rtp丢包重传demo

基于ffmpeg, 稍作修改，测试例子： 

ffmpeg -fflags +genpts -re -i 0Cannon.f4v \

 -an -vcodec copy -f rtp rtp://224.0.0.239:5002?localport=5000 \
 -vn -acodec copy -f rtp rtp://224.0.0.239:5004?localport=5006 \
 > live.sdp

sed -i 's/AVP/AVPF/g' live.sdp

#修改rtpdec.c，强制发送RTCP_RTPFB,重新编译后，
./ffplay -sdp_flags +rtcp_to_source ~/video/live.sdp

#receive video - audio, listen on video feedback from clients

./mc 224.0.0.239 5002 224.0.0.239 5004 127.0.0.1 5001 127.0.0.1 5007

这里的127.0.0.1 5001 是客户端丢视频包后请求重传的地址。

/*mingw: gcc -g -O0 mc.c -lws2_32*/#include <stdint.h>#ifdef _WIN32#include <winsock2.h>#include <ws2tcpip.h>#define HAVE_WINSOCK2_H 1#ifndef EPROTONOSUPPORT#define EPROTONOSUPPORT WSAEPROTONOSUPPORT#endif#ifndef ETIMEDOUT#define ETIMEDOUT       WSAETIMEDOUT#endif#ifndef ECONNREFUSED#define ECONNREFUSED    WSAECONNREFUSED#endif#ifndef EINPROGRESS#define EINPROGRESS     WSAEINPROGRESS#endif#define SHUT_RD SD_RECEIVE#define SHUT_WR SD_SEND#define SHUT_RDWR SD_BOTH#define getsockopt(a, b, c, d, e) getsockopt(a, b, c, (char*) d, e)#define setsockopt(a, b, c, d, e) setsockopt(a, b, c, (const char*) d, e)struct pollfd {    int fd;    short events;  /* events to look for */    short revents; /* events that occurred */};typedef int nfds_t;/* events & revents */#define POLLIN     0x0001  /* any readable data available */#define POLLOUT    0x0002  /* file descriptor is writeable */#define POLLRDNORM POLLIN#define POLLWRNORM POLLOUT#define POLLRDBAND 0x0008  /* priority readable data */#define POLLWRBAND 0x0010  /* priority data can be written */#define POLLPRI    0x0020  /* high priority readable data *//* revents only */#define POLLERR    0x0004  /* errors pending */#define POLLHUP    0x0080  /* disconnected */#define POLLNVAL   0x1000  /* invalid file descriptor */int ff_poll(struct pollfd *fds, nfds_t numfds, int timeout);#define poll ff_poll#else#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <poll.h>#define closesocket close#endif#include <time.h>#include <string.h>#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <fcntl.h> //F_SETFL#include <errno.h> //EAGAIN#include <stdint.h>#define MAX_GROUP 2000#define MSGBUFSIZE 2048 #define PKT_Q_S 128enum {MCAST_STATE_READ = 1,MCAST_STATE_WRITE,};typedef struct mcast{int fd;uint32_t ssrc;int state;struct sockaddr_in faddr; /*from addr*/socklen_t faddrlen;uint8_t *pkt_data[PKT_Q_S];int pkt_size[PKT_Q_S];int widx; /*current writing index*/struct mcast *ref_mcast;int ref_idx[PKT_Q_S];int ref_seq[PKT_Q_S];int ref_count;int ref_w;struct mcast *next;}mcast_t;static mcast_t s_mcast[MAX_GROUP];#ifdef _WIN32int ff_poll(struct pollfd *fds, nfds_t numfds, int timeout){    fd_set read_set;    fd_set write_set;    fd_set exception_set;    nfds_t i;    int n;    int rc;#if HAVE_WINSOCK2_H    if (numfds >= FD_SETSIZE) {        errno = EINVAL;        return -1;    }#endif /* HAVE_WINSOCK2_H */    FD_ZERO(&read_set);    