从零开始写一个RTSP服务器（八）一个多播的RTSP服务器

末蓝、 2021-11-02 09:10 816阅读 0赞

**从零开始写一个RTSP服务器系列**

[★我的开源项目-RtspServer][-RtspServer]

[从零开始写一个RTSP服务器（一）RTSP协议讲解][RTSP_RTSP]

[从零开始写一个RTSP服务器（二）RTSP协议的实现][RTSP_RTSP 1]

[从零开始写一个RTSP服务器（三）RTP传输H.264][RTSP_RTP_H.264]

[从零开始写一个RTSP服务器（四）一个传输H.264的RTSP服务器][RTSP_H.264_RTSP]

[从零开始写一个RTSP服务器（五）RTP传输AAC][RTSP_RTP_AAC]

[从零开始写一个RTSP服务器（六）一个传输AAC的RTSP服务器][RTSP_AAC_RTSP]

[从零开始写一个RTSP服务器（七）多播传输RTP包][RTSP_RTP]

[从零开始写一个RTSP服务器（八）一个多播的RTSP服务器][RTSP_RTSP 2]

[从零开始写一个RTSP服务器（九）一个RTP OVER RTSP/TCP的RTSP服务器][RTSP_RTP OVER RTSP_TCP_RTSP]

# 从零开始写一个RTSP服务器（八）一个多播的RTSP服务器 #

### 文章目录 ###

*  从零开始写一个RTSP服务器（八）一个多播的RTSP服务器
 *   *  一、多播的RTSP交互过程
     *  二、多播的RTSP服务器实现过程
     *   *  2.1 创建套接字
         *  2.2 创建线程向多播地址推送RTP包
         *  2.2 接收客户端连接
         *  2.3 解析命令
         *  2.4 处理请求
         *  源码
         *   *  multicast\_rtsp\_server.c
             *  rtp.h
             *  rtp.c
     *  三、测试

**本文目的**：实现一个多播传输H.264的RTSP服务器

## 一、多播的RTSP交互过程 ##

我们在前面文章[从零开始写一个RTSP服务器（二）RTSP协议的实现][RTSP_RTSP 1]中实现的RTSP交互过程是RTSP单播的情况，多播的实现过程与单播还是有所区别的，多播并不需要为每一个RTP和RTCP建立新的UDP套接字，只需要持续向一个多播地址推送RTP包就行，下面来看一个RTSP多播交互的示例

**OPTIONS**

*  C–>S
    
        OPTIONS rtsp://127.0.0.1:8554/live RTSP/1.0\r\n
        CSeq: 2\r\n
        \r\n
 *  S–>C
    
        RTSP/1.0 200 OK\r\n
        CSeq: 2\r\n
        Public: OPTIONS, DESCRIBE, SETUP, TEARDOWN, PLAY\r\n
        \r\n

**DESCRIBE**

*  C–>S
    
        DESCRIBE rtsp://127.0.0.1:8554/live RTSP/1.0\r\n
        CSeq: 3\r\n
        Accept: application/sdp\r\n
        \r\n
 *  S—>C
    
        RTSP/1.0 200 OK\r\n
        CSeq: 3\r\n
        Content-length: 225\r\n
        Content-type: application/sdp\r\n
        \r\n
        v=0
        o=- 91565615172 1 IN IP4 127.0.0.1
        t=0 0
        a=control:*
        a=type:broadcast
        a=rtcp-unicast: reflection
        m=video 39016 RTP/AVP 96
        c=IN IP4 232.123.86.248/255
        a=rtpmap:96 H264/90000
        a=framerate:25
        a=control:track0
    
