装了摄像头后一般会有 avicap32.dll文件，，没有一样可以用这些代码。

不需要在解决方案里面引用这个.dll文件。

下面有二种写法的例子：

例一：

using System;
using System.Runtime.InteropServices;
using System.Drawing;
using System.Drawing.Imaging;

namespace WinVideo
{
    /// <summary>
    /// webcam 的摘要说明。
    /// </summary>
    public class webcam
    {
        private const int WM_USER=0x400;
        private const int WS_CHILD=0x40000000;
        private const int WS_VISIBLE=0x10000000;
        private const int WM_CAP_START=WM_USER;
        private const int WM_CAP_STOP=WM_CAP_START + 68;
        private const int WM_CAP_DRIVER_CONNECT=WM_CAP_START + 10;
        private const int WM_CAP_DRIVER_DISCONNECT=WM_CAP_START + 11;
        private const int WM_CAP_SAVEDIB=WM_CAP_START + 25;
        private const int WM_CAP_GRAB_FRAME=WM_CAP_START + 60;
        private const int WM_CAP_SEQUENCE=WM_CAP_START + 62;
        private const int WM_CAP_FILE_SET_CAPTURE_FILEA=WM_CAP_START + 20;
        private const int WM_CAP_SEQUENCE_NOFILE=WM_CAP_START+ 63;
        private const int WM_CAP_SET_OVERLAY=WM_CAP_START+ 51;
        private const int WM_CAP_SET_PREVIEW=WM_CAP_START+ 50;
        private const int WM_CAP_SET_CALLBACK_VIDEOSTREAM=WM_CAP_START +6;
        private const int WM_CAP_SET_CALLBACK_ERROR=WM_CAP_START +2;
        private const int WM_CAP_SET_CALLBACK_STATUSA=WM_CAP_START +3;
        private const int WM_CAP_SET_CALLBACK_FRAME=WM_CAP_START +5;
        private const int WM_CAP_SET_SCALE=WM_CAP_START+ 53;
        private const int WM_CAP_SET_PREVIEWRATE=WM_CAP_START+ 52;
        private IntPtr hWndC;
        private bool bStat = false;

        private IntPtr mControlPtr;
        private int mWidth;
        private int mHeight;
        private int mLeft;
        private int mTop;
        private string GrabImagePath="";
        private string KinescopePath="";

        /// <summary>
        /// 初始化摄像头
        /// </summary>
        /// <param name="handle">控件的句柄</param>
        /// <param name="left">开始显示的左边距</param>
        /// <param name="top">开始显示的上边距</param>
        /// <param name="width">要显示的宽度</param>
        /// <param name="height">要显示的长度</param>
        public webcam(IntPtr handle,int left,int top,int width,int height)
        {
            mControlPtr=handle;
            mWidth=width;
            mHeight=height;
            mLeft=left;
            mTop=top;
        }
        "属性设置"

        [DllImport("avicap32.dll")]
        private static extern IntPtr capCreateCaptureWindowA(byte[] lpszWindowName,int dwStyle,int x,int y,int nWidth,int nHeight,IntPtr hWndParent,int nID);

        [DllImport("avicap32.dll")]
        private static extern int capGetVideoFormat(IntPtr hWnd,IntPtr psVideoFormat,int wSize );
        [DllImport("User32.dll")]
        private static extern bool SendMessage(IntPtr hWnd,int wMsg,int wParam,long lParam);

        /// <summary>
        /// 开始显示图像
        /// </summary>
        public void Start()
        {
            if(bStat)
                return;

            bStat=true;
            byte[] lpszName=new byte[100];

            hWndC=capCreateCaptureWindowA(lpszName,WS_CHILD|WS_VISIBLE ,mLeft,mTop,mWidth,mHeight,mControlPtr,0);

            if (hWndC.ToInt32()!=0)
            {
                SendMessage(hWndC,WM_CAP_SET_CALLBACK_VIDEOSTREAM,0,0);
                SendMessage(hWndC,WM_CAP_SET_CALLBACK_ERROR,0,0);
                SendMessage(hWndC,WM_CAP_SET_CALLBACK_STATUSA,0,0);
                SendMessage(hWndC,WM_CAP_DRIVER_CONNECT,0,0);
                SendMessage(hWndC,WM_CAP_SET_SCALE,1,0);
                SendMessage(hWndC,WM_CAP_SET_PREVIEWRATE,66,0);
                SendMessage(hWndC,WM_CAP_SET_OVERLAY,1,0);
                SendMessage(hWndC,WM_CAP_SET_PREVIEW,1,0);
            }
            return;
        }

        /// <summary>
        /// 停止显示
        /// </summary>
        public void Stop()
        {
            SendMessage(hWndC,WM_CAP_DRIVER_DISCONNECT,0,0);
            bStat=false;
        }

        /// <summary>
        /// 抓图
        /// </summary>
        /// <param name="path">要保存bmp文件的路径</param>
        public void GrabImage()
        {
            IntPtr hBmp=Marshal.StringToHGlobalAnsi(GrabImagePath);
            SendMessage(hWndC,WM_CAP_SAVEDIB,0,hBmp.ToInt64());

        }

        /// <summary>
        /// 录像
        /// </summary>
        /// <param name="path">要保存avi文件的路径</param>
        public void Kinescope()
        {
            IntPtr hBmp=Marshal.StringToHGlobalAnsi(KinescopePath);
            SendMessage(hWndC,WM_CAP_FILE_SET_CAPTURE_FILEA,0,hBmp.ToInt64());
            SendMessage(hWndC,WM_CAP_SEQUENCE,0,0);
        }

        /// <summary>
        /// 停止录像
        /// </summary>
        public void StopKinescope()
        {
            SendMessage(hWndC,WM_CAP_STOP,0,0);
        }
    }
}

对该类的调用：