【H.264】H.264详解（二）—— H264视频码流解析示例源码 ...

声明：此篇示例源码非原创，原作者雷霄骅。雷霄骅，中国传媒大学通信与信息系统专业博士生，在此向雷霄骅雷神致敬。
代码原文地址：视音频数据处理入门：H.264视频码流解析
一、媒介

示例源码是一个H.264码流解析程序。该程序可以从H.264码流中分析得到它的根本单元NALU，分离出NALU，然后再分析NALU的各个字段。
关于NALU的相关内容可参考文章【H.264】H.264详解（一）—— 一文看懂H.264协议
二、示例源码

【1】目录结构

1. project/
2. ├── Makefile
3. ├── h264parser.c
4. ├── sintel.h264

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【2】Makefile源码

1. app:h264parser.c
2.         gcc -o app h264parser.c
3. clean:
4.         rm -f app

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【3】h264parser.c源码

1. #include <stdio.h>
2. #include <stdlib.h>
3. #include <string.h>
5. typedef enum {
6.         NALU_TYPE_SLICE    = 1,
7.         NALU_TYPE_DPA      = 2,
8.         NALU_TYPE_DPB      = 3,
9.         NALU_TYPE_DPC      = 4,
10.         NALU_TYPE_IDR      = 5,
11.         NALU_TYPE_SEI      = 6,
12.         NALU_TYPE_SPS      = 7,
13.         NALU_TYPE_PPS      = 8,
14.         NALU_TYPE_AUD      = 9,
15.         NALU_TYPE_EOSEQ    = 10,
16.         NALU_TYPE_EOSTREAM = 11,
17.         NALU_TYPE_FILL     = 12,
18. } NaluType;
20. typedef enum {
21.         NALU_PRIORITY_DISPOSABLE = 0,
22.         NALU_PRIRITY_LOW         = 1,
23.         NALU_PRIORITY_HIGH       = 2,
24.         NALU_PRIORITY_HIGHEST    = 3
25. } NaluPriority;
27. typedef struct{
28.         int startcodeprefix_len;      //! 4 for parameter sets and first slice in picture, 3 for everything else (suggested)
29.         unsigned len;                 //! Length of the NAL unit (Excluding the start code, which does not belong to the NALU)
30.         unsigned max_size;            //! Nal Unit Buffer size
31.         int forbidden_bit;            //! should be always FALSE
32.         int nal_reference_idc;        //! NALU_PRIORITY_xxxx
33.         int nal_unit_type;            //! NALU_TYPE_xxxx   
34.         char *buf;                    //! contains the first byte followed by the EBSP
35. } NALU_t;
37. FILE *h264bitstream = NULL;                //!< the bit stream file
39. int info2=0, info3=0;
41. static int FindStartCode2 (unsigned char *Buf){
42.         if(Buf[0]!=0 || Buf[1]!=0 || Buf[2] !=1) return 0; //0x000001?
43.         else return 1;
44. }
46. static int FindStartCode3 (unsigned char *Buf){
47.         if(Buf[0]!=0 || Buf[1]!=0 || Buf[2] !=0 || Buf[3] !=1) return 0;//0x00000001?
48.         else return 1;
49. }
52. int GetAnnexbNALU (NALU_t *nalu){
53.         int pos = 0;
54.         int StartCodeFound, rewind;
55.         unsigned char *Buf;
57.         if ((Buf = (unsigned char*)calloc (nalu->max_size , sizeof(char))) == NULL)
58.                 printf ("GetAnnexbNALU: Could not allocate Buf memory\n");
60.         nalu->startcodeprefix_len=3;
62.         if (3 != fread (Buf, 1, 3, h264bitstream)){
63.                 free(Buf);
64.                 return 0;
65.         }
66.         info2 = FindStartCode2 (Buf);
67.         if(info2 != 1) {
68.                 if(1 != fread(Buf+3, 1, 1, h264bitstream)){
69.                         free(Buf);
70.                         return 0;
71.                 }
72.                 info3 = FindStartCode3 (Buf);
73.                 if (info3 != 1){
74.                         free(Buf);
75.                         return -1;
76.                 }
77.                 else {
78.                         pos = 4;
79.                         nalu->startcodeprefix_len = 4;
80.                 }
81.         }
82.         else{
83.                 nalu->startcodeprefix_len = 3;
84.                 pos = 3;
85.         }
86.         StartCodeFound = 0;
87.         info2 = 0;
88.         info3 = 0;
90.         while (!StartCodeFound){
91.                 if (feof (h264bitstream)){
92.                         nalu->len = (pos-1)-nalu->startcodeprefix_len;
93.                         memcpy (nalu->buf, &Buf[nalu->startcodeprefix_len], nalu->len);     
94.                         nalu->forbidden_bit = nalu->buf[0] & 0x80; //1 bit
95.                         nalu->nal_reference_idc = nalu->buf[0] & 0x60; // 2 bit
96.                         nalu->nal_unit_type = (nalu->buf[0]) & 0x1f;// 5 bit
97.                         free(Buf);
98.                         return pos-1;
99.                 }
100.                 Buf[pos++] = fgetc (h264bitstream);
101.                 info3 = FindStartCode3(&Buf[pos-4]);
102.                 if(info3 != 1)
103.                         info2 = FindStartCode2(&Buf[pos-3]);
104.                 StartCodeFound = (info2 == 1 || info3 == 1);
105.         }
107.         // Here, we have found another start code (and read length of startcode bytes more than we should
