a bug（rtp rtpStream ）

[wanglong001]

hi， 我找到一个bug， SequenceNumber 是uint16，不断增加的， 最大值是 65535， 到65535后会溢出， 又从0开始.

func (r *RtpStream) AddPacket(rtp *RtpPacket) {
    if  r.CurSeq == 65535 {
        r.CurSeq = 0
    }
    if rtp.SequenceNumber <= r.CurSeq {
        return
    }
    r.EndTime = rtp.ReceivedAt
    r.CurSeq = rtp.SequenceNumber
    r.TotalExpectedPackets = uint(r.CurSeq - r.FirstSeq)
    r.LostPackets = r.TotalExpectedPackets - uint(len(r.RtpPackets))
    r.RtpPackets = append(r.RtpPackets, rtp)
}