ffmpeg--tcp

TCP代码分析：

#include "avformat.h"
#include "libavutil/avassert.h"
#include "libavutil/parseutils.h"
#include "libavutil/opt.h"
#include "libavutil/time.h"

#include "internal.h"
#include "network.h"      //socket的更底层封装。
#include "os_support.h"
#include "url.h"
#if HAVE_POLL_H
#include
#endif

typedef struct TCPContext {
    const AVClass *class;
    int fd;
    int listen;
    int open_timeout;
    int rw_timeout;
    int listen_timeout;
    int recv_buffer_size;
    int send_buffer_size;
} TCPContext;

#define OFFSET(x) offsetof(TCPContext, x)
#define D AV_OPT_FLAG_DECODING_PARAM
#define E AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
    { "listen",          "Listen for incoming connections",  OFFSET(listen),         AV_OPT_TYPE_INT, { .i64 = 0 },     0,       2,       .flags = D|E },
    { "timeout",     "set timeout (in microseconds) of socket I/O operations", OFFSET(rw_timeout),     AV_OPT_TYPE_INT, { .i64 = -1 },         -1, INT_MAX, .flags = D|E },
    { "listen_timeout",  "Connection awaiting timeout (in milliseconds)",      OFFSET(listen_timeout), AV_OPT_TYPE_INT, { .i64 = -1 },         -1, INT_MAX, .flags = D|E },
    { "send_buffer_size", "Socket send buffer size (in bytes)",                OFFSET(send_buffer_size), AV_OPT_TYPE_INT, { .i64 = -1 },         -1, INT_MAX, .flags = D|E },
    { "recv_buffer_size", "Socket receive buffer size (in bytes)",             OFFSET(recv_buffer_size), AV_OPT_TYPE_INT, { .i64 = -1 },         -1, INT_MAX, .flags = D|E },
    { NULL }
};

可以设置一些参数，如：TCP监听数，超时时间，连接超时时间，收发buf。要放在最前面，如：

ffmpeg  -loglevel  verbose -recv_buffer_size  2000000  -i ....。

static const AVClass tcp_class = {
    .class_name = "tcp",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

/* return non zero if error */
static int tcp_open(URLContext *h, const char *uri, int flags)
{
    struct addrinfo hints = { 0 }, *ai, *cur_ai;
    int port, fd = -1;
    TCPContext *s = h->priv_data;
    const char *p;
    char buf[256];
    int ret;
    char hostname[1024],proto[1024],path[1024];
    char portstr[10];
    s->open_timeout = 5000000;

    av_url_split(proto, sizeof(proto), NULL, 0, hostname, sizeof(hostname),
        &port, path, sizeof(path), uri);
    if (strcmp(proto, "tcp"))
        return AVERROR(EINVAL);
    if (port <= 0 || port >= 65536) {
        av_log(h, AV_LOG_ERROR, "Port missing in uri\n");
        return AVERROR(EINVAL);
    }
    p = strchr(uri, '?');
    if (p) {
        if (av_find_info_tag(buf, sizeof(buf), "listen", p)) {
            char *endptr = NULL;
            s->listen = strtol(buf, &endptr, 10);
            /* assume if no digits were found it is a request to enable it */
            if (buf == endptr)
                s->listen = 1;
        }
        if (av_find_info_tag(buf, sizeof(buf), "timeout", p)) {
            s->rw_timeout = strtol(buf, NULL, 10);
        }
        if (av_find_info_tag(buf, sizeof(buf), "listen_timeout", p)) {
            s->listen_timeout = strtol(buf, NULL, 10);
        }
    }
    if (s->rw_timeout >= 0) {
        s->open_timeout =
        h->rw_timeout   = s->rw_timeout;
    }
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    snprintf(portstr, sizeof(portstr), "%d", port);
    if (s->listen)
        hints.ai_flags |= AI_PASSIVE;
    if (!hostname[0])
        ret = getaddrinfo(NULL, portstr, &hints, &ai);
    else
        ret = getaddrinfo(hostname, portstr, &hints, &ai);
    if (ret) {
        av_log(h, AV_LOG_ERROR,
               "Failed to resolve hostname %s: %s\n",
               hostname, gai_strerror(ret));
        return AVERROR(EIO);
    }

    cur_ai = ai;

 restart:
    fd = ff_socket(cur_ai->ai_family,
                   cur_ai->ai_socktype,
                   cur_ai->ai_protocol);       //创建SOCKET
    if (fd < 0) {
        ret = ff_neterrno();
        goto fail;
    }

