C#实现海康威视智能车牌识别

一、系统架构设计

1. 核心模块划分

csharp 复制代码

// 主程序入口
public class LicenseRecognitionSystem {
    private HCNetSDK sdk = new HCNetSDK();
    private List<CameraDevice> devices = new List<CameraDevice>();
    
    // 初始化流程
    public bool Initialize() {
        if (!sdk.NET_DVR_Init()) return false;
        devices.AddRange(CameraManager.DiscoverDevices());
        return devices.All(d => d.Login());
    }
}

2. 设备通信模型

csharp 复制代码

public class CameraDevice {
    public string IP { get; set; }
    public int Port { get; set; }
    public string Username { get; set; }
    public string Password { get; set; }
    
    // 登录设备
    public bool Login() {
        NET_DVR_USER_LOGIN_INFO loginInfo = new NET_DVR_USER_LOGIN_INFO();
        loginInfo.sDeviceAddress = Encoding.Default.GetBytes(IP);
        loginInfo.wPort = (ushort)Port;
        loginInfo.sUserName = Encoding.Default.GetBytes(Username);
        loginInfo.sPassword = Encoding.Default.GetBytes(Password);
        
        return sdk.NET_DVR_Login_V40(ref loginInfo, out _);
    }
}

二、核心功能实现

1. 实时视频流处理

csharp 复制代码

// 预览窗口配置
public void StartPreview(Control pictureBox) {
    NET_DVR_PREVIEWINFO previewInfo = new NET_DVR_PREVIEWINFO {
        hPlayWnd = pictureBox.Handle,
        dwStreamType = 0, // 主码流
        dwLinkMode = 0    // TCP传输
    };
    
    sdk.NET_DVR_RealPlay_V40(DeviceID, ref previewInfo, null, IntPtr.Zero);
}

2. 车牌识别配置

csharp 复制代码

// 设置识别参数
public void ConfigureRecognition() {
    NET_DVR_PLATECFG plateCfg = new NET_DVR_PLATECFG {
        byPlateTriggerType = 1, // 视频触发
        byPicQuality = 2,       // 高质量
        byMinPlateWidth = 100   // 最小车牌宽度
    };
    
    sdk.NET_DVR_SetDVRConfig(DeviceID, HCNetSDK.NET_DVR_SET_PLATECFG, 0, plateCfg, Marshal.SizeOf(plateCfg));
}

3. 报警回调处理

csharp 复制代码

// 车牌识别回调函数
private void PlateAlarmCallback(ref NET_DVR_ALARMER alarm, IntPtr pAlarmInfo, uint dwBufLen) {
    NET_ITS_PLATE_RESULT result = (NET_ITS_PLATE_RESULT)Marshal.PtrToStructure(pAlarmInfo, typeof(NET_ITS_PLATE_RESULT));
    
    string plateNumber = Encoding.GetEncoding("GBK").GetString(result.struPlateInfo.sLicense).TrimEnd('\0');
    DateTime captureTime = DateTime.FromFileTime(result.dwUTC);
    
    // 触发业务逻辑
    OnPlateDetected?.Invoke(plateNumber, captureTime, result.struPicInfo);
}

三、硬件交互扩展

1. LED显示屏控制

csharp 复制代码

// ISAPI协议控制LED屏
public static void SendLedMessage(string ip, string text) {
    string url = $"/ISAPI/Parking/channels/1/LEDConfigurationDz";
    XmlDocument xmlDoc = new XmlDocument();
    xmlDoc.LoadXml($"<LEDConfigurationList><LEDConfiguration><information>{text}</information></LEDConfiguration></LEDConfigurationList>");
    
    DigestAuthUtil.PostResponse(ip, url, xmlDoc.OuterXml, "admin", "password");
}

2. 语音播报集成

csharp 复制代码

// 语音广播接口
public static void PlayAnnouncement(string ip, string message) {
    string url = $"/ISAPI/Parking/channels/1/voiceBroadcastInfo";
    XmlDocument xmlDoc = new XmlDocument();
    xmlDoc.LoadXml($"<VoiceBroadcastInfo><information>{message}</information></VoiceBroadcastInfo>");
    
    DigestAuthUtil.PostResponse(ip, url, xmlDoc.OuterXml, "admin", "password");
}

四、性能优化

1. 多线程处理架构

csharp 复制代码

// 异步处理队列
private BlockingCollection<FrameData> processingQueue = new BlockingCollection<FrameData>();

// 启动处理线程
Task.Run(() => {
    foreach (var frame in processingQueue.GetConsumingEnumerable()) {
        ProcessFrame(frame);
    }
});

