h264解码之自定义信息（SEI）

阳光穿透心脏的1/2处 2022-11-17 13:48 173阅读 0赞

[https://blog.csdn.net/y601500359/article/details/80943990][https_blog.csdn.net_y601500359_article_details_80943990]

[https://www.jianshu.com/p/7c6861f0d7fd][https_www.jianshu.com_p_7c6861f0d7fd]

针对h264的解析网上优秀得博文、帖子一抓一大把，我就不在这班门弄斧了，仅仅提取一些自己在用的过程中比较有用的信息，对于sei自定义信息字段，虽然网上信息很多，但不容易精确搜到，就像我之前曾遇到一篇对我个人非常有用的文章，但后面一直找不到，现在再次看到，就把部分提取了出来，记录下，方便自己后面再次用到方便，也看能不能帮助到部分码友。

参考博客：https://www.jianshu.com/p/4d9120dfcd69

NAL header

起始码（暗红底色）"0x00000001"分割出来的比特流即是NAL unit，起始码紧跟的第一个字节(墨绿底色)是NAL header。上图“NAL header”一共出现了四个数值：

"0x06"，此时NRI为"00B"，NAL unit type为SEI类型。  
“0x67”，此时NRI为“11B”，NAL unit type为SPS类型。  
“0x68”，此时NRI为“11B”，NAL unit type为PPS类型。  
“0x65”，此时NRI为“11B”，NAL unit type为IDR图像。  
SEI payload type

"0x06"后一个字节为“0x05”（淡黄底色）是SEI payload type，即表征SEI payload分析遵循user\_data\_unregistered()语法。

在国标中。sei payload type为5，为自定义消息：如图

SEI payload size

“0x05”后一个字节为“0x2F”（淡蓝底色）是SEI payload size，此时整个payload是47个字节。

SEI payload uuid

"0x2F"随后的16个字节即为uuid，此时uuid为：

dc45e9bde6d948b7962cd820d923eeef  
SEI payload content

由于payload size是47个字节，除去16字节的uuid，剩下31个字节的content。由于content是字符串，所以有结束符"0x00"，有效的30个字符内容是

Zencoder Video Encoding System

rbsp trailing bits  
47个payload字节后的"0x80"（灰底色）即是rbsp trailing bits，在user\_data\_unregistered()里面都是按字节写入的，所以此时的NAL unit结尾写入的字节一定是0x80。

下面开始解析一段含SEI信息的H264数据，数据中包含，坐标信息，人员信息，先把代码贴出来，再一一说明代码中的各个部分：

注：已经去除起始码00 00 00 01了

可参考：https://blog.csdn.net/ab7936573/article/details/74135909

unsigned char\* data\_buf = NULL;  
if ((data\[0\] & 0x1F) == 6)//判断是否是SEI  
\{  
int nCount = 0;  
  
unsigned char buf\[1602\] = \{ 0 \};  
int nType = 0;  
unsigned char \* sei = (unsigned char \*)(data + 1);  
nCount = size;  
//获取SEI信息：payload size、payload type、uuid  
int nsize = get\_sei\_buffer(sei, ((unsigned char\*)data + size - sei), buf, &nCount, &nType);  
if (5 == nType)//判断为5，自定义消息user\_data\_unregistered()  
\{  
int nSd\_Type = buf\[0\];  
  
if (1 == nSd\_Type)  
\{  
unsigned int nSd\_Num = buf\[1\];  
m\_nNumSize = nSd\_Num;  
  
//max 100  
if (m\_nNumSize > 100)  
\{  
m\_nNumSize = 100;  
\}  
  
if (nSd\_Num > 0)  
\{  
for (int i = 0; i < m\_nNumSize; i++)  
\{  
BYTE buffer\[8\];  
//解析人脸框坐标  
buffer\[0\] = buf\[i \* 16 + 2\];  
buffer\[1\] = buf\[i \* 16 + 3\];  
unsigned short number = (buffer\[0\] << 8) + buffer\[1\];  
m\_pFaceInfo\[i\].face\_x = number;  
  
buffer\[2\] = buf\[i \* 16 + 4\];  
buffer\[3\] = buf\[i \* 16 + 5\];  
number = (buffer\[2\] << 8) + buffer\[3\];  
m\_pFaceInfo\[i\].face\_y = number;  
  
buffer\[4\] = buf\[i \* 16 + 6\];  
buffer\[5\] = buf\[i \* 16 + 7\];  
number = (buffer\[4\] << 8) + buffer\[5\];  
m\_pFaceInfo\[i\].face\_w = number;  
  
buffer\[6\] = buf\[i \* 16 + 8\];  
buffer\[7\] = buf\[i \* 16 + 9\];  
number = (buffer\[6\] << 8) + buffer\[7\];  
m\_pFaceInfo\[i\].face\_h = number;  
  