    这个sdp描述文件里指明了多播地址和多播端口
    
     *  这一行表明RTCP反馈采用单播
        
            a=rtcp-unicast: reflection
        
        在多播的情况下，这表明服务端RTP发送到多播组，RTCP发送到多播组，RTCP接收采用单播
     *  这一行表明的多播目的端口为39016
        
            m=video 39016 RTP/AVP 96
     *  这一行表明了多播地址为`c=IN IP4 232.123.86.248/255`
        
            c=IN IP4 232.123.86.248/255

多播和单播的sdp文件区别主要是多播需要指定好多播地址和多播端口

关于sdp这里就不再详细讲述了，如何有不清楚请看前面的文章

**SETUP**

*  C–>S
    
        SETUP rtsp://127.0.0.1:8554/live/track0 RTSP/1.0\r\n
        CSeq: 4\r\n
        Transport: RTP/AVP;multicast;client_port=39016-39017
        \r\n
 *  S–>C
    
        RTSP/1.0 200 OK\r\n
        CSeq: 4\r\n
        Transport: RTP/AVP;multicast;destination=232.123.86.248;source=192.168.31.115;port=39016-39017;ttl=255
        Session: 66334873
        \r\n

**PLAY**

*  C–>S
    
        PLAY rtsp://127.0.0.1:8554/live RTSP/1.0\r\n
        CSeq: 5\r\n
        Session: 66334873
        Range: npt=0.000-\r\n
        \r\n
 *  S–>C
    
        RTSP/1.0 200 OK\r\n
        CSeq: 5\r\n
        Range: npt=0.000-\r\n
        Session: 66334873; timeout=60
        \r\n

## 二、多播的RTSP服务器实现过程 ##

### 2.1 创建套接字 ###

/*
     * 作者：_JT_
     * 博客：https://blog.csdn.net/weixin_42462202
     */
    
    main()
    {
        
        /* 创建套接字 */
    	serverSockfd = createTcpSocket();    
    
        /* 绑定地址和端口 */
    	bindSocketAddr(serverSockfd, "0.0.0.0", SERVER_PORT);
        
        /* 开始监听 */
        listen(serverSockfd, 10);
        
        ...
        
        while(1)
        {
        
            ...
        }
    }

### 2.2 创建线程向多播地址推送RTP包 ###

在进入while循环接收客户端前，我们创建一个线程不断地向多播地址发送RTP包

main()
    {
        
        ...
        pthread_create(&threadId, NULL, sendRtpPacket, NULL);
        
        while(1)
        {
        
            ...
        }
    }

下面看一看发送函数

/*
     * 作者：_JT_
     * 博客：https://blog.csdn.net/weixin_42462202
     */
    
    sendRtpPacket()
    {
        
        ...
        while(1)
        {
        
            ...
                
            /* 获取一帧数据 */
           	getFrameFromH264File(fd, frame, 500000); 
            
            /* 向多播地址发送RTP包 */
            rtpSendH264Frame(sockfd, MULTICAST_IP, MULTICAST_PORT,
                                rtpPacket, frame+startCode, frameSize);
            
            ...
        }
    }

### 2.2 接收客户端连接 ###

进入while循环后，开始接收客户端，然后处理客户端请求

main()
    {
        
        ...
            
        while(1)
        {
        
            /* 接收客户端 */
            acceptClient(serverSockfd, clientIp, &clientPort);
            
            /* 处理客户端 */
            doClient(clientSockfd, clientIp, clientPort);
        }
    }

下面仔细看一看如何处理客户端请求

### 2.3 解析命令 ###

先解析请求方法，然后解析序列号，再根据不同地请求做不同的处理，然后再放回结果给客户端

/*
     * 作者：_JT_
     * 博客：https://blog.csdn.net/weixin_42462202
     */
    
    doClient()
    {
        
        ...
        while(1)
        {
        
    		/* 接收请求 */
        	recv(clientSockfd, rBuf, BUF_MAX_SIZE, 0);
        	...
            /* 解析请求方法 */
            sscanf(line, "%s %s %s\r\n", method, url, version)
            ... 
            /* 解析序列号 */
            sscanf(line, "CSeq: %d\r\n", &cseq);
            
