rtp传输音视频(纯c代码)

参考链接: 1. PES,TS,PS,RTP等流的打包格式解析之RTP流 https://blog.csdn.net/appledurian/article/details/73135343
　　　　  2. RTP协议全解析（H264码流和PS流）https://blog.csdn.net/chen495810242/article/details/39207305

（重要）以下代码并未实测，除ts的发送外，其余都是伪代码(并且未搜集资料查询思路是否正确), 这边只为自己记录，参考请谨慎, 自己记录下而已。

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include <getopt.h>
 #include <errno.h>
 #include <unistd.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>

 static union { char c[]; unsigned long mylong; } endian_test = {{ 'l', '?', '?', 'b' } };

 #define ENDIANNESS ((char)endian_test.mylong)

 #define PRINTF_DEBUG
 #define TAB44 "    "

 #define MAX_ARGS_FILEFORMAT 10
 #define MAX_ARGS_FILEPATH 128
 #define MAX_RTPURL_IP 128
 #define MAX_ARGS_RTPURL 256
 #define MTU 1400

 #define DEFAULT_FILE_PATH "./videos/mux/ts_test.ts"
 #define DEFAULT_FILE_FORMAT "ts"
 #define DEFAULT_RTP_URL "rtp://127.0.0.1:8888"

 #define DEFAULT_ARGS {0, DEFAULT_FILE_PATH, DEFAULT_FILE_FORMAT, DEFAULT_RTP_URL}

 /* define4ts */
 #define MAX_TS_PACKET_COUNT 7
 #define TS_PACKET_LEN 188

 /* define4ps */
 #define SCODE_PS_END 0x000001B9
 #define SCODE_PS_HEADER 0x000001BA
 #define SCODE_PS_SYSTEM_HEADER 0x000001BB
 #define SCODE_PS_SYSTEM_MAP_HEADER 0x000001BC

 /* define4mpeg2 */
 typedef enum e_mpeg2_sc_type
 {
     E_SC_MPEG2_SEQ_HEADER = 0x000001B3,
     E_SC_MPEG2_SEQ_PIC_EXTEN_HEADER = 0x000001B5,
     E_SC_MPEG2_SEQ_END = 0x000001B7,
     E_SC_MPEG2_GROUP_HEADER = 0x000001B8,
     E_SC_MPEG2_PICTURE_HEADER = 0x00000100
 } E_MPEG2_SC_TYPE;

 typedef enum e_rtp_playload_type
 {
     E_RTP_PLAYLOAD_TS = ,
     E_RTP_PLAYLOAD_PS = ,
     E_RTP_PLAYLOAD_MPEG4 = ,
     E_RTP_PLAYLOAD_H264 = ,
 } E_RTP_PLAYLOAD_TYPE;

 typedef struct t_args
 {
     unsigned short isLoop;

     unsigned char filePath[MAX_ARGS_FILEPATH+];
     unsigned char fileFormat[MAX_ARGS_FILEFORMAT+];
     unsigned char rtpUrl[MAX_ARGS_RTPURL+];
 } T_ARGS;

 /******************************************************
 个人理解
 1. 位域内单字节的内存排布是定义的先后, 先定义的在内存的低地址;
 2. 位域内单字节, 字节由高到低, 先定义的为高字节;
 3. 因此对于小端(低地址放低字节).
 ******************************************************/
 typedef struct t_rtp_header
 {
     #if 1 /* 小端, BIG_ENDIAN系统宏, 暂不知道怎么用 */
     /* bytes 0 */
     unsigned char csrc_len:;
     unsigned char extension:;
     unsigned char padding:;
     unsigned char version:;
     /* bytes 1*/
     unsigned char playload:;
     unsigned char marker:;
     #else
     /* bytes 0 */
     unsigned char version:;
     unsigned char padding:;
     unsigned char extension:;
     unsigned char csrc_len:;
     /* bytes 1*/
     unsigned char marker:;
     unsigned char playload:;
     #endif

