[WPF 学习] 18. 摄像头（肢解DirectShow）

公司的产品需要人脸比对，摄像头相关的需求如下（突然发现除了英文不太好外，实际上中文也不太好，所以直接上一个接口）

using System;
using System.Drawing;
using System.Windows.Media;
namespace YK
{
    public enum ECameraAngle
    {
        A0,
        A90,
        A180,
        A270
    }
    public interface IVideo
    {
        /// <summary>
        /// 摄像头初始化
        /// </summary>
        /// <param name="index">摄像头序号</param>
        /// <param name="angle">摄像头角度</param>
        /// <param name="frameWidth">视频输出的宽度</param>
        /// <param name="frameHeight">视频输出的高度</param>
        /// <returns></returns>
        void Init(int index, int frameWidth = 640, int frameHeight = 480, ECameraAngle angle = ECameraAngle.A0);
        /// <summary>
        /// 打开摄像头
        /// </summary>
        void Play();
        /// <summary>
        /// 关闭摄像头
        /// </summary>
        void Stop();
        /// <summary>
        /// 新帧事件
        /// </summary>
        event Action<ImageSource> NewFrame;

        /// <summary>
        /// 获取当前帧
        /// </summary>
        Bitmap GetCurrentFrame();
    }
}

接口补充说明如下：

1. 命名空间yk：是我公司的简称，见笑。
2. 摄像头序号：公司的产品有时候有多个摄像头
3. 摄像头角度：公司的产品为了外观好看一点，有时候会转个90度

对应的Wpf的Xaml代码如下：

<Window x:Class="WpfAppVideoCapture.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfAppVideoCapture"
        mc:Ignorable="d"
         WindowState="Maximized"
        Title="MainWindow" Height="800" Width="800">
    <Grid>
        <Image Stretch="None" Source="{Binding Images}" Name="Video"></Image>
        <Button Content="Play" Click="Button_Click_1" Width="200" Height="100" VerticalAlignment="Bottom" Margin="0,0,500,0"></Button>
        <Button Content="Capture" Click="Button_Click_2" Width="200" Height="100" VerticalAlignment="Bottom" Margin="0,0,0,0"></Button>
        <Button Content="Stop" Click="Button_Click_3" Width="200" Height="100" VerticalAlignment="Bottom" Margin="500,0,0,0"></Button>
    </Grid>
</Window>

很简单，就是一个Image控件加三个Button控件（打开、拍照、停止）

对应的后台CS代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Media;

using YK;

namespace WpfAppVideoCapture
{
    public partial class MainWindow : Window
    {
        IVideo VC = new VideoCapture();
        VMMain VMMain = new VMMain();

        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = VMMain;

            VC.Init(0,640,480, ECameraAngle.A180);
            VC.NewFrame += VC_NewVideoSample;
            VC.Play();
        }


        private void VC_NewVideoSample(ImageSource imageSouce) => VMMain.Images = imageSouce;

        private void Button_Click_1(object sender, RoutedEventArgs e) => VC.Play();


        private void Button_Click_2(object sender, RoutedEventArgs e)
        {
            using var bitmap = VC.GetCurrentFrame();
            //人脸识别...
            bitmap.Save($@"d:	est{DateTime.Now.Ticks}.bmp", System.Drawing.Imaging.ImageFormat.Bmp);
        }

        private void Button_Click_3(object sender, RoutedEventArgs e) => VC.Stop();

    }

    public class VMMain : VMBase
    {
        public ImageSource Images
        {
            get => G<ImageSource>();
            set => S(value);

        }
    }
    public class VMBase : INotifyPropertyChanged
    {
        private readonly Dictionary<string, object> CDField = new Dictionary<string, object>();

        public event PropertyChangedEventHandler PropertyChanged;
        public void RaisePropertyChanged([CallerMemberName] string propertyName = "") => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        public T G<T>([CallerMemberName] string propertyName = "")
        {
            if (!CDField.TryGetValue(propertyName, out object _propertyValue))
            {
                _propertyValue = default(T);
                CDField.Add(propertyName, _propertyValue);
            }
            return (T)_propertyValue;
        }
        public void S(object value, [CallerMemberName] string propertyName = "")
        {
            if (!CDField.ContainsKey(propertyName) || CDField[propertyName] != (object)value)
            {
                CDField[propertyName] = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
}

