ue_v ("SPS: frame_cropping_rect_top_offset" , s);
sps->frame_cropping_rect_bottom_offset = ue_v ("SPS: frame_cropping_rect_bottom_offset" , s);
}
sps->vui_parameters_present_flag = (Boolean) u_1 ("SPS: vui_parameters_present_flag" , s);
InitVUI(sps);
ReadVUI(p, sps);
sps->Valid = TRUE;
return p_Dec->UsedBits;
}

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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

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PPS参数解析

[cpp] view plaincopy

int InterpretPPS (VideoParameters *p_Vid, DataPartition *p, pic_parameter_set_rbsp_t *pps)
{
unsigned i;
unsigned n_ScalingList;
int chroma_format_idc;
int NumberBitsPerSliceGroupId;
Bitstream *s = p->bitstream;
assert (p != NULL);
assert (p->bitstream != NULL);
assert (p->bitstream->streamBuffer != 0);
assert (pps != NULL);
p_Dec->UsedBits = 0;
pps->pic_parameter_set_id = ue_v ("PPS: pic_parameter_set_id" , s);
pps->seq_parameter_set_id = ue_v ("PPS: seq_parameter_set_id" , s);
pps->entropy_coding_mode_flag = u_1 ("PPS: entropy_coding_mode_flag" , s);
//! Note: as per JVT-F078 the following bit is unconditional. If F078 is not accepted, then
//! one has to fetch the correct SPS to check whether the bit is present (hopefully there is
//! no consistency problem :-(
//! The current encoder code handles this in the same way. When you change this, don't forget
//! the encoder! StW, 12/8/02
pps->bottom_field_pic_order_in_frame_present_flag = u_1 ("PPS: bottom_field_pic_order_in_frame_present_flag" , s);
pps->num_slice_groups_minus1 = ue_v ("PPS: num_slice_groups_minus1" , s);
// FMO stuff begins here
if (pps->num_slice_groups_minus1 > 0)
{
pps->slice_group_map_type = ue_v ("PPS: slice_group_map_type" , s);
if (pps->slice_group_map_type == 0)
{
for (i=0; i<=pps->num_slice_groups_minus1; i++)
pps->run_length_minus1 [i] = ue_v ("PPS: run_length_minus1 [i]" , s);
}
else if (pps->slice_group_map_type == 2)
{
for (i=0; inum_slice_groups_minus1; i++)
{
//! JVT-F078: avoid reference of SPS by using ue(v) instead of u(v)
pps->top_left [i] = ue_v ("PPS: top_left [i]" , s);
pps->bottom_right [i] = ue_v ("PPS: bottom_right [i]" , s);
}
}
else if (pps->slice_group_map_type == 3 ||
pps->slice_group_map_type == 4 ||
pps->slice_group_map_type == 5)
{
pps->slice_group_change_direction_flag = u_1 ("PPS: slice_group_change_direction_flag" , s);
pps->slice_group_change_rate_minus1 = ue_v ("PPS: slice_group_change_rate_minus1" , s);
}
else if (pps->slice_group_map_type == 6)
{
if (pps->num_slice_groups_minus1+1 >4)
NumberBitsPerSliceGroupId = 3;
else if (pps->num_slice_groups_minus1+1 > 2)
NumberBitsPerSliceGroupId = 2;
else
NumberBitsPerSliceGroupId = 1;
pps->pic_size_in_map_units_minus1 = ue_v ("PPS: pic_size_in_map_units_minus1" , s);
if ((pps->slice_group_id = calloc (pps->pic_size_in_map_units_minus1+1, 1)) == NULL)
no_mem_exit ("InterpretPPS: slice_group_id");
for (i=0; i<=pps->pic_size_in_map_units_minus1; i++)
pps->slice_group_id[i] = (byte) u_v (NumberBitsPerSliceGroupId, "slice_group_id[i]", s);
}
}
// End of FMO stuff
pps->num_ref_idx_l0_active_minus1 = ue_v ("PPS: num_ref_idx_l0_active_minus1" , s);
pps->num_ref_idx_l1_active_minus1 = ue_v ("PPS: num_ref_idx_l1_active_minus1" , s);
pps->weighted_pred_flag = u_1 ("PPS: weighted_pred_flag" , s);
pps->weighted_bipred_idc = u_v ( 2, "PPS: weighted_bipred_idc" , s);
pps->pic_init_qp_minus26 = se_v ("PPS: pic_init_qp_minus26" , s);
pps->pic_init_qs_minus26 = se_v ("PPS: pic_init_qs_minus26" , s);
pps->chroma_qp_index_offset = se_v ("PPS: chroma_qp_index_offset" , s);
pps->deblocking_filter_control_present_flag = u_1 ("PPS: deblocking_filter_control_present_flag" , s);
pps->constrained_intra_pred_flag = u_1 ("PPS: constrained_intra_pred_flag" , s);
pps->redundant_pic_cnt_present_flag = u_1 ("PPS: redundant_pic_cnt_present_flag" , s);
if(more_rbsp_data(s->streamBuffer, s->frame_bitoffset,s->bitstream_length)) // more_data_in_rbsp()
{
//Fidelity Range Extensions Stuff
pps->transform_8x8_mode_flag = u_1 ("PPS: transform_8x8_mode_flag" , s);
pps->pic_scaling_matrix_present_flag = u_1 ("PPS: pic_scaling_matrix_present_flag" , s);
if(pps->pic_scaling_matrix_present_flag)
{
chroma_format_idc = p_Vid->SeqParSet[pps->seq_parameter_set_id].chroma_format_idc;
n_ScalingList = 6 + ((chroma_format_idc != YUV444) ? 2 : 6) * pps->transform_8x8_mode_flag;
for(i=0; ipic_scaling_list_present_flag[i]= u_1 ("PPS: pic_scaling_list_present_flag" , s);
if(pps->pic_scaling_list_present_flag[i])
{
if(i<6) scaling_list="">ScalingList4x4[i], 16, &pps->UseDefaultScalingMatrix4x4Flag[i], s);
else
Scaling_List(pps->ScalingList8x8[i-6], 64, &pps->UseDefaultScalingMatrix8x8Flag[i-6], s);
}
}
}
pps->second_chroma_qp_index_offset = se_v ("PPS: second_chroma_qp_index_offset" , s);
}
else
{
pps->second_chroma_qp_index_offset = pps->chroma_qp_index_offset;
}
pps->Valid = TRUE;
return p_Dec->UsedBits;
}