     /* byte 2, 3 */
     unsigned short seq_no;
     /* bytess 4-7 */
     unsigned int timestamp;
     /* bytes 8-11 */
     unsigned int ssrc;
 } T_RTP_HEADER;

 /* gloabl data */
 FILE *fp = NULL;

 struct sockaddr_in servAddr;

 T_ARGS defaultArgs = DEFAULT_ARGS;

 static void Usage(void)
 {
     fprintf(stderr, "usage: rtpserver [options]\n\n"
                     "Options:\n"
                     "-l | --stream_loop     Read and send strame for loop\n"
                     "-i | --filepath        File need to send\n"
                     "-f | --fileformat      Container of file(support ts, ps, h264, mpeg2, flv)\n"
                     "-s | --rtpurl          Rtp url include ip and port\n"
                     "-h | --help            Print this message\n");
 }

 /******************************************************************************
 1. const char shortOpt[] = "li:f:s:h";
    单个字符表示选项;
    单个字符后接一个冒号, 表示后面必须跟一个参数. 参数紧跟选项后或者加一个空格;
    单个字符后接两个冒号, 表示可有也可没有, 参数紧跟选项后, 不能加空格.
 2. 参数的值赋给了optarg;
 3. c = getopt_long(argc, argv, shortOpt, longOpt, NULL);
    返回值为参数字符, 若全部解析完成则返回-1.
 ******************************************************************************/
 static void ParseArgs(int argc, char *argv[], T_ARGS *args)
 {
     int c = ;

     const char shortOpt[] = "li:f:s:h";
     const struct option longOpt[] = {
         {"stream_loop",        no_argument,         NULL, 'l'},
         {"filepath",        required_argument,     NULL, 'i'},
         {"fileformat",         required_argument,     NULL, 'f'},
         {"rtpurl",           required_argument,     NULL, 's'},
         {"help",               no_argument,         NULL, 'h'},
         {, , , }
     };

     for (;;)
     {
         c = getopt_long(argc, argv, shortOpt, longOpt, NULL);

         if (- == c)
         {
             break;
         }

         switch (c)
         {
             case 'l':
                 args->isLoop = ;

                 break;

             case 'i':
                 memcpy(args->filePath, optarg, strlen(optarg));

                 args->filePath[strlen(optarg)] = '\0';

                 break;

             case 'f':
                 if (( != strcmp(optarg, "ts"))
                     && ( != strcmp(optarg, "ps")
                     && ( != strcmp(optarg, "h264")
                     && ( != strcmp(optarg, "mpeg2")
                     && ( != strcmp(optarg, "flv"))
                 {
                     Usage();

                     exit();
                 }

                 memcpy(args->fileFormat, optarg, strlen(optarg));

                 args->fileFormat[strlen(optarg)] = '\0';

                 break;

             case 's':
                 memcpy(args->rtpUrl, optarg, strlen(optarg));

                 args->rtpUrl[strlen(optarg)] = '\0';

                 break;

             default:
                 Usage();

                 exit();
         }
     }
 }

 static void Parse_RtpUrl(unsigned char* const rtpUrl, unsigned char *urlIp, unsigned short *urlPort)
 {
     unsigned short port = ;

     unsigned char *url = NULL;
     unsigned char *portStart = NULL;

     url = rtpUrl;

     url += strlen("rtp://");

     portStart = strstr(url, ":");

     port = atoi(portStart+);

