c++用ffmpeg创建rtsp服务器

使用FFmpeg创建RTSP服务器的步骤如下：

1. 安装FFmpeg库和开发包。
2. 编写C++代码，使用FFmpeg库创建RTSP服务器。
3. 创建RTSP服务器的主循环，接受RTSP请求并处理。
4. 实现RTSP协议中的OPTIONS、DESCRIBE、SETUP、PLAY和TEARDOWN方法。
5. 将RTSP流媒体数据编码为H.264或其他格式，并通过RTSP协议发送。

下面是一个简单的C++代码示例，用于创建基本的RTSP服务器：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <pthread.h>
#include <errno.h>
#include <time.h>

extern "C" {
#include <libavformat/avformat.h>
#include <libavutil/opt.h>
#include <libavcodec/avcodec.h>
#include <libswscale/swscale.h>
#include <libavutil/imgutils.h>
}

// RTSP请求方法
enum rtsp_method {
    RTSP_OPTIONS = 0,
    RTSP_DESCRIBE,
    RTSP_SETUP,
    RTSP_PLAY,
    RTSP_TEARDOWN,
};

// RTSP请求结构体
struct rtsp_request {
    enum rtsp_method method;
    char url[256];
    char cseq[16];
    char session[16];
};

// RTSP服务器结构体
struct rtsp_server {
    int sockfd;
    struct sockaddr_in addr;
    pthread_t thread;
    int running;
};

// 处理RTSP请求
void handle_rtsp_request(int sockfd, struct sockaddr_in *client_addr, struct rtsp_request *request);

// RTSP服务器线程
void *rtsp_server_thread(void *arg);

// 创建RTSP服务器
int create_rtsp_server(int port);

// 释放RTSP服务器资源
void free_rtsp_server(struct rtsp_server *server);

// 将YUV420P的图像数据编码为H.264
AVPacket *encode_yuv420p_to_h264(AVCodecContext *codec_ctx, AVFrame *frame);

// 获取当前时间的字符串表示，格式为：YYYY-MM-DD HH:MM:SS
char *get_current_time_string();

int main(int argc, char **argv) {
    // 初始化FFmpeg库
    av_register_all();
    avcodec_register_all();
    avformat_network_init();

    // 创建RTSP服务器
    struct rtsp_server *server = (struct rtsp_server *)malloc(sizeof(struct rtsp_server));
    server->running = 1;
    server->sockfd = create_rtsp_server(8554);

    // 启动RTSP服务器线程
    pthread_create(&server->thread, NULL, rtsp_server_thread, (void *)server);

    // 等待RTSP服务器线程退出
    pthread_join(server->thread, NULL);

    // 释放RTSP服务器资源
    free_rtsp_server(server);

    return 0;
}

void handle_rtsp_request(int sockfd, struct sockaddr_in *client_addr, struct rtsp_request *request) {
    char response[1024];
    char *session_id;
    struct timeval tv;

    // 获取当前时间
    gettimeofday(&tv, NULL);

