(s->cur_timestamp * 90000LL * FRAME_RATE_BASE) / st->codec.frame_rate;
av_rescale((int64_t)s->cur_timestamp * st->codec.frame_rate_base, 90000, st->codec.frame_rate);
static void rtp_send_raw(AVFormatContext *s1,                         uint8_t *buf1, int size){    RTPContext *s = s1->priv_data;    AVStream *st = s1->streams[0];    int len, max_packet_size;    max_packet_size = s->max_payload_size;    while (size > 0) {        len = max_packet_size;        if (len > size)            len = size;        /* 90 KHz time stamp */        /* XXX: overflow */        s->timestamp = s->base_timestamp +             (s->cur_timestamp * 90000LL * FRAME_RATE_BASE) / st->codec.frame_rate;        rtp_send_data(s1, buf1, len);        buf1 += len;        size -= len;    }    s->cur_timestamp++;}