     *urlPort = port;

     memcpy(urlIp, url, portStart-url);
 }

 static unsigned long GetTickCount()
 {
     struct timespec ts;

     clock_gettime(CLOCK_MONOTONIC, &ts);

     return (ts.tv_sec *  + ts.tv_nsec / );
 }

 static void Rtp_Header_Costruct(T_RTP_HEADER *rtpHeader, E_RTP_PLAYLOAD_TYPE playloadType)
 {
     static unsigned short seqNo = ;

     rtpHeader->version = ;
     rtpHeader->padding = ;
     rtpHeader->extension = ;
     rtpHeader->csrc_len = ;
     rtpHeader->marker = ;
     rtpHeader->playload = playloadType;
     rtpHeader->seq_no = seqNo++;
     rtpHeader->timestamp = htonl(GetTickCount()*/);
     rtpHeader->ssrc = htonl();
 }

 static void Rtp_DealTs(int socketFd)
 {
     int readLen = ;
     int bufCount = ;
     int packetCount = ;

     unsigned char rtpBuf[MTU] = {};

     memset(rtpBuf, 0x0, MTU);

     Rtp_Header_Costruct((T_RTP_HEADER*)rtpBuf, E_RTP_PLAYLOAD_TS);

     bufCount = sizeof(T_RTP_HEADER);

     while ()
     {
         if (feof(fp))
         {
             if (defaultArgs.isLoop)
             {
                 rewind(fp);

                 packetCount = ;

                 memset(rtpBuf, 0x0, MTU);

                 Rtp_Header_Costruct((T_RTP_HEADER*)rtpBuf, E_RTP_PLAYLOAD_TS);

                 bufCount = sizeof(T_RTP_HEADER);
             }
             else
             {
                 break;
             }
         }

         readLen = fread(rtpBuf+bufCount, , TS_PACKET_LEN, fp);

         packetCount++;
         bufCount += readLen;

         if (packetCount>=MAX_TS_PACKET_COUNT)
         {
             sendto(socketFd, rtpBuf, bufCount, , (const struct sockaddr*)&servAddr, sizeof(servAddr));

             packetCount = ;

             memset(rtpBuf, 0x0, MTU);

             Rtp_Header_Costruct((T_RTP_HEADER*)rtpBuf, E_RTP_PLAYLOAD_TS);

             bufCount = sizeof(T_RTP_HEADER);

             usleep(); // 应根据帧率发送或者可实现rtcp来动态控制发送速度
         }
     }
 }

 static void Rtp_DealPs(int socketFd)
 {
     int readLen = ;

     unsigned int startCode = ;

     while ()
     {
         if ( != fread(&startCode, , , fp))
         {
             break;
         }

         switch (startCode)
         {
             case SCODE_PS_END:
                 break;

             case SCODE_PS_HEADER:
                 /* get and send, like psparse.c */

                 break;

             case SCODE_PS_SYSTEM_HEADER:
                 /* get and send, like psparse.c  */

                 break;

             case SCODE_PS_SYSTEM_MAP_HEADER:
                 /* get and send, like psparse.c  */

                 break;

             default:
                 /*
                 1. get and send, like psparse.c;
                 2. here data mybe>MTU, 分包, 每次发MTU, 直到全部完成;
                 3. rtp头上的marker标识了一帧的开始/结束, 分包的时候刚开始写0, 最后一包填1;
                 4. 未证实: 分包时rtp头的timestamp应该是不变的.
                 */

                 break;
         }
     }
 }

 /**************************************************************************************************************************
 1. 组合封包模式
    在NALU单元很小的时候, 可以将多个NALU封装到一个RTP包里面进行传输, 分别有4种组合方式: STAP-A, STAP-B, MTAP16, MTAP24;
    那么这里的类型值分别是24, 25, 26以及27;
    我们主要介绍STAP-A, 其封包格式如下所示:
    [RTP Header] [Nalu头, type: 24(一个字节78)] [Nalu1 len(2 bytes)] [Nalu1 data] [Nalu2 len(2 bytes)] [Nalu2 data] ...
 2. 分片封包模式
    当一个NALU长度超过了MTU, 就需要采用分片的方式进行RTP封包, 将一个NALU分到多个RTP包中进行传输;
    存在两种分片类型FU-A和FU-B, 类型值分别是28和29.
    RTP+FU-A分片封包的组合方式如下:
    [RTP Header][FU indicator][FU header][payload]: 其中RTP Header占12字节, FU indicator和FU header各占1个字节;

