/// <summary>    /// UDP数据包分割器    /// </summary>    public static class UdpPacketSplitter    {      /// <summary>      /// 分割UDP数据包      /// </summary>      /// <param name="sequence">UDP数据包所持有的序号</param>      /// <param name="datagram">被分割的UDP数据包</param>      /// <param name="chunkLength">分割块的长度</param>      /// <returns>      /// 分割后的UDP数据包列表      /// </returns>      public static ICollection<UdpPacket> Split(long sequence, byte[] datagram, int chunkLength)      {        if (datagram == null)          throw new ArgumentNullException("datagram");        List<UdpPacket> packets = new List<UdpPacket>();        int chunks = datagram.Length / chunkLength;        int remainder = datagram.Length % chunkLength;        int total = chunks;        if (remainder > 0) total++;        for (int i = 1; i <= chunks; i++)        {          byte[] chunk = new byte[chunkLength];          Buffer.BlockCopy(datagram, (i - 1) * chunkLength, chunk, 0, chunkLength);          packets.Add(new UdpPacket(sequence, total, i, chunk, chunkLength));        }        if (remainder > 0)        {          int length = datagram.Length - (chunkLength * chunks);          byte[] chunk = new byte[length];          Buffer.BlockCopy(datagram, chunkLength * chunks, chunk, 0, length);          packets.Add(new UdpPacket(sequence, total, total, chunk, length));        }        return packets;      }    }

private void WorkThread()  {    while (IsRunning)    {      waiter.WaitOne();      waiter.Reset();      while (queue.Count > 0)      {        StreamPacket packet = null;        if (queue.TryDequeue(out packet))        {          RtpPacket rtpPacket = RtpPacket.FromImage(            RtpPayloadType.JPEG,            packet.SequenceNumber,            (long)Epoch.GetDateTimeTotalMillisecondsByYesterday(packet.Timestamp),            packet.Frame);          // max UDP packet length limited to 65,535 bytes          byte[] datagram = rtpPacket.ToArray();          packet.Frame.Dispose();          // split udp packet to many packets          // to reduce the size to 65507 limit by underlying IPv4 protocol          ICollection<UdpPacket> udpPackets            = UdpPacketSplitter.Split(              packet.SequenceNumber,              datagram,              65507 - UdpPacket.HeaderSize);          foreach (var udpPacket in udpPackets)          {            byte[] udpPacketDatagram = udpPacket.ToArray();            // async sending            udpClient.BeginSend(              udpPacketDatagram, udpPacketDatagram.Length,              packet.Destination.Address,              packet.Destination.Port,              SendCompleted, udpClient);          }        }      }    }  }

private void OnDatagramReceived(object sender, UdpDatagramReceivedEventArgs<byte[]> e)      {        try        {          UdpPacket udpPacket = UdpPacket.FromArray(e.Datagram);          if (udpPacket.Total == 1)          {            RtpPacket packet = new RtpPacket(udpPacket.Payload, udpPacket.PayloadSize);            Bitmap bitmap = packet.ToBitmap();            RaiseNewFrameEvent(              bitmap, Epoch.GetDateTimeByYesterdayTotalMilliseconds(packet.Timestamp));          }          else          {            // rearrange packets to one packet            if (packetCache.ContainsKey(udpPacket.Sequence))            {              List<UdpPacket> udpPackets = null;              if (packetCache.TryGetValue(udpPacket.Sequence, out udpPackets))              {                udpPackets.Add(udpPacket);                if (udpPackets.Count == udpPacket.Total)                {                  packetCache.TryRemove(udpPacket.Sequence, out udpPackets);                  udpPackets = udpPackets.OrderBy(u => u.Order).ToList();                  int rtpPacketLength = udpPackets.Sum(u => u.PayloadSize);                  int maxPacketLength = udpPackets.Select(u => u.PayloadSize).Max();                  byte[] rtpPacket = new byte[rtpPacketLength];                  foreach (var item in udpPackets)                  {                    Buffer.BlockCopy(                      item.Payload, 0, rtpPacket,                      (item.Order - 1) * maxPacketLength, item.PayloadSize);                  }                  RtpPacket packet = new RtpPacket(rtpPacket, rtpPacket.Length);                  Bitmap bitmap = packet.ToBitmap();                  RaiseNewFrameEvent(                    bitmap,                    Epoch.GetDateTimeByYesterdayTotalMilliseconds(packet.Timestamp));                  packetCache.Clear();                }              }            }            else            {              List<UdpPacket> udpPackets = new List<UdpPacket>();              udpPackets.Add(udpPacket);              packetCache.AddOrUpdate(                udpPacket.Sequence,                udpPackets, (k, v) => { return udpPackets; });            }          }        }        catch (Exception ex)        {          RaiseVideoSourceExceptionEvent(ex.Message);        }      }