最近使用C#编写一个摄像头的本地监控及录像程序，硬件开发商把所有的功能实现封装到DLL里了，我通过C#调用之。
具体要实现的功能如下：
1、摄像头通过DAS功能，主动向监控主机的IP发送数据。
2、监控主机监听固定端口，处理接收到的数据。
我自己的思路：
1、新建一个Dictionary存储已上线设备的信息。
2、程序初始化H264_DVR_Init(DisCallback, 0)，DisCallback为断线回调函数，设备断线后将设备信息从Dictionary剔除。
3、程序通过调用DLL中的H264_DVR_StartActiveRigister(port, ActiveRegCallBack, 0))方法开始监听端口，ActiveRegCallBack为设备上线后的回调函数，能够得到上线设备的信息。
遇到的问题：
现在程序能够正常的运行，设备发送数据也能接受并显示，但是如果有一个已连接的设备断线后，当这个设备再次连接时或新设备上线时程序就崩溃，显示VSHOST32.EXE已停止工作，即使关闭项目属性中“启用visual studio承载进程”后也会崩溃。
现将部分代码贴上，感谢大神！跪谢！
//----------------------------------------------------------------------------------------------------
//初始化SDK
public void InitSDK()
{
DisCallback = new XMSDK.DisConnectCallBackDelegate(DisConnectBackCall);
GC.KeepAlive(DisCallback);
if (XMSDK.H264_DVR_Init(DisCallback, 0))
{
Console.Write(NowTime() + "系统初始化，成功！");
系统实时信息.AppendText(DateTime.Now.ToLongDateString().ToString() + DateTime.Now.ToLongTimeString().ToString() + " ： " + "系统初始化，成功！");
File.AppendAllText(LogSavePath, NowTime() + "系统初始化，成功！", Encoding.UTF8);
}
else
{
Console.Write(NowTime() + "系统初始化，失败！");
系统实时信息.AppendText(NowTime() + "系统初始化，失败！");
File.AppendAllText(LogSavePath, NowTime() + "系统初始化，失败！", Encoding.UTF8);
}
}
//----------------------------------------------------------------------------------------------------
//断线回掉函数，输出断线信息，停止RealPlay、PC端录像
void DisConnectBackCall(int lLoginID, string pchDVRIP, int nDVRPort, IntPtr dwUser)
{
ActiveRegListStruct ActiveRegListOne;
ActiveRegList.TryGetValue(lLoginID, out ActiveRegListOne);
Message = new MessageStruct();
Message.msg = "设备：" + ActiveRegListOne.RasID + "（" + ActiveRegListOne.SerialNumber + "）" + "，断线！";
ShowMessage();
if (XMSDK.H264_DVR_StopLocalRecord(ActiveRegListOne.RealPlayID))
{
ActiveRegListOne.RecordingTime = -1;
Message = new MessageStruct();
Message.msg = "设备：" + ActiveRegListOne.RasID + "（" + ActiveRegListOne.SerialNumber + "）" + "，停止PC端录像！";
ShowMessage();
}
if (XMSDK.H264_DVR_StopRealPlay(ActiveRegListOne.RealPlayID, (uint)ActiveRegListOne.Handle))
{
ActiveRegListOne.RealPlayID = -1;
Message = new MessageStruct();
Message.msg = "设备：" + ActiveRegListOne.RasID + "（" + ActiveRegListOne.SerialNumber + "）" + "，停止实时监视！";
ShowMessage();
}
if (ActiveRegList.ContainsKey(lLoginID))
{
ActiveRegList.Remove(lLoginID);
}
AddToTreeView();
}
//----------------------------------------------------------------------------------------------------
//设备主动注册
public void StartActiveRigister()
{
int port = 9300;
ActiveRegCallBack = new XMSDK.ActiveRigisterCallBackDelegate(ActiveRigisterCallBack);
if (XMSDK.H264_DVR_StartActiveRigister(port, ActiveRegCallBack, 0))
{
PrintMessage("远程设备主动注册监听，成功！");
PrintMessage("开始监听：" + port.ToString() + "端口，等待设备连接。");
}
else
{
PrintMessage("远程设备主动注册监听开始，失败！");
}
}
//----------------------------------------------------------------------------------------------------
//主动监听回调函数
public void ActiveRigisterCallBack(int lLoginID, IntPtr pBuf, uint dwBufLen, uint dwUser)
{
H264_DVR_ACTIVEREG_INFO ActiveClientInfo;
ActiveClientInfo = (H264_DVR_ACTIVEREG_INFO)Marshal.PtrToStructure(pBuf, typeof(H264_DVR_ACTIVEREG_INFO));