    if (s->listen == 2) {
        // multi-client
        if ((ret = ff_listen(fd, cur_ai->ai_addr, cur_ai->ai_addrlen)) < 0)
            goto fail1;
    } else if (s->listen == 1) {
        // single client
        if ((ret = ff_listen_bind(fd, cur_ai->ai_addr, cur_ai->ai_addrlen,
                                  s->listen_timeout, h)) < 0)
            goto fail1;
        // Socket descriptor already closed here. Safe to overwrite to client one.
        fd = ret;
    } else {
        if ((ret = ff_listen_connect(fd, cur_ai->ai_addr, cur_ai->ai_addrlen,      //SOCKET的connect
                                     s->open_timeout / 1000, h, !!cur_ai->ai_next)) < 0) {

            if (ret == AVERROR_EXIT)
                goto fail1;
            else
                goto fail;
        }
    }

    h->is_streamed = 1;
    s->fd = fd;
    /* Set the socket's send or receive buffer sizes, if specified.
       If unspecified or setting fails, system default is used. */
    if (s->recv_buffer_size > 0) {
        setsockopt (fd, SOL_SOCKET, SO_RCVBUF, &s->recv_buffer_size, sizeof (s->recv_buffer_size));   //设置收BUF大小
    }
    if (s->send_buffer_size > 0) {
        setsockopt (fd, SOL_SOCKET, SO_SNDBUF, &s->send_buffer_size, sizeof (s->send_buffer_size));   //设置发BUF大小
    }

    freeaddrinfo(ai);
    return 0;

 fail:
    if (cur_ai->ai_next) {
        /* Retry with the next sockaddr */
        cur_ai = cur_ai->ai_next;
        if (fd >= 0)
            closesocket(fd);
        ret = 0;
        goto restart;
    }
 fail1:
    if (fd >= 0)
        closesocket(fd);
    freeaddrinfo(ai);
    return ret;
}

static int tcp_accept(URLContext *s, URLContext **c)
{
    TCPContext *sc = s->priv_data;
    TCPContext *cc;
    int ret;
    av_assert0(sc->listen);
    if ((ret = ffurl_alloc(c, s->filename, s->flags, &s->interrupt_callback)) < 0)
        return ret;
    cc = (*c)->priv_data;
    ret = ff_accept(sc->fd, sc->listen_timeout, s);   //SOCKET的accept
    if (ret < 0)
        return ff_neterrno();
    cc->fd = ret;
    return 0;
}

static int tcp_read(URLContext *h, uint8_t *buf, int size)
{
    TCPContext *s = h->priv_data;
    int ret;

    if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
        ret = ff_network_wait_fd_timeout(s->fd, 0, h->rw_timeout, &h->interrupt_callback);
        if (ret)
            return ret;
    }
    ret = recv(s->fd, buf, size, 0);     //接收
    return ret < 0 ? ff_neterrno() : ret;
}

static int tcp_write(URLContext *h, const uint8_t *buf, int size)
{
    TCPContext *s = h->priv_data;
    int ret;

    if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
        ret = ff_network_wait_fd_timeout(s->fd, 1, h->rw_timeout, &h->interrupt_callback);
        if (ret)
            return ret;
    }
    ret = send(s->fd, buf, size, MSG_NOSIGNAL);   //发送
    return ret < 0 ? ff_neterrno() : ret;
}

static int tcp_shutdown(URLContext *h, int flags)
{
    TCPContext *s = h->priv_data;
    int how;

    if (flags & AVIO_FLAG_WRITE && flags & AVIO_FLAG_READ) {
        how = SHUT_RDWR;
    } else if (flags & AVIO_FLAG_WRITE) {
        how = SHUT_WR;
    } else {
        how = SHUT_RD;
    }

    return shutdown(s->fd, how);
}

static int tcp_close(URLContext *h)
{
    TCPContext *s = h->priv_data;
    closesocket(s->fd);    //关闭
    return 0;
}

static int tcp_get_file_handle(URLContext *h)
{
    TCPContext *s = h->priv_data;
    return s->fd;
}

URLProtocol ff_tcp_protocol = {
    .name                = "tcp",
    .url_open            = tcp_open,
    .url_accept          = tcp_accept,
    .url_read            = tcp_read,
    .url_write           = tcp_write,
    .url_close           = tcp_close,
    .url_get_file_handle = tcp_get_file_handle,
    .url_shutdown        = tcp_shutdown,
    .priv_data_size      = sizeof(TCPContext),
    .flags               = URL_PROTOCOL_FLAG_NETWORK,
    .priv_data_class     = &tcp_class,
};