h265 Nalu类型判断及 sps 数据解析

来源：互联网发布：电脑修复软件编辑：程序博客网时间：2024/06/05 21:15

一，Nalu解析

首先来介绍下h265（HEVC）nal单元头，与h264的nal层相比，h265的nal unit header有两个字节构成，如下图所示

0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+ -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| F | Type | LayerId | TID |
+------------ - +---------------- - +

其语法如下表中的定义：

nal_unit_header( ) {

Descriptor

forbidden_zero_bit

f(1)

nal_unit_type

u(6)

nuh_reserved_zero_6bits

u(6)

nuh_temporal_id_plus1

u(3)

}

从图中可以看出hHEVC的nal包结构与h264有明显的不同，hevc加入了nal所在的时间层的ＩＤ，取去除了nal_ref_idc，此信息合并到了naltype中，

通常情况下F为0，layerid为0, TID为1。

H265 帧类型判断：

和264的&0x1f不同。265是 :
int type = (code & 0x7E)>>1;

在文件中查找00 00 00 01NALU头，发现在有6种开头分别为：

再根据H265的NALU类型定义分析，

00 00 00 01 40 01 的nuh_unit_type的值为 32，语义为视频参数集 VPS

00 00 00 01 42 01 的nuh_unit_type的值为 33，语义为序列参数集 SPS

00 00 00 01 44 01 的nuh_unit_type的值为 34，语义为图像参数集 PPS

00 00 00 01 4E 01 的nuh_unit_type的值为 39，语义为补充增强信息 SEI

00 00 00 01 26 01 的nuh_unit_type的值为 19，语义为可能有RADL图像的IDR图像的SS编码数据 IDR

00 00 00 01 02 01 的nuh_unit_type的值为1，语义为被参考的后置图像，且非TSA、非STSA的SS编码数据

在编码过程中，从编码器获取码流的时候，1、2、3、4、5是在一帧数据当中。相当于H264的I帧。

Nalu Type的定义

enum NalUnitType
{
NAL_UNIT_CODED_SLICE_TRAIL_N = 0, // 0
NAL_UNIT_CODED_SLICE_TRAIL_R, // 1
NAL_UNIT_CODED_SLICE_TSA_N, // 2
NAL_UNIT_CODED_SLICE_TLA, // 3 // Current name in the spec: TSA_R
NAL_UNIT_CODED_SLICE_STSA_N, // 4
NAL_UNIT_CODED_SLICE_STSA_R, // 5
NAL_UNIT_CODED_SLICE_RADL_N, // 6
NAL_UNIT_CODED_SLICE_DLP, // 7 // Current name in the spec: RADL_R
NAL_UNIT_CODED_SLICE_RASL_N, // 8
NAL_UNIT_CODED_SLICE_TFD, // 9 // Current name in the spec: RASL_R
NAL_UNIT_RESERVED_10,
NAL_UNIT_RESERVED_11,
NAL_UNIT_RESERVED_12,
NAL_UNIT_RESERVED_13,
NAL_UNIT_RESERVED_14,
NAL_UNIT_RESERVED_15, NAL_UNIT_CODED_SLICE_BLA, // 16 // Current name in the spec: BLA_W_LP
NAL_UNIT_CODED_SLICE_BLA, // 16 // Current name in the spec: BLA_W_LP
NAL_UNIT_CODED_SLICE_BLANT, // 17 // Current name in the spec: BLA_W_DLP
NAL_UNIT_CODED_SLICE_BLA_N_LP, // 18
NAL_UNIT_CODED_SLICE_IDR, // 19 // Current name in the spec: IDR_W_DLP
NAL_UNIT_CODED_SLICE_IDR_N_LP, // 20
NAL_UNIT_CODED_SLICE_CRA, // 21
NAL_UNIT_RESERVED_22,
NAL_UNIT_RESERVED_23,
NAL_UNIT_RESERVED_24,
NAL_UNIT_RESERVED_25,
NAL_UNIT_RESERVED_26,
NAL_UNIT_RESERVED_27,
NAL_UNIT_RESERVED_28,
NAL_UNIT_RESERVED_29,
NAL_UNIT_RESERVED_30,
NAL_UNIT_RESERVED_31,
NAL_UNIT_VPS, // 32
NAL_UNIT_SPS, // 33
NAL_UNIT_PPS, // 34
NAL_UNIT_ACCESS_UNIT_DELIMITER, // 35
NAL_UNIT_EOS, // 36
NAL_UNIT_EOB, // 37
NAL_UNIT_FILLER_DATA, // 38
NAL_UNIT_SEI, // 39 Prefix SEI
NAL_UNIT_SEI_SUFFIX, // 40 Suffix SEI
NAL_UNIT_RESERVED_41,
NAL_UNIT_RESERVED_42,
NAL_UNIT_RESERVED_43,
NAL_UNIT_RESERVED_44,
NAL_UNIT_RESERVED_45,
NAL_UNIT_RESERVED_46,
NAL_UNIT_RESERVED_47,
NAL_UNIT_UNSPECIFIED_48,
NAL_UNIT_UNSPECIFIED_49,
NAL_UNIT_UNSPECIFIED_50,
NAL_UNIT_UNSPECIFIED_51,
NAL_UNIT_UNSPECIFIED_52,
NAL_UNIT_UNSPECIFIED_53,
NAL_UNIT_UNSPECIFIED_54,
NAL_UNIT_UNSPECIFIED_55,
NAL_UNIT_UNSPECIFIED_56,
NAL_UNIT_UNSPECIFIED_57,
NAL_UNIT_UNSPECIFIED_58,
NAL_UNIT_UNSPECIFIED_59,
NAL_UNIT_UNSPECIFIED_60,
NAL_UNIT_UNSPECIFIED_61,
NAL_UNIT_UNSPECIFIED_62,
NAL_UNIT_UNSPECIFIED_63,
NAL_UNIT_INVALID,
};

