static int rtp_read(URLContext *h, uint8_t *buf, int size)
{
    RTPContext *s = h->priv_data;
    struct sockaddr_storage from;
    socklen_t from_len;
    int len, fd_max, n;
    fd_set rfds;
    struct timeval tv;
#if 0
    for(;;) {
        from_len = sizeof(from);
        len = recvfrom (s->rtp_fd, buf, size, 0,
                        (struct sockaddr *)&from, &from_len);
        if (len < 0) {
            if (ff_neterrno() == FF_NETERROR(EAGAIN) ||
                ff_neterrno() == FF_NETERROR(EINTR))
                continue;
            return AVERROR(EIO);
        }
        break;
    }
#else
    for(;;) {
        if (url_interrupt_cb())
            return AVERROR(EINTR);
        /* build fdset to listen to RTP and RTCP packets */
        FD_ZERO(&rfds);
        fd_max = s->rtp_fd;
        FD_SET(s->rtp_fd, &rfds);
        if (s->rtcp_fd > fd_max)
            fd_max = s->rtcp_fd;
        FD_SET(s->rtcp_fd, &rfds);
        tv.tv_sec = 0;
        tv.tv_usec = 100 * 1000;
        n = select(fd_max + 1, &rfds, NULL, NULL, &tv);
        if (n > 0) {
            /* first try RTCP */
            if (FD_ISSET(s->rtcp_fd, &rfds)) {
                from_len = sizeof(from);
                len = recvfrom (s->rtcp_fd, buf, size, 0,
                                (struct sockaddr *)&from, &from_len);
                if (len < 0) {
                    if (ff_neterrno() == FF_NETERROR(EAGAIN) ||
                        ff_neterrno() == FF_NETERROR(EINTR))
                        continue;
                    return AVERROR(EIO);
                }
                break;
            }
            /* then RTP */
            if (FD_ISSET(s->rtp_fd, &rfds)) {
                from_len = sizeof(from);
                len = recvfrom (s->rtp_fd, buf, size, 0,
                                (struct sockaddr *)&from, &from_len);
                if (len < 0) {
                    if (ff_neterrno() == FF_NETERROR(EAGAIN) ||
                        ff_neterrno() == FF_NETERROR(EINTR))
                        continue;
                    return AVERROR(EIO);
                }
                break;
            }
        } else if (n < 0) {
            if (ff_neterrno() == FF_NETERROR(EINTR))
                continue;
            return AVERROR(EIO);
        }
    }
#endif
    return len;
}