if (ActiveRegList.Count < 6)
{
ActiveRegListStruct ActiveRegListOne;
ActiveRegListOne.LoginID = lLoginID;
ActiveRegListOne.RasID = ActiveClientInfo.deviceSarialID;
ActiveRegListOne.SerialNumber = ActiveClientInfo.deviceInfo.sSerialNumber;
ActiveRegListOne.VideoOutChannel = ActiveClientInfo.deviceInfo.iVideoOutChannel;
ActiveRegListOne.deviceInfo = ActiveClientInfo.deviceInfo;
ActiveRegListOne.RealPlayID = -1;
ActiveRegListOne.RecordingTime = -1;
ActiveRegListOne.isSetKeepLifeTime = XMSDK.H264_DVR_SetKeepLifeTime(lLoginID, 1, 1 * 2);
ActiveRegListOne.Handle = HandleArray[ActiveRegList.Count];
ActiveRegList.Add(lLoginID, ActiveRegListOne);
NowActiveReg = ActiveRegListOne;
//----------------------------------------------------------------------------------------------------
//更新设备列表TreeView
AddToTreeView();
//----------------------------------------------------------------------------------------------------
//开始RealPlay和PC端录像
StartRealPlayLocalRecord();
}
else
{
MessageBox.Show("当前连接数过多，本系统最多支持6个通道连接!");
}
}
class XMSDK
{
public delegate void DisConnectCallBackDelegate(int lLoginID, string pchDVRIP, int nDVRPort, IntPtr dwUser); //断线回调函数，回调出当前已经断开的设备
public delegate void ActiveRigisterCallBackDelegate(int lLoginID, IntPtr pBuf, uint dwBufLen, uint dwUser);
[DllImport("NetSdk.dll")]
public static extern bool H264_DVR_Init(DisConnectCallBackDelegate cbDisConnect,uint dwUser); //SDK初始化
[DllImport("NetSdk.dll")]
public static extern bool H264_DVR_StartActiveRigister(int nPort, ActiveRigisterCallBackDelegate cbFunc, uint dwDataUser); //远程设备主动注册监听
[DllImport("NetSdk.dll")]
public static extern bool H264_DVR_StopActiveRigister(); //远程设备主动注册监听
[DllImport("NetSdk.dll")]
public static extern int H264_DVR_RealPlay(int lLoginID, ref H264_DVR_CLIENTINFO lpClientInfo);
[DllImport("NetSdk.dll")]
public static extern bool H264_DVR_StopRealPlay(int lLoginID, uint dwUser);
[DllImport("NetSdk.dll")]
public static extern bool H264_DVR_StartLocalRecord(int lRealHandle, string szSaveFileName, int type);
[DllImport("NetSdk.dll")]
public static extern bool H264_DVR_StopLocalRecord(int lRealHandle);
[DllImport("NetSdk.dll")]
public static extern bool H264_DVR_SetKeepLifeTime(int lLoginID, int perKeeplifeTime, int detectDisconTime);
[DllImport("NetSdk.dll")]
public static extern int H264_DVR_GetLastError();
[DllImport("NetSdk.dll")]
public static extern bool H264_DVR_Cleanup();
}
public struct ActiveRegListStruct
{
public int LoginID;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
public String RasID; //RAS-ID 类似于laizhou
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
public String SerialNumber;//设备序列号 MAC地址 唯一标识符
public int VideoOutChannel; //单个设备输出通道数
public bool isSetKeepLifeTime; //设置心跳时间是否成功的返回值,1 成功,0 失败
public int RealPlayID; //执行RealPlay方法的返回值，用于LoaclRecord
public int RecordingTime;//显示已录像多长时间，-1为没有开始录像
public IntPtr Handle; //Handle
public H264_DVR_DEVICEINFO deviceInfo;
}
//----------------------------------------------------------------------------------------------------
//已连接的设备列表
public static Dictionary ActiveRegList = new Dictionary();