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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

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IDR参数解析

[cpp] view plaincopy

case NALU_TYPE_IDR:
img->idr_flag = (nalu->nal_unit_type == NALU_TYPE_IDR);
img->nal_reference_idc = nalu->nal_reference_idc;
img->disposable_flag = (nalu->nal_reference_idc == NALU_PRIORITY_DISPOSABLE);
currSlice->dp_mode = PAR_DP_1; //++ dp_mode：数据分割模式；PAR_DP_1=0：没有数据分割
currSlice->max_part_nr = 1;
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
//++ 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
currStream = currSlice->partArr[0].bitstream;
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
//++ 参见macroblock.c文件read_one_macroblock()函数的如下语句：
//++ :if(!dP->bitstream->ei_flag) :currMB->ei_flag = 0;
//++ 该值还在macroblock.c文件if(IS_INTRA (currMB) && dP->bitstream->ei_flag && img->number)中用到
currStream->frame_bitoffset = currStream->read_len = 0;
memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);
currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1);
// Some syntax of the Slice Header depends on the parameter set, which depends on
// the parameter set ID of the SLice header. Hence, read the pic_parameter_set_id
// of the slice header first, then setup the active parameter sets, and then read
// the rest of the slice header
BitsUsedByHeader = FirstPartOfSliceHeader(); //++ 参见标准7.3.3
UseParameterSet (currSlice->pic_parameter_set_id);
BitsUsedByHeader+= RestOfSliceHeader (); //++ 参见标准7.3.3
//++ BitsUsedByHeader在程序中没有实际用处，而且BitsUsedByHeader+= RestOfSliceHeader ()
//++ 重复计算了FirstPartOfSliceHeader()所用到的比特数。因为在FirstPartOfSliceHeader()
//++ 之后，变量UsedBits值并未被置零就代入RestOfSliceHeader()运算，从而RestOfSliceHeader ()
//++ 在返回时，BitsUsedByHeader+= RestOfSliceHeader()多加了一个BitsUsedByHeader值
FmoInit (active_pps, active_sps);
if(is_new_picture())
{
init_picture(img, input);
current_header = SOP;
//check zero_byte if it is also the first NAL unit in the access unit
CheckZeroByteVCL(nalu, &ret);
}
else
current_header = SOS;
init_lists(img->type, img->currentSlice->structure);
reorder_lists (img->type, img->currentSlice);
if (img->structure==FRAME)
{
init_mbaff_lists();
}
/* if (img->frame_num==1) // write a reference list
{
count ++;
if (count==1)
for (i=0; i
// From here on, active_sps, active_pps and the slice header are valid
if (img->MbaffFrameFlag)
img->current_mb_nr = currSlice->start_mb_nr << 1="" style="color: #0000ff">else
img->current_mb_nr = currSlice->start_mb_nr;
if (active_pps->entropy_coding_mode_flag)
{
int ByteStartPosition = currStream->frame_bitoffset/8;
if (currStream->frame_bitoffset%8 != 0)
{
ByteStartPosition++;
}
arideco_start_decoding (&currSlice->partArr[0].de_cabac, currStream->streamBuffer, ByteStartPosition, &currStream->read_len, img->type);
}
// printf ("read_new_slice: returning %s/n", current_header == SOP?"SOP":"SOS");
FreeNALU(nalu);
return current_header;
break;
case NALU_TYPE_DPA:
//! The state machine here should follow the same ideas as the old readSliceRTP()
//! basically:
//! work on DPA (as above)
//! read and process all following SEI/SPS/PPS/PD/Filler NALUs
//! if next video NALU is dpB,
//! then read and check whether it belongs to DPA, if yes, use it
//! else
//! ; // nothing
//! read and process all following SEI/SPS/PPS/PD/Filler NALUs
//! if next video NALU is dpC
//! then read and check whether it belongs to DPA (and DPB, if present), if yes, use it, done
//! else
//! use the DPA (and the DPB if present)
/*
LC: inserting the code related to DP processing, mainly copying some of the parts
related to NALU_TYPE_SLICE, NALU_TYPE_IDR.
*/
if(expected_slice_type != NALU_TYPE_DPA)
{
/* oops... we found the next slice, go back! */
fseek(bits, ftell_position, SEEK_SET);
FreeNALU(nalu);
return current_header;
}
img->idr_flag = (nalu->nal_unit_type == NALU_TYPE_IDR);