二， SPS解析

1、重新定义类型

typedef unsigned char uint8;

typedef unsigned short uint16;

typedef unsigned longuint32;
typedef unsigned __int64uint64;
typedef signed charint8;
typedef signed shortint16;
typedef signed longint32;
typedef signed __int64int64;

2、定义Sps 需要的相关参数

struct vc_params_t{LONG width,height;DWORD profile, level;DWORD nal_length_size;void clear(){memset(this, 0, sizeof(*this));}};

3、定义网络抽象层Nal类

 class NALBitstream { public: NALBitstream() : m_data(NULL), m_len(0), m_idx(0), m_bits(0), m_byte(0), m_zeros(0)  { }; NALBitstream(void * data, int len)  { Init(data, len);  }; void Init(void * data, int len)  { m_data = (LPBYTE)data; m_len = len; m_idx = 0;  m_bits = 0; m_byte = 0;  m_zeros = 0;  }; BYTE GetBYTE() { if ( m_idx >= m_len ) return 0; BYTE b = m_data[m_idx++]; if ( b == 0 ) { m_zeros++; if ( (m_idx < m_len) && (m_zeros == 2) && (m_data[m_idx] == 0x03) ) { m_idx++; m_zeros=0; } }  else  m_zeros = 0; return b; }; UINT32 GetBit()  { if (m_bits == 0)  { m_byte = GetBYTE(); m_bits = 8; } m_bits--; return (m_byte >> m_bits) & 0x1; }; UINT32 GetWord(int bits)  { UINT32 u = 0; while ( bits > 0 ) { u <<= 1; u |= GetBit(); bits--; } return u; }; UINT32 GetUE()  { int zeros = 0; while (m_idx < m_len && GetBit() == 0 ) zeros++; return GetWord(zeros) + ((1 << zeros) - 1); }; INT32 GetSE() { UINT32 UE = GetUE(); bool positive = UE & 1; INT32 SE = (UE + 1) >> 1; if ( !positive ) { SE = -SE; } return SE; }; private: LPBYTE m_data; int m_len; int m_idx; int m_bits; BYTE m_byte; int m_zeros; }; bool  ParseSequenceParameterSet(BYTE* data,int size, vc_params_t& params) { if (size < 20) {  return false; } NALBitstream bs(data, size); // seq_parameter_set_rbsp() bs.GetWord(4);// sps_video_parameter_set_id int sps_max_sub_layers_minus1 = bs.GetWord(3);  if (sps_max_sub_layers_minus1 > 6)  { return false; } bs.GetWord(1);  { bs.GetWord(2);  bs.GetWord(1);  params.profile = bs.GetWord(5);  bs.GetWord(32);// bs.GetWord(1);//  bs.GetWord(1);//  bs.GetWord(1);//  bs.GetWord(1);//   bs.GetWord(44);//  params.level   = bs.GetWord(8);// general_level_idc uint8 sub_layer_profile_present_flag[6] = {0}; uint8 sub_layer_level_present_flag[6]   = {0}; for (int i = 0; i < sps_max_sub_layers_minus1; i++) { sub_layer_profile_present_flag[i]= bs.GetWord(1); sub_layer_level_present_flag[i]= bs.GetWord(1); } if (sps_max_sub_layers_minus1 > 0)  { for (int i = sps_max_sub_layers_minus1; i < 8; i++) { uint8 reserved_zero_2bits = bs.GetWord(2); } } for (int i = 0; i < sps_max_sub_layers_minus1; i++)  { if (sub_layer_profile_present_flag[i]) { bs.GetWord(2);  bs.GetWord(1);  bs.GetWord(5);/  bs.GetWord(32);  bs.GetWord(1);  bs.GetWord(1);  bs.GetWord(1);  bs.GetWord(1);  bs.GetWord(44);  } if (sub_layer_level_present_flag[i]) { bs.GetWord(8);// sub_layer_level_idc[i] } } } uint32 sps_seq_parameter_set_id= bs.GetUE();   if (sps_seq_parameter_set_id > 15) { return false; } uint32 chroma_format_idc = bs.GetUE();   if (sps_seq_parameter_set_id > 3) { return false; } if (chroma_format_idc == 3) { bs.GetWord(1);//   } params.width  = bs.GetUE(); // pic_width_in_luma_samples params.height  = bs.GetUE(); // pic_height_in_luma_samples if (bs.GetWord(1)) {  bs.GetUE();   bs.GetUE();   bs.GetUE();   bs.GetUE();    } uint32 bit_depth_luma_minus8= bs.GetUE(); uint32 bit_depth_chroma_minus8= bs.GetUE(); if (bit_depth_luma_minus8 != bit_depth_chroma_minus8) { return false; } //... return true; }

4、测试代码

 int _tmain(int argc, _TCHAR* argv[])   {   vc_params_t params = {0};   BYTE Sps[41] = {0X42,0X01,0X01,0X01,0X60,0X00,0X00,0X03,0X00,0X80,0X00,0X00,0X03,0X00,0X00,

  0X03,0X00,0X5D,0XA0,0X02,0X80, 0X80,0X2D,0X16,0X59,0X5E,0X49,0X32,0XB8,0X04,0X00,0X00,0X03,

  0X00,0X04,0X00,0X00,0X03,0X00,0X64,0X20};

 ParseSequenceParameterSet(Sps,41,params);   printf("%d-%d-%d\n",params.width,params.height,params.level);   system("pause");   return 0;   }

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