            /* 处理请求 */
            if(!strcmp(method, "OPTIONS"))
                handleCmd_OPTIONS(sBuf, cseq);
            else if(!strcmp(method, "DESCRIBE"))
                handleCmd_DESCRIBE(sBuf, cseq, url);
            else if(!strcmp(method, "SETUP"))
                handleCmd_SETUP(sBuf, cseq, localIp);
            else if(!strcmp(method, "PLAY"))
                handleCmd_PLAY(sBuf, cseq);
        
            /* 返回结果给客户端 */
        	send(clientSockfd, sBuf, strlen(sBuf), 0);
        }
    }

### 2.4 处理请求 ###

*  OPTIONS
    
        handleCmd_OPTIONS()
        {
              
            sprintf(result, "RTSP/1.0 200 OK\r\n"
                            "CSeq: %d\r\n"
                            "Public: OPTIONS, DESCRIBE, SETUP, PLAY\r\n"
                            "\r\n",
                            cseq);
        }
 *  DESCRIBE
    
    发送多播的sdp描述文件
    
        handleCmd_DESCRIBE()
        {
              
            /* 多播sdp */
            sprintf(sdp, "v=0\r\n"
                         "o=- 9%ld 1 IN IP4 %s\r\n"
                         "t=0 0\r\n"
                         "a=control:*\r\n"
                         "a=type:broadcast\r\n"
                         "a=rtcp-unicast: reflection\r\n"
                         "m=video %d RTP/AVP 96\r\n"
                         "c=IN IP4 %s/255\r\n"
                         "a=rtpmap:96 H264/90000\r\n"
                         "a=control:track0\r\n",
                         time(NULL),
                         localIp,
                         MULTICAST_PORT,
                         MULTICAST_IP);
                         
            sprintf(result, "RTSP/1.0 200 OK\r\nCSeq: %d\r\n"
                            "Content-Base: %s\r\n"
                            "Content-type: application/sdp\r\n"
                            "Content-length: %d\r\n\r\n"
                            "%s",
                            cseq,
                            url,
                            strlen(sdp),
                            sdp); 
        }
 *  SETUP
    
        handleCmd_SETUP()
        {
              
           sprintf(result, "RTSP/1.0 200 OK\r\n"
                            "CSeq: %d\r\n"
                            "Transport: RTP/AVP;multicast;destination=%s;"
                   			"source=%s;port=%d-	%d;ttl=255\r\n"
                            "Session: 66334873\r\n"
                            "\r\n",
                            cseq,
                            MULTICAST_IP,
                            localIp,
                            MULTICAST_PORT,
                            MULTICAST_PORT+1);
        }
 *  PLAY
    
        handleCmd_PLAY()
        {
              
            sprintf(result, "RTSP/1.0 200 OK\r\n"
                            "CSeq: %d\r\n"
                            "Range: npt=0.000-\r\n"
                            "Session: 66334873; timeout=60\r\n\r\n",
                            cseq);
        }
    
    在play回复完成之后，客户端就会去多播地址拉取媒体流，然后播放

### 源码 ###

源码有三个文件：`multicast_rtsp_server`、`rtp.h`、`rtp.c`

#### multicast\_rtsp\_server.c ####

/*
     * 作者：_JT_
     * 博客：https://blog.csdn.net/weixin_42462202
     */
    
    #include <stdio.h>
    #include <stdlib.h>
    #include <stdint.h>
    #include <string.h>
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <time.h>
    #include <sys/types.h>
    #include <sys/stat.h>
    #include <fcntl.h>
    #include <assert.h>
    #include <pthread.h>
    
    #include "rtp.h"
    
