C#海康车牌识别实战指南带源码

前言

车牌识别技术在智能交通、停车场管理等领域有着广泛的应用。海康威视作为国内领先的安防厂商，其车牌识别相机提供了丰富的SDK接口供开发者使用。本文将详细介绍如何使用C#语言结合海康威视SDK实现车牌识别功能，并解析关键代码实现。

一、环境准备

在开始之前，需要准备以下环境：

Visual Studio（推荐2017或更高版本）
海康威视网络SDK（HCNetSDK.dll）
海康威视车牌识别相机设备
.NET Framework 4.0或更高版本

二、项目结构

本项目包含两个核心类文件：

LicenseCameraGroup.cs - 管理多个车牌识别相机的组类
LicenseCameraItem.cs - 单个车牌识别相机的实现类

三、核心代码解析

1. LicenseCameraGroup类解析

LicenseCameraGroup类负责管理多个车牌识别相机，主要功能包括初始化SDK、启动监听服务和处理识别结果。

初始化SDK

public bool Init(List<lpr_entity> dataList, List<PictureBox> licenseCameraPicList)
{try{LprList = dataList;bool m_bInitSDK = CHCNetSDK.NET_DVR_Init();if (m_bInitSDK == false){return false;}else{// 设置SDK日志路径CHCNetSDK.NET_DVR_SetLogToFile(3, "C:\\SdkLog\\", true);// 设置异常消息回调函数if (m_fExceptionCB == null){m_fExceptionCB = new CHCNetSDK.EXCEPYIONCALLBACK(cbExceptionCB);}CHCNetSDK.NET_DVR_SetExceptionCallBack_V30(0, IntPtr.Zero, m_fExceptionCB, IntPtr.Zero);// 设置报警回调函数if (m_falarmData_V31 == null){m_falarmData_V31 = new CHCNetSDK.MSGCallBack_V31(MsgCallback_V31);}CHCNetSDK.NET_DVR_SetDVRMessageCallBack_V31(m_falarmData_V31, IntPtr.Zero);}// 初始化每个车牌识别相机int a = 0;foreach (var item in dataList){LicenseCameraItem licenseCameraItem = new LicenseCameraItem();licenseCameraItem.Init(item.ip, item.port, item.serial_port, item.baud_rate, item.license_account, item.license_password, licenseCameraPicList[a], item.communication_mode);a++;}// 启动监听线程Thread thread = new Thread(StartListen);thread.IsBackground = true;thread.Start();return true;}catch (Exception ex){return false;}
}

启动监听服务

public void StartListen()
{sLocalIP = GetIpV4();ushort wLocalPort = 7200;if (m_falarmData == null){m_falarmData = new CHCNetSDK.MSGCallBack(MsgCallback);}iListenHandle = CHCNetSDK.NET_DVR_StartListen_V30(sLocalIP, wLocalPort, m_falarmData, IntPtr.Zero);if (iListenHandle < 0){iLastErr = CHCNetSDK.NET_DVR_GetLastError();strErr = "启动监听失败，错误号：" + iLastErr;return;}
}

处理车牌识别结果

private void ProcessCommAlarm_ITSPlate(ref CHCNetSDK.NET_DVR_ALARMER pAlarmer, IntPtr pAlarmInfo, uint dwBufLen, IntPtr pUser)
{CHCNetSDK.NET_ITS_PLATE_RESULT struITSPlateResult = new CHCNetSDK.NET_ITS_PLATE_RESULT();uint dwSize = (uint)Marshal.SizeOf(struITSPlateResult);struITSPlateResult = (CHCNetSDK.NET_ITS_PLATE_RESULT)Marshal.PtrToStructure(pAlarmInfo, typeof(CHCNetSDK.NET_ITS_PLATE_RESULT));// 保存抓拍图片for (int i = 0; i < struITSPlateResult.dwPicNum; i++){if (struITSPlateResult.struPicInfo[i].dwDataLen != 0){int iLen = (int)struITSPlateResult.struPicInfo[i].dwDataLen;byte[] by = new byte[iLen];Marshal.Copy(struITSPlateResult.struPicInfo[i].pBuffer, by, 0, iLen);if (isSavePic){// 保存图片到指定路径if (!System.IO.Directory.Exists(path)){System.IO.Directory.CreateDirectory(path);}string str = path + "\\[" + name + "]_Pictype_" + struITSPlateResult.struPicInfo[i].byType + "_PicNum[" + (i + 1) + "]_" + iFileNumber + ".jpg";FileStream fs = new FileStream(str, FileMode.Create);fs.Write(by, 0, iLen);fs.Close();iFileNumber++;}}}// 获取识别到的车牌号码string stringPlateLicense = System.Text.Encoding.GetEncoding("GBK").GetString(struITSPlateResult.struPlateInfo.sLicense).TrimEnd('\0');if (!CardIds.Contains(stringPlateLicense)){CardIds.Add(stringPlateLicense);}// 触发车牌识别事件isFront = strIP == LprList[0].ip;GetNumberEvent(CardIds, isFront);CardIds.Clear();
}