FD_ZERO(&write_set);    FD_ZERO(&exception_set);    n = 0;    for (i = 0; i < numfds; i++) {        if (fds[i].fd < 0)            continue;#if !HAVE_WINSOCK2_H        if (fds[i].fd >= FD_SETSIZE) {            errno = EINVAL;            return -1;        }#endif /* !HAVE_WINSOCK2_H */        if (fds[i].events & POLLIN)            FD_SET(fds[i].fd, &read_set);        if (fds[i].events & POLLOUT)            FD_SET(fds[i].fd, &write_set);        if (fds[i].events & POLLERR)            FD_SET(fds[i].fd, &exception_set);        if (fds[i].fd >= n)            n = fds[i].fd + 1;    }    if (n == 0)        /* Hey!? Nothing to poll, in fact!!! */        return 0;    if (timeout < 0) {        rc = select(n, &read_set, &write_set, &exception_set, NULL);    } else {        struct timeval tv;        tv.tv_sec  = timeout / 1000;        tv.tv_usec = 1000 * (timeout % 1000);        rc         = select(n, &read_set, &write_set, &exception_set, &tv);    }    if (rc < 0)        return rc;    for (i = 0; i < numfds; i++) {        fds[i].revents = 0;        if (FD_ISSET(fds[i].fd, &read_set))            fds[i].revents |= POLLIN;        if (FD_ISSET(fds[i].fd, &write_set))            fds[i].revents |= POLLOUT;        if (FD_ISSET(fds[i].fd, &exception_set))            fds[i].revents |= POLLERR;    }    return rc;}#endifint ff_socket_nonblock(int socket, int enable){#if HAVE_WINSOCK2_H    u_long param = enable;    return ioctlsocket(socket, FIONBIO, ¶m);#else    if (enable)        return fcntl(socket, F_SETFL, fcntl(socket, F_GETFL) | O_NONBLOCK);    else        return fcntl(socket, F_SETFL, fcntl(socket, F_GETFL) & ~O_NONBLOCK);#endif /* HAVE_WINSOCK2_H */}#define AV_RB16(x) (((x)[0] << 8) | (x)[1])#define AV_RB32(x) (((x)[0] << 24) | ((x)[1] << 16) | ((x)[2] << 8) | (x)[3])#define FFMIN(x, y) ((x) < (y) ? (x) : (y) )#define RTP_PT_PRIVATE 96#define RTP_VERSION 2#define RTP_FLAG_KEY    0x1 ///< RTP packet contains a keyframe#define RTP_FLAG_MARKER 0x2 ///< RTP marker bit was set for this packet/* RTCP packet types http://tools.ietf.org/html/rfc4585#section-6 */enum RTCPType {    RTCP_FIR    = 192,    RTCP_NACK, // 193    RTCP_SMPTETC,// 194    RTCP_IJ,   // 195    RTCP_SR     = 200,    RTCP_RR,   // 201    RTCP_SDES, // 202    RTCP_BYE,  // 203    RTCP_APP,  // 204    RTCP_RTPFB,// 205    RTCP_PSFB, // 206    RTCP_XR,   // 207    RTCP_AVB,  // 208    RTCP_RSI,  // 209    RTCP_TOKEN,// 210};static char* mcast_dump(mcast_t *mc){static char buf[512];char *ptr = buf, *end = buf + sizeof(buf)-16;int i;ptr += sprintf(ptr, "ssrc %x seq ", mc->ssrc);for(i = 0; i < mc->ref_count && ptr < end; ++i){ptr += sprintf(ptr, "%d ", mc->ref_seq[i]);}return buf;}static int find_cached_rtp(mcast_t *mc, uint16_t first_missing, uint16_t following_mask){/*return >0 means found and fillter*/int i, j, k, cnt = 0;uint16_t seq;uint8_t *ptr;mcast_t *m = &s_mcast[0];for(; m; m = m->next){if(m->ssrc == mc->ssrc){break;}}if(!m){return -1;}for(i = 0; i < PKT_Q_S; ++i){if(!m->pkt_data[i]){continue;}seq = AV_RB16(m->pkt_data[i]+2);if(seq == first_missing){break;}}if(i >= PKT_Q_S){return -2;}cnt = 0;mc->ref_mcast = m;m->ref_seq[cnt] = seq;m->ref_idx[cnt++] = i;for(j = 1; j <= 16; ++j){if(following_mask & (1<<(j-1))){k = (i+ j)%PKT_Q_S;ptr = m->pkt_data[k];if(ptr && AV_RB16(ptr+2) == (seq+j)){m->ref_seq[cnt] = seq+j;m->ref_idx[cnt++] = k;}}}m->ref_count = cnt;m->ref_w = 0;return cnt;}static int rtcp_parse_packet(mcast_t *mc, uint8_t *buf, int len){    int payload_len;    while (len >= 4) {        payload_len = FFMIN(len, (AV_RB16(buf + 2) + 1) * 4);//printf("rtcp %u len %u\n", buf[1], payload_len);switch (buf[1]){case RTCP_SR://rtcp_send_srbreak;case RTCP_BYE:return -RTCP_BYE;break;case RTCP_RR:break;case RTCP_RTPFB:if(buf[0] == ((RTP_VERSION << 6)|1) && MCAST_STATE_READ == mc->state){uint32_t ssrc = AV_RB32(buf+8);uint16_t first_missing = AV_RB16(buf+12);uint16_t missing_mask = AV_RB16(buf+14);//printf(" missing seq %u %04x on ssrc %x\n", first_missing, missing_mask, ssrc);if(mc->ssrc && mc->ssrc != ssrc){mc->ssrc = 0;return -1;}mc->ssrc = ssrc;mc->ref_w = mc->ref_count = 0;if(find_cached_rtp(mc, first_missing, missing_mask) > 0){mcast_t *mr = mc->ref_mcast;mr->faddr = mc->faddr;mr->faddrlen = mc->faddrlen;mr->state = MCAST_STATE_WRITE;}}break;}        buf += payload_len;        len -= payload_len;    }    return -1;}static int rtp_parse_one_packet(mcast_t *mc, uint8_t *buf, int len){/* ref ff_rtp_send_data/avio_flush --> udp boud per seq.*/unsigned int ssrc;    int payload_type, seq, flags;    int ext, csrc;    uint32_t timestamp;uint8_t *ptr;if (len < 12 || (buf[0] & 0xc0) != (RTP_VERSION << 6)){fprintf(stderr, "bad rtp len %d %x\n", len, buf[0]);        return -1;}    csrc         = buf[0] & 0x0f;    ext          = buf[0] & 0x10;    payload_type = buf[1] & 0x7f;    if (buf[1] & 0x80)        flags = RTP_FLAG_MARKER;    seq       = AV_RB16(buf + 2);    timestamp = AV_RB32(buf + 4);    ssrc      = AV_RB32(buf + 8);if(mc->widx >=0){ptr = mc->pkt_data[mc->widx];if(mc->ssrc != ssrc || (ptr && seq != (AV_RB16(ptr + 2) + 1)%65536) ){mc->widx = -1; /*reset*/return 0;}mc->widx = (mc->widx + 1) % PKT_Q_S;}else{/*first time*/mc->ssrc = ssrc;mc->widx = 0; }if(mc->pkt_data[mc->widx]){free(mc->pkt_data[mc->widx]);}mc->pkt_data[mc->widx] = buf;mc->pkt_size[mc->widx] = len;mc->ssrc = ssrc;//printf("==rtp seq %u payload %x %u\n", seq, buf[0], len);return 0;}static int parse_packet(mcast_t *mc, uint8_t *buf, int len){int is_rtcp = (RTCP_FIR <= buf[1] && buf[1] <= RTCP_IJ)|| (RTCP_SR <= buf[1] && buf[1] <= RTCP_TOKEN);return is_rtcp ? rtcp_parse_packet(mc, buf, len) :rtp_parse_one_packet(mc, buf, len);}static int is_multcast_addr(char *str){if(!str){return 0;}int a = atoi(str);if(224 <= a && a <=239){return 1;}return 0;}static int mcast_open(char *ip, int