    #define H264_FILE_NAME      "test.h264"
    #define MULTICAST_IP        "239.255.255.11"
    #define SERVER_PORT         8554
    #define MULTICAST_PORT      9832
    #define BUF_MAX_SIZE        (1024*1024)
    
    static int createTcpSocket()
    {
        
        int sockfd;
        int on = 1;
    
        sockfd = socket(AF_INET, SOCK_STREAM, 0);
        if(sockfd < 0)
            return -1;
    
        setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (const char*)&on, sizeof(on));
    
        return sockfd;
    }
    
    static int createUdpSocket()
    {
        
        int sockfd;
        int on = 1;
    
        sockfd = socket(AF_INET, SOCK_DGRAM, 0);
        if(sockfd < 0)
            return -1;
    
        setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (const char*)&on, sizeof(on));
    
        return sockfd;
    }
    
    static int bindSocketAddr(int sockfd, const char* ip, int port)
    {
        
        struct sockaddr_in addr;
    
        addr.sin_family = AF_INET;
        addr.sin_port = htons(port);
        addr.sin_addr.s_addr = inet_addr(ip);
    
        if(bind(sockfd, (struct sockaddr *)&addr, sizeof(struct sockaddr)) < 0)
            return -1;
    
        return 0;
    }
    
    static int acceptClient(int sockfd, char* ip, int* port)
    {
        
        int clientfd;
        socklen_t len = 0;
        struct sockaddr_in addr;
    
        memset(&addr, 0, sizeof(addr));
        len = sizeof(addr);
    
        clientfd = accept(sockfd, (struct sockaddr *)&addr, &len);
        if(clientfd < 0)
            return -1;
        
        strcpy(ip, inet_ntoa(addr.sin_addr));
        *port = ntohs(addr.sin_port);
    
        return clientfd;
    }
    
    static inline int startCode3(char* buf)
    {
        
        if(buf[0] == 0 && buf[1] == 0 && buf[2] == 1)
            return 1;
        else
            return 0;
    }
    
    static inline int startCode4(char* buf)
    {
        
        if(buf[0] == 0 && buf[1] == 0 && buf[2] == 0 && buf[3] == 1)
            return 1;
        else
            return 0;
    }
    
    static char* findNextStartCode(char* buf, int len)
    {
        
        int i;
    
        if(len < 3)
            return NULL;
    
        for(i = 0; i < len-3; ++i)
        {
        
            if(startCode3(buf) || startCode4(buf))
                return buf;
            
            ++buf;
        }
    
        if(startCode3(buf))
            return buf;
    
        return NULL;
    }
    
    static int getFrameFromH264File(int fd, char* frame, int size)
    {
        
        int rSize, frameSize;
        char* nextStartCode;
    
        if(fd < 0)
            return fd;
    
        rSize = read(fd, frame, size);
        if(!startCode3(frame) && !startCode4(frame))
            return -1;
        
        nextStartCode = findNextStartCode(frame+3, rSize-3);
        if(!nextStartCode)
        {
        
            lseek(fd, 0, SEEK_SET);
            frameSize = rSize;
        }
        else
        {
        
            frameSize = (nextStartCode-frame);
            lseek(fd, frameSize-rSize, SEEK_CUR);
        }
    
        return frameSize;
    }
    
    static int rtpSendH264Frame(int socket, const char* ip, int16_t port,
                                struct RtpPacket* rtpPacket, uint8_t* frame, uint32_t frameSize)
    {
        
        uint8_t naluType; // nalu第一个字节
        int sendBytes = 0;
        int ret;
    
        naluType = frame[0];
    
        if (frameSize <= RTP_MAX_PKT_SIZE) // nalu长度小于最大包场：单一NALU单元模式
        {
        
            /*
             *   0 1 2 3 4 5 6 7 8 9
             *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             *  |F|NRI|  Type   | a single NAL unit ... |
             *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             */
            memcpy(rtpPacket->payload, frame, frameSize);
            ret = rtpSendPacket(socket, ip, port, rtpPacket, frameSize);
            if(ret < 0)
                return -1;
    
            rtpPacket->rtpHeader.seq++;
            sendBytes += ret;
            if ((naluType & 0x1F) == 7 || (naluType & 0x1F) == 8) // 如果是SPS、PPS就不需要加时间戳
                goto out;
        }
        else // nalu长度小于最大包场：分片模式
        {
        
            /*
             *  0                   1                   2
             *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
             * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             * | FU indicator  |   FU header   |   FU payload   ...  |
             * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             */
    