    [FU indicator]有以下格式:
       +---------------+  
       |0|1|2|3|4|5|6|7|
       +-+-+-+-+-+-+-+-+
       |F|NRI|  Type   |
       +---------------+
       type=28表示FU-A分包

    [FU header]的格式如下：
       +---------------+  
       |0|1|2|3|4|5|6|7|
       +-+-+-+-+-+-+-+-+  
       |S|E|R|  Type   |
       +---------------+
       S: 设置成1表示此FU-A分片包为NAL单元的起始包, 其他情况设置为0;
       E：设置成1表示此FU-A分片为NAL单元的结束包, 其他情况设置为0;
       R：保留位，必须为0;
       Type: 为被分包的Nalu的type.

     简单说就是加了一个字节描述分包的开始和结束.
 *******************************************************************************************************************************/
 static void Rtp_DealH264(int socketFd)
 {
     while (!feof(fp))
     {
         /*
         1. get nalu data;
         2. sps, pps等较小的, 可采用组合封包;
         3. 帧数据大于MTU, 需分包. 如FU-A, 将帧拆分, 加上FU-A的格式, 再加上FTP的头发送出去;
         4. 以上都可参照h264parse.c
         */
     }
 }

 static void Rtp_DealMpeg2(int socketFd)
 {
     while (!feof(fp))
     {
         /*
         1. get data by startcode(seq, gop, pic...);
         2. data_len<MTU, send;
         3. data_len>MTU, 分包, 每次最大MTU;
         4. 以上都可参照mpeg2parse.c
         */
     }
 }

 static void Rtp_DealFlv(int socketFd)
 {
      while (!feof(fp))
     {
         /*
         1. get data by tag(script, video, audio...);
         2. data_len<MTU, send;
         3. data_len>MTU, 分包, 每次最大MTU;
         4. 以上都可参照flvparse.c
         */
     }
 }

 /*
 1. rtp client, send data to servAddr;
 2. server can play used rtp://ip:port
 */
 int main(int argc, char *argv[])
 {
     int socketFd = ;

     unsigned short serverPort = ;

     unsigned char serverIp[MAX_RTPURL_IP] = {};

     ParseArgs(argc, argv, &defaultArgs);

     memset(serverIp, 0x0, MAX_RTPURL_IP);

     Parse_RtpUrl(defaultArgs.rtpUrl, serverIp, &serverPort);

     socketFd = socket(AF_INET, SOCK_DGRAM, );
     if (socketFd < )
     {
         printf("%s\n", strerror(errno));

         exit();
     }

     memset(&servAddr, , sizeof(servAddr));

     servAddr.sin_family = AF_INET;
     servAddr.sin_port = htons(serverPort);
     servAddr.sin_addr.s_addr = inet_addr(serverIp);

     fp = fopen(defaultArgs.filePath, "r+");
     if (!fp)
     {
         printf("%s\n", strerror(errno));

         exit();
     }

     if ( == strcmp(defaultArgs.fileFormat, "ts"))
     {

         Rtp_DealTs(socketFd);

         fclose(fp);
     }
     else if ( == strcmp(defaultArgs.fileFormat "ps"))
     {
         Rtp_DealPs(socketFd);

         fclose(fp);
     }
     else if ( == strcmp(defaultArgs.fileFormat "h264"))
     {
         Rtp_DealH264(socketFd);

         fclose(fp);
     }
     else if ( == strcmp(defaultArgs.fileFormat "mpeg2"))
     {
         Rtp_DealMpeg2(socketFd);

         fclose(fp);
     }
     else if ( == strcmp(defaultArgs.fileFormat "flv"))
     {
         Rtp_DealFlv(socketFd);

         fclose(fp);
     }

     return ;
 }

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