port){struct sockaddr_in saddr;struct in_addr iaddr;struct ip_mreq mreq;int flag, ret;int fd = socket(AF_INET, SOCK_DGRAM, 0);if(fd < 0){perror("socket");goto end;}flag = 1;ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag));if(ret < 0){perror("Reusing ADDR failed");goto end;}memset(&saddr, 0, sizeof(saddr));saddr.sin_family = AF_INET;saddr.sin_addr.s_addr = htonl(INADDR_ANY); saddr.sin_port = htons(port);;ret = bind(fd, (struct sockaddr *)&saddr,sizeof(struct sockaddr_in));if(ret < 0){perror("err bind");goto end;}ff_socket_nonblock(fd, 1);if(is_multcast_addr(ip)){memset(&iaddr, 0, sizeof(struct in_addr));iaddr.s_addr = INADDR_ANY;setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, &iaddr, sizeof(iaddr));//IP_MULTICAST_TTLmreq.imr_multiaddr.s_addr = inet_addr(ip);mreq.imr_interface.s_addr = htonl(INADDR_ANY);ret = setsockopt(fd, IPPROTO_IP,IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));if (ret < 0){perror("set sock opt");goto end;}}return fd;end:if(fd >= 0){closesocket(fd);}return -1;}int main(int ac, char *av[]){struct sockaddr_in saddr;int nbytes, addrlen;int flag, ret, i, cnt;if(ac < 3 || !(ac&1)){return printf("usage: mc 224.0.0.239 5000 [remote_ip remote_port ... feedback_ip feedback_port]\n");}#ifdef _WIN32WSADATA wsd;WSAStartup(MAKEWORD(1, 1), &wsd);#endifcnt = 0;for(i = 1; i < ac && i < MAX_GROUP; i += 2){int fd = mcast_open(av[i], atoi(av[i+1]));if(fd < 0){printf("error of %d ip %s\n", errno, av[i]);}else{s_mcast[cnt].fd = fd;s_mcast[cnt].state = MCAST_STATE_READ;s_mcast[cnt].widx = -1;s_mcast[cnt].next = s_mcast + cnt+1;++cnt;}}if(cnt < 1){return -1;}s_mcast[cnt-1].next = NULL;while (1) {struct pollfd pe[MAX_GROUP] = {{0}};for(i = 0; i < cnt; ++i){pe[i].fd = s_mcast[i].fd;if(MCAST_STATE_WRITE == s_mcast[i].state){pe[i].events = POLLOUT;}else{pe[i].events = POLLIN;}}do{ret = poll(pe, cnt, 500);if(ret < 0 && errno != EAGAIN && errno != EINTR){printf("error of %d\n", errno);goto end;}}while(ret < 0);for(i = 0; i < cnt; ++i){mcast_t *mc = s_mcast + i;if(pe[i].revents & POLLIN){mc->faddrlen = sizeof(mc->faddr);uint8_t *msgbuf = malloc(MSGBUFSIZE);if(!msgbuf){printf("malloc for read err\n");goto end;}nbytes = recvfrom(pe[i].fd, msgbuf, MSGBUFSIZE, 0, (struct sockaddr *)&mc->faddr, &mc->faddrlen);if(nbytes < 0 && errno != EAGAIN && errno != EINTR) {printf("read error ret %d err %d\n", nbytes, errno);goto end;}if(nbytes > 0){parse_packet(mc, msgbuf, nbytes);}else{free(msgbuf);}}if(pe[i].revents & POLLOUT){if(mc->ref_w < mc->ref_count){int idx = mc->ref_idx[mc->ref_w];sendto(mc->fd, mc->pkt_data[idx], mc->pkt_size[idx], 0, (struct sockaddr *)&mc->faddr, mc->faddrlen);mc->ref_w++;if(mc->ref_w >= mc->ref_count){printf("sent %s\n", mcast_dump(mc));mc->state = MCAST_STATE_READ;}}}}}end:for(i = 0; i < cnt; ++i){if(s_mcast[i].fd > 0){closesocket(s_mcast[i].fd);}}#ifdef _WIN32    WSACleanup();#endifreturn 0;}

todo: 

考虑怎么动态指定重传地址。