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[4]; 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 = 33,
    E_RTP_PLAYLOAD_PS = 96,
    E_RTP_PLAYLOAD_MPEG4 = 97,
    E_RTP_PLAYLOAD_H264 = 98,
} E_RTP_PLAYLOAD_TYPE;

typedef struct t_args 
{
    unsigned short isLoop;
    
    unsigned char filePath[MAX_ARGS_FILEPATH+1];
    unsigned char fileFormat[MAX_ARGS_FILEFORMAT+1];
    unsigned char rtpUrl[MAX_ARGS_RTPURL+1];
} 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:4;
    unsigned char extension:1;
    unsigned char padding:1;
    unsigned char version:2;
    /* bytes 1*/
    unsigned char playload:7;
    unsigned char marker:1;
    #else
    /* bytes 0 */
    unsigned char version:2;
    unsigned char padding:1;
    unsigned char extension:1;
    unsigned char csrc_len:4;
    /* bytes 1*/
    unsigned char marker:1;
    unsigned char playload:7;
    #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]

"
                    "Options:
"
                    "-l | --stream_loop     Read and send strame for loop
"
                    "-i | --filepath        File need to send
"
                    "-f | --fileformat      Container of file(support ts, ps, h264, mpeg2, flv)
"
                    "-s | --rtpurl          Rtp url include ip and port
"
                    "-h | --help            Print this message
");
}

/******************************************************************************
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 = 0;
    
    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'},
        {0, 0, 0, 0}
    };

    for (;;)
    {
        c = getopt_long(argc, argv, shortOpt, longOpt, NULL);
        
        if (-1 == c)
        {
            break;
        }
        
        switch (c)
        {
            case 'l':
                args->isLoop = 1;
                
                break;
                
            case 'i':
                memcpy(args->filePath, optarg, strlen(optarg));
                
                args->filePath[strlen(optarg)] = '';
                
                break;
                
            case 'f':
                if ((0 != strcmp(optarg, "ts"))
                    && (0 != strcmp(optarg, "ps")
                    && (0 != strcmp(optarg, "h264")
                    && (0 != strcmp(optarg, "mpeg2")
                    && (0 != strcmp(optarg, "flv"))
                {
                    Usage();
                    
                    exit(0);
                }
                
                memcpy(args->fileFormat, optarg, strlen(optarg));
                

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

            case 's':            
                memcpy(args->rtpUrl, optarg, strlen(optarg));
                
                args->rtpUrl[strlen(optarg)] = '';
                
                break;

            default:
                Usage();
                
                exit(0);
        }
    }
}

static void Parse_RtpUrl(unsigned char* const rtpUrl, unsigned char *urlIp, unsigned short *urlPort)
{
    unsigned short port = 0;
    
    unsigned char *url = NULL;
    unsigned char *portStart = NULL;
    
    url = rtpUrl;
    
    url += strlen("rtp://");
    
    portStart = strstr(url, ":");
    
    port = atoi(portStart+1);
    
    *urlPort = port;
    
    memcpy(urlIp, url, portStart-url);
}

static unsigned long GetTickCount()
{
    struct timespec ts;

    clock_gettime(CLOCK_MONOTONIC, &ts);

    return (ts.tv_sec * 1000 + ts.tv_nsec / 1000000);
}

static void Rtp_Header_Costruct(T_RTP_HEADER *rtpHeader, E_RTP_PLAYLOAD_TYPE playloadType)
{
    static unsigned short seqNo = 111;
    
    rtpHeader->version = 2;
    rtpHeader->padding = 0;
    rtpHeader->extension = 0;
    rtpHeader->csrc_len = 0;
    rtpHeader->marker = 0;
    rtpHeader->playload = playloadType;
    rtpHeader->seq_no = seqNo++;
    rtpHeader->timestamp = htonl(GetTickCount()*1000/90000);
    rtpHeader->ssrc = htonl(111);
}

static void Rtp_DealTs(int socketFd)
{
    int readLen = 0;
    int bufCount = 0;
    int packetCount = 0;
    
    unsigned char rtpBuf[MTU] = {0};

    memset(rtpBuf, 0x0, MTU);

    Rtp_Header_Costruct((T_RTP_HEADER*)rtpBuf, E_RTP_PLAYLOAD_TS);

    bufCount = sizeof(T_RTP_HEADER);
        
    while (1)
    {
        if (feof(fp))
        {
            if (defaultArgs.isLoop)
            {
                rewind(fp);
                
                packetCount = 0;

                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, 1, TS_PACKET_LEN, fp);
        
        packetCount++;
        bufCount += readLen;
        
        if (packetCount>=MAX_TS_PACKET_COUNT)
        {
            sendto(socketFd, rtpBuf, bufCount, 0, (const struct sockaddr*)&servAddr, sizeof(servAddr));
            
            packetCount = 0;
            
            memset(rtpBuf, 0x0, MTU);

            Rtp_Header_Costruct((T_RTP_HEADER*)rtpBuf, E_RTP_PLAYLOAD_TS);

            bufCount = sizeof(T_RTP_HEADER);
            
            usleep(100); // 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 = 0;
    
    unsigned int startCode = 0;
    
    while (1)
    {
        if (4 != fread(&startCode, 4, 1, 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 = 0;
    
    unsigned short serverPort = 0;

    unsigned char serverIp[MAX_RTPURL_IP] = {0};
    
    ParseArgs(argc, argv, &defaultArgs);
    
    memset(serverIp, 0x0, MAX_RTPURL_IP);
    
    Parse_RtpUrl(defaultArgs.rtpUrl, serverIp, &serverPort);

    socketFd = socket(AF_INET, SOCK_DGRAM, 0);
    if (socketFd < 0)
    {
        printf("%s
", strerror(errno));
        
        exit(0);
    }
    
    memset(&servAddr, 0, 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
", strerror(errno));

        exit(0);
    }

    if (0 == strcmp(defaultArgs.fileFormat, "ts"))
    {

        Rtp_DealTs(socketFd);
        
        fclose(fp);
    }
    else if (0 == strcmp(defaultArgs.fileFormat "ps"))
    {
        Rtp_DealPs(socketFd);
        
        fclose(fp);
    }
    else if (0 == strcmp(defaultArgs.fileFormat "h264"))
    {
        Rtp_DealH264(socketFd);

        fclose(fp);
    }
    else if (0 == strcmp(defaultArgs.fileFormat "mpeg2"))
    {
        Rtp_DealMpeg2(socketFd);

        fclose(fp);
    }
    else if (0 == strcmp(defaultArgs.fileFormat "flv"))
    {
        Rtp_DealFlv(socketFd);

        fclose(fp);
    }

    return 0;
}

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