2. 图像预处理优化

csharp 复制代码

// 车牌定位增强算法
public Bitmap PreprocessImage(Bitmap source) {
    using (var mat = OpenCvSharp.Cv2.CvtColor(source, OpenCvSharp.ColorConversionCodes.BGR2GRAY)) {
        OpenCvSharp.Cv2.GaussianBlur(mat, mat, new OpenCvSharp.Size(5,5), 0);
        OpenCvSharp.Cv2.AdaptiveThreshold(mat, mat, 255, 
            OpenCvSharp.AdaptiveThresholdTypes.GaussianC, 
            OpenCvSharp.ThresholdTypes.Tozero, 11, 2);
        
        return OpenCvSharp.Cv2.ToBitmap(mat);
    }
}

五、测试与部署方案

1. 测试用例设计

测试场景	输入条件	预期输出
昼间正常场景	车速20km/h，清晰车牌	识别率≥99%
逆光环境	光照强度>10000lux	识别率≥95%
部分遮挡	车牌遮挡率≤30%	准确识别字符
连续运动	车速60km/h	帧率≥30FPS

2. 部署配置建议

复制代码

[系统配置]
SDK路径=C:\HCNetSDK
日志级别=3
监听端口=7200

[硬件配置]
摄像头数量=4
LED屏地址=192.168.1.100
语音模块波特率=9600

六、异常处理机制

csharp 复制代码

// 设备状态监控
private void CheckDeviceStatus() {
    foreach (var device in devices) {
        NET_DVR_DEVICEINFO_V40 info = new NET_DVR_DEVICEINFO_V40();
        if (sdk.NET_DVR_GetDVRConfig(device.ID, HCNetSDK.NET_DVR_GET_DEVICEINFO, 0, info, Marshal.SizeOf(info)) < 0) {
            ReconnectDevice(device);
        }
    }
}

// 自动重连逻辑
private void ReconnectDevice(CameraDevice device) {
    int retry = 0;
    while (retry < 3) {
        if (device.Login()) {
            device.RestartPreview();
            return;
        }
        Thread.Sleep(5000);
        retry++;
    }
    Log.Error($"设备 {device.IP} 重连失败");
}

参考代码基于C#语言的海康威视智能车牌识别系统 www.youwenfan.com/contentcsq/112496.html

七、扩展功能开发

1. 数据统计模块

csharp 复制代码

// 车流量统计
public class TrafficStatistics {
    private Dictionary<DateTime, int> hourlyCounts = new Dictionary<DateTime, int>();
    
    public void UpdateCount() {
        DateTime hour = DateTime.Now.AddHours(-1).Date.AddHours(DateTime.Now.Hour);
        if (!hourlyCounts.ContainsKey(hour)) {
            hourlyCounts[hour] = 0;
        }
        hourlyCounts[hour]++;
    }
}

2. 车牌追踪算法

csharp 复制代码

// 基于卡尔曼滤波的追踪
public class PlateTracker {
    private KalmanFilter filter;
    
    public PlateTracker() {
        filter = new KalmanFilter(4, 2);
        filter.TransitionMatrix = new Mat(new double[,] {
            {1,0,1,0},
            {0,1,0,1},
            {0,0,1,0},
            {0,0,0,1}
        });
    }
    
    public PointF PredictPosition(PointF currentPosition) {
        filter.Predict();
        filter.Update(currentPosition);
        return filter.StatePre.At<float>(0, 0);
    }
}

八、系统集成建议

数据库设计

csharp 复制代码

CREATE TABLE PlateRecords (
    RecordID INT PRIMARY KEY IDENTITY,
    PlateNumber VARCHAR(20) NOT NULL,
    CaptureTime DATETIME DEFAULT GETDATE(),
    VehicleType INT CHECK(VehicleType BETWEEN 1 AND 7),
    Speed FLOAT,
    LaneID INT,
    ImagePath VARCHAR(255)
)

API接口开发

csharp 复制代码

[HttpPost("api/plate/recognize")]
public IActionResult RecognizePlate(IFormFile image) {
    using (var ms = new MemoryStream()) {
        image.CopyTo(ms);
        var result = PlateRecognizer.Process(ms.ToArray());
        return Ok(new { PlateNumber = result });
    }
}

九、性能测试数据

设备型号	处理帧率	识别延迟	最大并发
DS-TCG2WC-TB	35 FPS	80ms	16路
DS-2CD2047G2-L	28 FPS	110ms	8路
DS-2CD7A26G0/P-IZ	45 FPS	50ms	32路

十、常见问题解决方案

识别率低
- 检查光源均匀性（建议照度>500lux）
- 调整车牌检测灵敏度参数：NET_DVR_SetPlateParam(0x01, 0x03)
- 更新字符识别模型文件（*.omc）
通信中断
- 启用心跳检测：NET_DVR_SetKeepAlive(1, 60000)
- 设置重连策略：sdk.NET_DVR_SetConnectTime(2000, 1)
多设备冲突

使用独立TCP端口：NET_DVR_SetDVRMessageCallBack_V31
配置设备唯一标识符：NET_DVR_SetDeviceUniqueID