    switch (request->method) {
        case RTSP_OPTIONS:
            // 处理RTSP OPTIONS请求
            sprintf(response, "RTSP/1.0 200 OK\r\n"
                              "CSeq: %s\r\n"
                              "Public: OPTIONS,DESCRIBE,SETUP,PLAY,TEARDOWN\r\n\r\n",
                    request->cseq);
            sendto(sockfd, response, strlen(response), 0, (struct sockaddr *)client_addr, sizeof(struct sockaddr_in));
            break;
        case RTSP_DESCRIBE:
            // 处理RTSP DESCRIBE请求
            sprintf(response, "RTSP/1.0 200 OK\r\n"
                              "CSeq: %s\r\n"
                              "Content-Type: application/sdp\r\n\r\n"
                              "v=0\r\n"
                              "o=- %ld %ld IN IP4 %s\r\n"
                              "s=RTSP Server\r\n"
                              "c=IN IP4 %s\r\n"
                              "t=0 0\r\n"
                              "a=control:*\r\n"
                              "m=video 0 RTP/AVP 96\r\n"
                              "a=rtpmap:96 H264/90000\r\n"
                              "a=fmtp:96 packetization-mode=1;profile-level-id=64000c;sprop-parameter-sets=Z00AKJWgKA9k,aM48gA==\r\n",
                    request->cseq, tv.tv_sec, tv.tv_usec, inet_ntoa(client_addr->sin_addr), inet_ntoa(client_addr->sin_addr));
            sendto(sockfd, response, strlen(response), 0, (struct sockaddr *)client_addr, sizeof(struct sockaddr_in));
            break;
        case RTSP_SETUP:
            // 处理RTSP SETUP请求
            session_id = request->session[0] == '\0' ? get_current_time_string() : request->session;
            sprintf(response, "RTSP/1.0 200 OK\r\n"
                              "CSeq: %s\r\n"
                              "Transport: RTP/AVP;unicast;client_port=%d-%d;server_port=6970-6971\r\n"
                              "Session: %s\r\n\r\n",
                    request->cseq, ntohs(client_addr->sin_port), ntohs(client_addr->sin_port) + 1, session_id);
            sendto(sockfd, response, strlen(response), 0, (struct sockaddr *)client_addr, sizeof(struct sockaddr_in));
            break;
        case RTSP_PLAY:
            // 处理RTSP PLAY请求
            sprintf(response, "RTSP/1.0 200 OK\r\n"
                              "CSeq: %s\r\n"
                              "RTP-Info: url=%s;seq=0;rtptime=0\r\n"
                              "Session: %s\r\n\r\n",
                    request->cseq, request->url, request->session);
            sendto(sockfd, response, strlen(response), 0, (struct sockaddr *)client_addr, sizeof(struct sockaddr_in));
            break;
        case RTSP_TEARDOWN:
            // 处理RTSP TEARDOWN请求
            sprintf(response, "RTSP/1.0 200 OK\r\n"
                              "CSeq: %s\r\n\r\n",
                    request->cseq);
            sendto(sockfd, response, strlen(response), 0, (struct sockaddr *)client_addr, sizeof(struct sockaddr_in));
            break;
        default:
            // 不支持的RTSP请求方法
            sprintf(response, "RTSP/1.0 405 Method Not Allowed\r\n"
                              "CSeq: %s\r\n\r\n",
                    request->cseq);
            sendto(sockfd, response, strlen(response), 0, (struct sockaddr *)client_addr, sizeof(struct sockaddr_in));
            break;
    }
}

void *rtsp_server_thread(void *arg) {
    struct rtsp_server *server = (struct rtsp_server *)arg;
    struct sockaddr_in client_addr;
    socklen_t addr_len = sizeof(struct sockaddr_in);
    char buffer[1024];
    int nbytes;
    struct rtsp_request request;

    while (server->running) {
        nbytes = recvfrom(server->sockfd, buffer, sizeof(buffer), 0, (struct sockaddr *)&client_addr, &addr_len);
        if (nbytes < 0) {
            // 接收数据失败
            continue;
        }
        buffer[nbytes] = '\0';

        // 解析RTSP请求
        if (sscanf(buffer, "%s %s RTSP/1.0\r\n"
                            "CSeq: %s\r\n"
                            "Session: %s\r\n",
                   request.method == RTSP_SETUP ? request.url : request.url + 1,
                   request.url,
                   request.cseq,
                   request.session) != 4) {
            // 解析失败
            continue;
        }

        // 处理RTSP请求
        handle_rtsp_request(server->sockfd, &client_addr, &request);
    }

    return NULL;
}

int create_rtsp_server(int port) {
    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
        perror("socket");
        exit(1);
    }

    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(struct sockaddr_in));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = INADDR_ANY;
    addr.sin_port = htons(port);

    if (bind(sockfd, (struct sockaddr *)&addr, sizeof(struct sockaddr_in)) < 0) {
        perror("bind");
        exit(1);
    }

    return sockfd;
}

void free_rtsp_server(struct rtsp_server *server) {
    close(server->sockfd);
    free(server);
}

AVPacket *encode_yuv420p_to_h264(AVCodecContext *codec_ctx, AVFrame *frame) {
    AVPacket *packet = av_packet_alloc();
    if (!packet) {
        return NULL;
    }

    int ret = avcodec_send_frame(codec_ctx, frame);
    if (ret < 0) {
        av_packet_free(&packet);
        return NULL;
    }

    ret = avcodec_receive_packet(codec_ctx, packet);
    if (ret < 0) {
        av_packet_free(&packet);
        return NULL;
    }

    return packet;
}

char *get_current_time_string() {
    static char str[20];
    time_t t = time(NULL);
    strftime(str, sizeof(str), "%Y-%m-%d %H:%M:%S", localtime(&t));
    return str;
}

该示例仅提供了基本的RTSP服务器实现，不能直接用于实际生产环境。实际使用时需要根据需求进行修改和扩展。