img->nal_reference_idc = nalu->nal_reference_idc;
img->disposable_flag = (nalu->nal_reference_idc == NALU_PRIORITY_DISPOSABLE);
currSlice->dp_mode = PAR_DP_3;
currSlice->max_part_nr = 3;
currSlice->ei_flag = 0;
currStream = currSlice->partArr[0].bitstream;
currStream->ei_flag = 0;
currStream->frame_bitoffset = currStream->read_len = 0;
memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);
currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1); //++ 剔除停止比特和填充比特
BitsUsedByHeader = FirstPartOfSliceHeader();
UseParameterSet (currSlice->pic_parameter_set_id);
BitsUsedByHeader += RestOfSliceHeader ();
FmoInit (active_pps, active_sps);
if(is_new_picture())
{
init_picture(img, input);
current_header = SOP;
CheckZeroByteVCL(nalu, &ret);
}
else
current_header = SOS;
init_lists(img->type, img->currentSlice->structure);
reorder_lists (img->type, img->currentSlice);
if (img->structure==FRAME)
{
init_mbaff_lists();
}
// From here on, active_sps, active_pps and the slice header are valid
if (img->MbaffFrameFlag)
img->current_mb_nr = currSlice->start_mb_nr << 1="" style="color: #0000ff">else
img->current_mb_nr = currSlice->start_mb_nr;
/*
LC:
Now I need to read the slice ID, which depends on the value of
redundant_pic_cnt_present_flag (pag.49).
*/
slice_id_a = ue_v("NALU:SLICE_A slice_idr", currStream);
if (active_pps->entropy_coding_mode_flag)
{
int ByteStartPosition = currStream->frame_bitoffset/8;
if (currStream->frame_bitoffset%8 != 0)
{
ByteStartPosition++;
}
arideco_start_decoding (&currSlice->partArr[0].de_cabac, currStream->streamBuffer, ByteStartPosition, &currStream->read_len, img->type);
}
// printf ("read_new_slice: returning %s/n", current_header == SOP?"SOP":"SOS");
break;
case NALU_TYPE_DPB:
/* LC: inserting the code related to DP processing */
currStream = currSlice->partArr[1].bitstream;
currStream->ei_flag = 0;
currStream->frame_bitoffset = currStream->read_len = 0;
memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);
currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1);
slice_id_b = ue_v("NALU:SLICE_B slice_idr", currStream);
if (active_pps->redundant_pic_cnt_present_flag)
redundant_pic_cnt_b = ue_v("NALU:SLICE_B redudand_pic_cnt", currStream);
else
redundant_pic_cnt_b = 0;
/* LC: Initializing CABAC for the current data stream. */
if (active_pps->entropy_coding_mode_flag)
{
int ByteStartPosition = currStream->frame_bitoffset/8;
if (currStream->frame_bitoffset % 8 != 0)
ByteStartPosition++;
arideco_start_decoding (&currSlice->partArr[1].de_cabac, currStream->streamBuffer,
ByteStartPosition, &currStream->read_len, img->type);
}
/* LC: resilience code to be inserted */
/* FreeNALU(nalu); */
/* return current_header; */
break;

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IDR参数解析/*!

[cpp] view plaincopy

<pre name="code" class="cpp"> ************************************************************************
* /brief
* read the first part of the header (only the pic_parameter_set_id)
* /return
* Length of the first part of the slice header (in bits)
************************************************************************
*/
//++ 参见标准7.3.3
int FirstPartOfSliceHeader()
{
Slice *currSlice = img->currentSlice;
int dP_nr = assignSE2partition[currSlice->dp_mode][SE_HEADER];
DataPartition *partition = &(currSlice->partArr[dP_nr]);
Bitstream *currStream = partition->bitstream;
int tmp;
UsedBits= partition->bitstream->frame_bitoffset; // was hardcoded to 31 for previous start-code. This is better.
// Get first_mb_in_slice
currSlice->start_mb_nr = ue_v ("SH: first_mb_in_slice", currStream);
tmp = ue_v ("SH: slice_type", currStream);
if (tmp>4) tmp -=5;
img->type = currSlice->picture_type = (SliceType) tmp;
currSlice->pic_parameter_set_id = ue_v ("SH: pic_parameter_set_id", currStream);
return UsedBits;
}
</pre><br><br>