            /*
             *     FU Indicator
             *    0 1 2 3 4 5 6 7
             *   +-+-+-+-+-+-+-+-+
             *   |F|NRI|  Type   |
             *   +---------------+
             */
    
            /*
             *      FU Header
             *    0 1 2 3 4 5 6 7
             *   +-+-+-+-+-+-+-+-+
             *   |S|E|R|  Type   |
             *   +---------------+
             */
    
            int pktNum = frameSize / RTP_MAX_PKT_SIZE;       // 有几个完整的包
            int remainPktSize = frameSize % RTP_MAX_PKT_SIZE; // 剩余不完整包的大小
            int i, pos = 1;
    
            /* 发送完整的包 */
            for (i = 0; i < pktNum; i++)
            {
        
                rtpPacket->payload[0] = (naluType & 0x60) | 28;
                rtpPacket->payload[1] = naluType & 0x1F;
                
                if (i == 0) //第一包数据
                    rtpPacket->payload[1] |= 0x80; // start
                else if (remainPktSize == 0 && i == pktNum - 1) //最后一包数据
                    rtpPacket->payload[1] |= 0x40; // end
    
                memcpy(rtpPacket->payload+2, frame+pos, RTP_MAX_PKT_SIZE);
                ret = rtpSendPacket(socket, ip, port, rtpPacket, RTP_MAX_PKT_SIZE+2);
                if(ret < 0)
                    return -1;
    
                rtpPacket->rtpHeader.seq++;
                sendBytes += ret;
                pos += RTP_MAX_PKT_SIZE;
            }
    
            /* 发送剩余的数据 */
            if (remainPktSize > 0)
            {
        
                rtpPacket->payload[0] = (naluType & 0x60) | 28;
                rtpPacket->payload[1] = naluType & 0x1F;
                rtpPacket->payload[1] |= 0x40; //end
    
                memcpy(rtpPacket->payload+2, frame+pos, remainPktSize+2);
                ret = rtpSendPacket(socket, ip, port, rtpPacket, remainPktSize+2);
                if(ret < 0)
                    return -1;
    
                rtpPacket->rtpHeader.seq++;
                sendBytes += ret;
            }
        }
    
    out:
    
        return sendBytes;
    }
    
    static char* getLineFromBuf(char* buf, char* line)
    {
        
        while(*buf != '\n')
        {
        
            *line = *buf;
            line++;
            buf++;
        }
    
        *line = '\n';
        ++line;
        *line = '\0';
    
        ++buf;
        return buf; 
    }
    
    static int handleCmd_OPTIONS(char* result, int cseq)
    {
        
        sprintf(result, "RTSP/1.0 200 OK\r\n"
                        "CSeq: %d\r\n"
                        "Public: OPTIONS, DESCRIBE, SETUP, PLAY\r\n"
                        "\r\n",
                        cseq);
                    
        return 0;
    }
    
    static int handleCmd_DESCRIBE(char* result, int cseq, char* url)
    {
        
        char sdp[500];
        char localIp[100];
    
        sscanf(url, "rtsp://%[^:]:", localIp);
    
        sprintf(sdp, "v=0\r\n"
                     "o=- 9%ld 1 IN IP4 %s\r\n"
                     "t=0 0\r\n"
                     "a=control:*\r\n"
                     "a=type:broadcast\r\n"
                     "a=rtcp-unicast: reflection\r\n"
                     "m=video %d RTP/AVP 96\r\n"
                     "c=IN IP4 %s/255\r\n"
                     "a=rtpmap:96 H264/90000\r\n"
                     "a=control:track0\r\n",
                     time(NULL),
                     localIp,
                     MULTICAST_PORT,
                     MULTICAST_IP);
        
        sprintf(result, "RTSP/1.0 200 OK\r\nCSeq: %d\r\n"
                        "Content-Base: %s\r\n"
                        "Content-type: application/sdp\r\n"
                        "Content-length: %d\r\n\r\n"
                        "%s",
                        cseq,
                        url,
                        strlen(sdp),
                        sdp);
        