108.         // have.  Hence, go back in the file
109.         rewind = (info3 == 1)? -4 : -3;
111.         if (0 != fseek (h264bitstream, rewind, SEEK_CUR)){
112.                 free(Buf);
113.                 printf("GetAnnexbNALU: Cannot fseek in the bit stream file");
114.         }
116.         // Here the Start code, the complete NALU, and the next start code is in the Buf.  
117.         // The size of Buf is pos, pos+rewind are the number of bytes excluding the next
118.         // start code, and (pos+rewind)-startcodeprefix_len is the size of the NALU excluding the start code
120.         nalu->len = (pos+rewind)-nalu->startcodeprefix_len;
121.         memcpy (nalu->buf, &Buf[nalu->startcodeprefix_len], nalu->len);//
122.         nalu->forbidden_bit = nalu->buf[0] & 0x80; //1 bit
123.         nalu->nal_reference_idc = nalu->buf[0] & 0x60; // 2 bit
124.         nalu->nal_unit_type = (nalu->buf[0]) & 0x1f;// 5 bit
125.         free(Buf);
127.         return (pos+rewind);
128. }
130. /**
131. * Analysis H.264 Bitstream
132. * @param url    Location of input H.264 bitstream file.
133. */
134. int simplest_h264_parser(char *url){
135.         NALU_t *n = NULL;
136.         int buffersize=100000;
138.         //FILE *myout=fopen("output_log.txt","wb+");
139.         FILE *myout=stdout;
141.         h264bitstream=fopen(url, "rb+");
142.         if (h264bitstream==NULL){
143.                 printf("Open file error\n");
144.                 return 0;
145.         }
147.         n = (NALU_t*)calloc (1, sizeof(NALU_t));
148.         if (n == NULL){
149.                 printf("Alloc NALU Error\n");
150.                 return 0;
151.         }
153.         n->max_size=buffersize;
154.         n->buf = (char*)calloc (buffersize, sizeof(char));
155.         if (n->buf == NULL){
156.                 free (n);
157.                 printf ("AllocNALU: n->buf");
158.                 return 0;
159.         }
161.         int data_offset=0;
162.         int nal_num=0;
163.         printf("-----+-------- NALU Table ------+---------+\n");
164.         printf(" NUM |   POS   |   IDC  |  TYPE |   LEN   |\n");
165.         printf("-----+---------+--------+-------+---------+\n");
167.         while(!feof(h264bitstream)){
168.                 int data_lenth;
169.                 data_lenth=GetAnnexbNALU(n);
171.                 char type_str[20]={0};
172.                 switch(n->nal_unit_type){
173.                         case NALU_TYPE_SLICE:sprintf(type_str,"SLICE");break;
174.                         case NALU_TYPE_DPA:sprintf(type_str,"DPA");break;
175.                         case NALU_TYPE_DPB:sprintf(type_str,"DPB");break;
176.                         case NALU_TYPE_DPC:sprintf(type_str,"DPC");break;
177.                         case NALU_TYPE_IDR:sprintf(type_str,"IDR");break;
178.                         case NALU_TYPE_SEI:sprintf(type_str,"SEI");break;
179.                         case NALU_TYPE_SPS:sprintf(type_str,"SPS");break;
180.                         case NALU_TYPE_PPS:sprintf(type_str,"PPS");break;
181.                         case NALU_TYPE_AUD:sprintf(type_str,"AUD");break;
182.                         case NALU_TYPE_EOSEQ:sprintf(type_str,"EOSEQ");break;
183.                         case NALU_TYPE_EOSTREAM:sprintf(type_str,"EOSTREAM");break;
184.                         case NALU_TYPE_FILL:sprintf(type_str,"FILL");break;
185.                 }
186.                 char idc_str[20]={0};
187.                 switch(n->nal_reference_idc>>5){
188.                         case NALU_PRIORITY_DISPOSABLE:sprintf(idc_str,"DISPOS");break;
189.                         case NALU_PRIRITY_LOW:sprintf(idc_str,"LOW");break;
190.                         case NALU_PRIORITY_HIGH:sprintf(idc_str,"HIGH");break;
191.                         case NALU_PRIORITY_HIGHEST:sprintf(idc_str,"HIGHEST");break;
192.                 }
194.                 fprintf(myout,"%5d| %8d| %7s| %6s| %8d|\n",nal_num,data_offset,idc_str,type_str,n->len);
196.                 data_offset=data_offset+data_lenth;
198.                 nal_num++;
199.         }
201.         //Free
202.         if (n){
203.                 if (n->buf){
204.                         free(n->buf);
205.                         n->buf=NULL;
206.                 }
207.                 free (n);
208.         }
209.         return 0;
210. }
212. int main(int argc, char* argv[]){
213.         simplest_h264_parser("sintel.h264");
215.         return 0;
216. }

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【4】编译运行

【5】源码下载地址

H.264详解（二）- H264视频码流解析示例源码

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