//解析人员信息  
//buffer\[8\] = \*buf++;  
m\_pFaceInfo\[i\].usrSex = buf\[i \* 16 + 10\];  
m\_pFaceInfo\[i\].userAge = buf\[i \* 16 + 11\];  
m\_pFaceInfo\[i\].userHairstyle = buf\[i \* 16 + 12\];  
m\_pFaceInfo\[i\].userHat = buf\[i \* 16 + 13\];  
m\_pFaceInfo\[i\].userBrow = buf\[i \* 16 + 16\];  
m\_pFaceInfo\[i\].userGlasses = buf\[i \* 16 + 14\];  
m\_pFaceInfo\[i\].userMask = buf\[i \* 16 + 17\];  
m\_pFaceInfo\[i\].userRace = buf\[i \* 16 + 18\];  
\}  
\}  
\}  
\}  
  
return;  
\}  
  
get\_sei\_buffer如下：

int get\_sei\_buffer(unsigned char \* data, uint32\_t size, unsigned char \* buffer, int \*count, int \*nType)  
\{  
unsigned char \* sei = data;  
int sei\_type = 0;  
unsigned sei\_size = 0;  
//payload type  
do \{  
sei\_type += \*sei;  
\*nType = sei\_type;  
\} while (\*sei++ == 255);  
//数据长度  
do \{  
sei\_size += \*sei;  
\} while (\*sei++ == 255);  
  
//检查UUID  
static unsigned char uuid\[\] = \{ 0x73, 0x74, 0x64, 0x74, 0x73, 0x74, 0x64, 0x74, 0x73, 0x74, 0x64, 0x74, 0x73, 0x74, 0x64, 0x74 \};  
  
if (sei\_size >= UUID\_SIZE && sei\_size <= (data + size - sei) &&  
sei\_type == 5 /\*&& memcmp(sei, uuid, UUID\_SIZE) == 0\*/)  
\{  
sei += UUID\_SIZE;  
sei\_size -= UUID\_SIZE;  
  
if (buffer != NULL && count != NULL)  
\{  
if (\*count > (int)sei\_size)  
\{  
memcpy(buffer, sei, sei\_size);  
\}  
\}  
  
\*count = sei\_size;  
  
return sei\_size;  
\}  
return -1;  
\}  
//获取SEI信息：payload size、payload type、uuid  
int nsize = get\_sei\_buffer(sei, ((unsigned char\*)data + size - sei), buf, &nCount, &nType);  
if (5 == nType)//判断为5，自定义消息user\_data\_unregistered()  
\{  
int nSd\_Type = buf\[0\];  
  
if (1 == nSd\_Type)  
\{  
unsigned int nSd\_Num = buf\[1\];  
m\_nNumSize = nSd\_Num;  
  
//max 100  
if (m\_nNumSize > 100)  
\{  
m\_nNumSize = 100;  
\}  
  
if (nSd\_Num > 0)  
\{  
for (int i = 0; i < m\_nNumSize; i++)  
\{  
BYTE buffer\[8\];  
//解析人脸框坐标  
buffer\[0\] = buf\[i \* 16 + 2\];  
buffer\[1\] = buf\[i \* 16 + 3\];  
unsigned short number = (buffer\[0\] << 8) + buffer\[1\];  
m\_pFaceInfo\[i\].face\_x = number;  
  
buffer\[2\] = buf\[i \* 16 + 4\];  
buffer\[3\] = buf\[i \* 16 + 5\];  
number = (buffer\[2\] << 8) + buffer\[3\];  
m\_pFaceInfo\[i\].face\_y = number;  
  
buffer\[4\] = buf\[i \* 16 + 6\];  
buffer\[5\] = buf\[i \* 16 + 7\];  
number = (buffer\[4\] << 8) + buffer\[5\];  
m\_pFaceInfo\[i\].face\_w = number;  
  
buffer\[6\] = buf\[i \* 16 + 8\];  
buffer\[7\] = buf\[i \* 16 + 9\];  
number = (buffer\[6\] << 8) + buffer\[7\];  
m\_pFaceInfo\[i\].face\_h = number;  
  
//解析人员信息  
//buffer\[8\] = \*buf++;  
m\_pFaceInfo\[i\].usrSex = buf\[i \* 16 + 10\];  
m\_pFaceInfo\[i\].userAge = buf\[i \* 16 + 11\];  
m\_pFaceInfo\[i\].userHairstyle = buf\[i \* 16 + 12\];  
m\_pFaceInfo\[i\].userHat = buf\[i \* 16 + 13\];  
m\_pFaceInfo\[i\].userBrow = buf\[i \* 16 + 16\];  
m\_pFaceInfo\[i\].userGlasses = buf\[i \* 16 + 14\];  
m\_pFaceInfo\[i\].userMask = buf\[i \* 16 + 17\];  
m\_pFaceInfo\[i\].userRace = buf\[i \* 16 + 18\];  
\}  
\}  
\}  
\}  
  
return;  
\}

————————————————  
版权声明：本文为CSDN博主「SunkingYang」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。  
原文链接：https://blog.csdn.net/y601500359/article/details/80943990

[https_blog.csdn.net_y601500359_article_details_80943990]: https://blog.csdn.net/y601500359/article/details/80943990
[https_www.jianshu.com_p_7c6861f0d7fd]: https://www.jianshu.com/p/7c6861f0d7fd