        return 0;
    }
    
    static int handleCmd_SETUP(char* result, int cseq, char* localIp)
    {
        
       sprintf(result, "RTSP/1.0 200 OK\r\n"
                        "CSeq: %d\r\n"
                        "Transport: RTP/AVP;multicast;destination=%s;source=%s;port=%d-%d;ttl=255\r\n"
                        "Session: 66334873\r\n"
                        "\r\n",
                        cseq,
                        MULTICAST_IP,
                        localIp,
                        MULTICAST_PORT,
                        MULTICAST_PORT+1);
        
        return 0;
    }
    
    static int handleCmd_PLAY(char* result, int cseq)
    {
        
        sprintf(result, "RTSP/1.0 200 OK\r\n"
                        "CSeq: %d\r\n"
                        "Range: npt=0.000-\r\n"
                        "Session: 66334873; timeout=60\r\n\r\n",
                        cseq);
        
        return 0;
    }
    
    static void doClient(int clientSockfd, const char* clientIP, int clientPort)
    {
        
        char method[40];
        char url[100];
        char localIp[40];
        char version[40];
        int cseq;
        char *bufPtr;
        char* rBuf = malloc(BUF_MAX_SIZE);
        char* sBuf = malloc(BUF_MAX_SIZE);
        char line[400];
    
        while(1)
        {
        
            int recvLen;
    
            recvLen = recv(clientSockfd, rBuf, BUF_MAX_SIZE, 0);
            if(recvLen <= 0)
                goto out;
    
            rBuf[recvLen] = '\0';
            printf("---------------C->S--------------\n");
            printf("%s", rBuf);
    
            /* 解析方法 */
            bufPtr = getLineFromBuf(rBuf, line);
            if(sscanf(line, "%s %s %s\r\n", method, url, version) != 3)
            {
        
                printf("parse err\n");
                goto out;
            }
    
            /* 解析序列号 */
            bufPtr = getLineFromBuf(bufPtr, line);
            if(sscanf(line, "CSeq: %d\r\n", &cseq) != 1)
            {
        
                printf("parse err\n");
                goto out;
            }
    
            if(!strcmp(method, "OPTIONS"))
            {
        
                if(handleCmd_OPTIONS(sBuf, cseq))
                {
        
                    printf("failed to handle options\n");
                    goto out;
                }
            }
            else if(!strcmp(method, "DESCRIBE"))
            {
        
                if(handleCmd_DESCRIBE(sBuf, cseq, url))
                {
        
                    printf("failed to handle describe\n");
                    goto out;
                }
            }
            else if(!strcmp(method, "SETUP"))
            {
        
                sscanf(url, "rtsp://%[^:]:", localIp);
                if(handleCmd_SETUP(sBuf, cseq, localIp))
                {
        
                    printf("failed to handle setup\n");
                    goto out;
                }
            }
            else if(!strcmp(method, "PLAY"))
            {
        
                if(handleCmd_PLAY(sBuf, cseq))
                {
        
                    printf("failed to handle play\n");
                    goto out;
                }
            }
            else
            {
        
                goto out;
            }
    
            printf("---------------S->C--------------\n");
            printf("%s", sBuf);
            send(clientSockfd, sBuf, strlen(sBuf), 0);
        }
    out:
        printf("finish\n");
        close(clientSockfd);
        free(rBuf);
        free(sBuf);
    }
    
    void* sendRtpPacket(void* arg)
    {
        
        int fd;
        int frameSize, startCode;
        char* frame = malloc(500000);
        struct RtpPacket* rtpPacket = (struct RtpPacket*)malloc(500000);
        int sockfd = createUdpSocket();
        assert(sockfd > 0);
    
        fd = open(H264_FILE_NAME, O_RDONLY);
        assert(fd > 0);
    
        rtpHeaderInit(rtpPacket, 0, 0, 0, RTP_VESION, RTP_PAYLOAD_TYPE_H264, 0,
                                0, 0, 0x88923423);
    