2. LicenseCameraItem类解析

LicenseCameraItem类负责单个车牌识别相机的管理，包括相机初始化、登录、预览和布防等功能。

相机初始化

public bool Init(string ip, string port, string account, string password)
{try{_IP = ip;_Port = port;_Account = account;_Password = password;bool m_bInitSDK = CHCNetSDK.NET_DVR_Init();if (m_bInitSDK == false){return false;}return true;}catch (Exception ex){return false;}
}

相机登录

public bool CameraLogin1(out int num, string iP, string port, string account, string password)
{try{//相机参数不能为空if (String.IsNullOrEmpty(iP) || String.IsNullOrEmpty(port) || String.IsNullOrEmpty(account) || String.IsNullOrEmpty(password)){num = 0;return false;}struLogInfo = new CHCNetSDK.NET_DVR_USER_LOGIN_INFO();//登录//设备IP地址或者域名byte[] byIP = System.Text.Encoding.Default.GetBytes(iP);struLogInfo.sDeviceAddress = new byte[129];byIP.CopyTo(struLogInfo.sDeviceAddress, 0);//设备用户名byte[] byUserName = System.Text.Encoding.Default.GetBytes(account);struLogInfo.sUserName = new byte[64];byUserName.CopyTo(struLogInfo.sUserName, 0);//设备密码byte[] byPassword = System.Text.Encoding.Default.GetBytes(password);struLogInfo.sPassword = new byte[64];byPassword.CopyTo(struLogInfo.sPassword, 0);struLogInfo.wPort = ushort.Parse(port);//设备服务端口号if (LoginCallBack == null){LoginCallBack = new CHCNetSDK.LOGINRESULTCALLBACK(cbLoginCallBack);//注册回调函数                    }struLogInfo.cbLoginResult = LoginCallBack;struLogInfo.bUseAsynLogin = false; //是否异步登录：0- 否，1- 是 DeviceInfo = new CHCNetSDK.NET_DVR_DEVICEINFO_V40();//登录设备m_lUserID = CHCNetSDK.NET_DVR_Login_V40(ref struLogInfo, ref DeviceInfo);if (m_lUserID < 0){iLastErr = CHCNetSDK.NET_DVR_GetLastError();num = 0;return false;}num = m_lUserID;return true;}catch (Exception ex){num = 0;return false;}
}

打开相机预览

private bool OpenLicenseCamera(PictureBox LicenseCameraPic, string licenseIp, string licensePort, string licenseAccount, string licensePassword)
{try{if (Init(licenseIp, licensePort, licenseAccount, licensePassword)){if (CameraLogin1(out int num, licenseIp, licensePort, licenseAccount, licensePassword)){m_lUserID = num;}else{return false;}//成功后打开摄像头CHCNetSDK.NET_DVR_PREVIEWINFO lpPreviewInfo = new CHCNetSDK.NET_DVR_PREVIEWINFO();lpPreviewInfo.hPlayWnd = LicenseCameraPic.Handle;//预览窗口lpPreviewInfo.lChannel = 1;//预te览的设备通道lpPreviewInfo.dwStreamType = 0;//码流类型：0-主码流，1-子码流，2-码流3，3-码流4，以此类推lpPreviewInfo.dwLinkMode = 0;//连接方式：0- TCP方式，1- UDP方式，2- 多播方式，3- RTP方式，4-RTP/RTSP，5-RSTP/HTTP lpPreviewInfo.bBlocked = true; //0- 非阻塞取流，1- 阻塞取流lpPreviewInfo.dwDisplayBufNum = 1; //播放库播放缓冲区最大缓冲帧数lpPreviewInfo.byProtoType = 0;lpPreviewInfo.byPreviewMode = 0;if (RealData == null){RealData = new CHCNetSDK.REALDATACALLBACK(RealDataCallBack);//预览实时流回调函数}IntPtr pUser = new IntPtr();//用户数据//打开预览m_lRealHandle = CHCNetSDK.NET_DVR_RealPlay_V40(m_lUserID, ref lpPreviewInfo, null/*RealData*/, pUser);if (m_lRealHandle < 0){iLastErr = CHCNetSDK.NET_DVR_GetLastError();return false;}//监听车牌线程Thread thread = new Thread(LicenseThread);thread.IsBackground = true;thread.Start();return true;}return false;}catch (Exception ex){return false;}
}

四、使用示例

// 创建车牌识别组
LicenseCameraGroup licenseCameraGroup = new LicenseCameraGroup();// 订阅车牌识别事件
licenseCameraGroup.GetNumberEvent += (cardIds, isFront) =>
{foreach (string cardId in cardIds){Console.WriteLine($"识别到车牌: {cardId}, 方向: {(isFront ? "前" : "后")}");}
};// 初始化车牌识别相机
List<lpr_entity> lprList = new List<lpr_entity>
{new lpr_entity { ip = "192.168.1.64", port = "8000", license_account = "admin", license_password = "12345" }
};List<PictureBox> pictureBoxes = new List<PictureBox> { pictureBox1 };
licenseCameraGroup.Init(lprList, pictureBoxes);