        while(1)
        {
        
            frameSize = getFrameFromH264File(fd, frame, 500000);
    
            if(startCode3(frame))
                startCode = 3;
            else
                startCode = 4;
            
            frameSize -= startCode;
            rtpSendH264Frame(sockfd, MULTICAST_IP, MULTICAST_PORT,
                                rtpPacket, frame+startCode, frameSize);
            rtpPacket->rtpHeader.timestamp += 90000/25;
    
            usleep(1000*1000/25);
        }
    
        free(frame);
        free(rtpPacket);
        close(fd);
    
        return NULL;
    }
    
    int main(int argc, char* argv[])
    {
        
        int serverSockfd;
        int ret;
        pthread_t threadId;
    
        serverSockfd = createTcpSocket();
        if(serverSockfd < 0)
        {
        
            printf("failed to create tcp socket\n");
            return -1;
        }
    
        ret = bindSocketAddr(serverSockfd, "0.0.0.0", SERVER_PORT);
        if(ret < 0)
        {
        
            printf("failed to bind addr\n");
            return -1;
        }
    
        ret = listen(serverSockfd, 10);
        if(ret < 0)
        {
        
            printf("failed to listen\n");
            return -1;
        }
    
        printf("rtsp://127.0.0.1:%d\n", SERVER_PORT);
    
        pthread_create(&threadId, NULL, sendRtpPacket, NULL);
    
        while(1)
        {
        
            int clientSockfd;
            char clientIp[40];
            int clientPort;
    
            clientSockfd = acceptClient(serverSockfd, clientIp, &clientPort);
            if(clientSockfd < 0)
            {
        
                printf("failed to accept client\n");
                return -1;
            }
    
            printf("accept client;client ip:%s,client port:%d\n", clientIp, clientPort);
    
            doClient(clientSockfd, clientIp, clientPort);
        }
    
        return 0;
    }

#### rtp.h ####

/*
     * 作者：_JT_
     * 博客：https://blog.csdn.net/weixin_42462202
     */
    
    #ifndef _RTP_H_
    #define _RTP_H_
    #include <stdint.h>
    
    #define RTP_VESION              2
    
    #define RTP_PAYLOAD_TYPE_H264   96
    #define RTP_PAYLOAD_TYPE_AAC    97
    
    #define RTP_HEADER_SIZE         12
    #define RTP_MAX_PKT_SIZE        1400
    
    /*
     *
     *    0                   1                   2                   3
     *    7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0
     *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     *   |V=2|P|X|  CC   |M|     PT      |       sequence number         |
     *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     *   |                           timestamp                           |
     *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     *   |           synchronization source (SSRC) identifier            |
     *   +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
     *   |            contributing source (CSRC) identifiers             |
     *   :                             ....                              :
     *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     *
     */
    struct RtpHeader
    {
        
        /* byte 0 */
        uint8_t csrcLen:4;
        uint8_t extension:1;
        uint8_t padding:1;
        uint8_t version:2;
    
        /* byte 1 */
        uint8_t payloadType:7;
        uint8_t marker:1;
        
        /* bytes 2,3 */
        uint16_t seq;
        
        /* bytes 4-7 */
        uint32_t timestamp;
        
        /* bytes 8-11 */
        uint32_t ssrc;
    };
    
    struct RtpPacket
    {
        
        struct RtpHeader rtpHeader;
        uint8_t payload[0];
    };
    
    void rtpHeaderInit(struct RtpPacket* rtpPacket, uint8_t csrcLen, uint8_t extension,
                        uint8_t padding, uint8_t version, uint8_t payloadType, uint8_t marker,
                       uint16_t seq, uint32_t timestamp, uint32_t ssrc);
    int rtpSendPacket(int socket, const char* ip, int16_t port, struct RtpPacket* rtpPacket, uint32_t dataSize);
    
    #endif //_RTP_H_

#### rtp.c ####

/*
     * 作者：_JT_
     * 博客：https://blog.csdn.net/weixin_42462202
     */
    
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <arpa/inet.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    
    #include "rtp.h"
    
    void rtpHeaderInit(struct RtpPacket* rtpPacket, uint8_t csrcLen, uint8_t extension,
                        uint8_t padding, uint8_t version, uint8_t payloadType, uint8_t marker,
                       uint16_t seq, uint32_t timestamp, uint32_t ssrc)
    {
        
        rtpPacket->rtpHeader.csrcLen = csrcLen;
        rtpPacket->rtpHeader.extension = extension;
        rtpPacket->rtpHeader.padding = padding;
        rtpPacket->rtpHeader.version = version;
        rtpPacket->rtpHeader.payloadType =  payloadType;
        rtpPacket->rtpHeader.marker = marker;
        rtpPacket->rtpHeader.seq = seq;
        rtpPacket->rtpHeader.timestamp = timestamp;
        rtpPacket->rtpHeader.ssrc = ssrc;
    }
    
    int rtpSendPacket(int socket, const char* ip, int16_t port, struct RtpPacket* rtpPacket, uint32_t dataSize)
    {
        
        struct sockaddr_in addr;
        int ret;
    
        addr.sin_family = AF_INET;
        addr.sin_port = htons(port);
        addr.sin_addr.s_addr = inet_addr(ip);
    
        rtpPacket->rtpHeader.seq = htons(rtpPacket->rtpHeader.seq);
        rtpPacket->rtpHeader.timestamp = htonl(rtpPacket->rtpHeader.timestamp);
        rtpPacket->rtpHeader.ssrc = htonl(rtpPacket->rtpHeader.ssrc);
    
        ret = sendto(socket, (void*)rtpPacket, dataSize+RTP_HEADER_SIZE, 0,
                        (struct sockaddr*)&addr, sizeof(addr));
    
        rtpPacket->rtpHeader.seq = ntohs(rtpPacket->rtpHeader.seq);
        rtpPacket->rtpHeader.timestamp = ntohl(rtpPacket->rtpHeader.timestamp);
        rtpPacket->rtpHeader.ssrc = ntohl(rtpPacket->rtpHeader.ssrc);
    
        return ret;
    }

## 三、测试 ##

将`multicast_rtsp_server.c`、`rtp.h`、`rtp.c`保存下来

编译运行，程序默认会打开`test.h264`的视频文件，如果你没有视频源的话，可以从[RtspServer][]的example目录下获取

# gcc multicast_rtsp_server.c rtp.c -lpthread
    # ./a.out

运行后会打印一个url

rtsp://127.0.0.1:8554

在vlc中输入url，就可以播放了

*  运行效果
    
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQ2MjIwMg_size_16_color_FFFFFF_t_70]

[-RtspServer]: https://blog.csdn.net/weixin_42462202/article/details/98956346
[RTSP_RTSP]: https://blog.csdn.net/weixin_42462202/article/details/98986535
[RTSP_RTSP 1]: https://blog.csdn.net/weixin_42462202/article/details/99068041
[RTSP_RTP_H.264]: https://blog.csdn.net/weixin_42462202/article/details/99089020
[RTSP_H.264_RTSP]: https://blog.csdn.net/weixin_42462202/article/details/99111635
[RTSP_RTP_AAC]: https://blog.csdn.net/weixin_42462202/article/details/99200935
[RTSP_AAC_RTSP]: https://blog.csdn.net/weixin_42462202/article/details/99311193
[RTSP_RTP]: https://blog.csdn.net/weixin_42462202/article/details/99329048
[RTSP_RTSP 2]: https://blog.csdn.net/weixin_42462202/article/details/99413781
[RTSP_RTP OVER RTSP_TCP_RTSP]: https://blog.csdn.net/weixin_42462202/article/details/99442338
[RtspServer]: https://github.com/ImSjt/RtspServer
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQ2MjIwMg_size_16_color_FFFFFF_t_70]: /images/20211101/225d93b216414fdba41a558c0c8f553d.png