没太多要说的，关键是实现了IVideo接口的VideoCapture类，下面来详细说说。

一、VideoCapture要用的一些类和接口(大部分对DirectShow封装，从DirectShowLib-2008复制并删减的)

using System;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Security;
namespace YK
{
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("56a86891-0ad4-11ce-b03a-0020af0ba770"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IPin
    {
    }
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("56a86895-0ad4-11ce-b03a-0020af0ba770"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IBaseFilter
    {
    }
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("56a868b1-0ad4-11ce-b03a-0020af0ba770"), InterfaceType(ComInterfaceType.InterfaceIsDual)]
    public interface IMediaControl
    {
        [PreserveSig]
        int Run();
        [PreserveSig]
        int Stop();
    }
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("56a8689f-0ad4-11ce-b03a-0020af0ba770"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IFilterGraph
    {
        [PreserveSig]
        int AddFilter([In] IBaseFilter pFilter, [In, MarshalAs(UnmanagedType.LPWStr)] string pName);
        [PreserveSig]
        int RemoveFilter([In] IBaseFilter pFilter);
        [PreserveSig]
        int EnumFilters([Out] out object ppEnum);
        [PreserveSig]
        int FindFilterByName([In, MarshalAs(UnmanagedType.LPWStr)] string pName, [Out] out IBaseFilter ppFilter);
        [PreserveSig]
        int ConnectDirect([In] IPin ppinOut, [In] IPin ppinIn, [In, MarshalAs(UnmanagedType.LPStruct)] AMMediaType pmt);
        [PreserveSig]
        [Obsolete("This method is obsolete; use the IFilterGraph2.ReconnectEx method instead.")]
        int Reconnect([In] IPin ppin);
        [PreserveSig]
        int Disconnect([In] IPin ppin);
        [PreserveSig]
        int SetDefaultSyncSource();
    }
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("56a868a9-0ad4-11ce-b03a-0020af0ba770"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IGraphBuilder : IFilterGraph
    {
        #region IFilterGraph Methods
        [PreserveSig]
        new int AddFilter([In] IBaseFilter pFilter, [In, MarshalAs(UnmanagedType.LPWStr)] string pName);
        [PreserveSig]
        new int RemoveFilter([In] IBaseFilter pFilter);
        [PreserveSig]
        new int EnumFilters([Out] out object ppEnum);
        [PreserveSig]
        new int FindFilterByName([In, MarshalAs(UnmanagedType.LPWStr)] string pName, [Out] out IBaseFilter ppFilter);
        [PreserveSig]
        new int ConnectDirect([In] IPin ppinOut, [In] IPin ppinIn, [In, MarshalAs(UnmanagedType.LPStruct)] AMMediaType pmt);
        [PreserveSig]
        new int Reconnect([In] IPin ppin);
        [PreserveSig]
        new int Disconnect([In] IPin ppin);
        [PreserveSig]
        new int SetDefaultSyncSource();
        #endregion
        [PreserveSig]
        int Connect([In] IPin ppinOut, [In] IPin ppinIn);
        [PreserveSig]
        int Render([In] IPin ppinOut);
        [PreserveSig]
        int RenderFile([In, MarshalAs(UnmanagedType.LPWStr)] string lpcwstrFile, [In, MarshalAs(UnmanagedType.LPWStr)] string lpcwstrPlayList);
        [PreserveSig]
        int AddSourceFilter([In, MarshalAs(UnmanagedType.LPWStr)] string lpcwstrFileName, [In, MarshalAs(UnmanagedType.LPWStr)] string lpcwstrFilterName, [Out] out IBaseFilter ppFilter);
        [PreserveSig]
        int SetLogFile(IntPtr hFile); // DWORD_PTR
        [PreserveSig]
        int Abort();
        [PreserveSig]
        int ShouldOperationContinue();
    }
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("36b73882-c2c8-11cf-8b46-00805f6cef60"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IGraphBuilder2 : IGraphBuilder
    {
        #region IFilterGraph Methods
        [PreserveSig]
        new int AddFilter([In] IBaseFilter pFilter, [In, MarshalAs(UnmanagedType.LPWStr)] string pName);
        [PreserveSig]
        new int RemoveFilter([In] IBaseFilter pFilter);
        [PreserveSig]
        new int EnumFilters([Out] out object ppEnum);
        [PreserveSig]
        new int FindFilterByName([In, MarshalAs(UnmanagedType.LPWStr)] string pName, [Out] out IBaseFilter ppFilter);
        [PreserveSig]
        new int ConnectDirect([In] IPin ppinOut, [In] IPin ppinIn, [In, MarshalAs(UnmanagedType.LPStruct)] AMMediaType pmt);
        [PreserveSig]
        new int Reconnect([In] IPin ppin);
        [PreserveSig]
        new int Disconnect([In] IPin ppin);
        [PreserveSig]
        new int SetDefaultSyncSource();
        #endregion
        #region IGraphBuilder Method
        [PreserveSig]
        new int Connect([In] IPin ppinOut, [In] IPin ppinIn);
        [PreserveSig]
        new int Render([In] IPin ppinOut);
        [PreserveSig]
        new int RenderFile([In, MarshalAs(UnmanagedType.LPWStr)] string lpcwstrFile, [In, MarshalAs(UnmanagedType.LPWStr)] string lpcwstrPlayList);
        [PreserveSig]
        new int AddSourceFilter([In, MarshalAs(UnmanagedType.LPWStr)] string lpcwstrFileName, [In, MarshalAs(UnmanagedType.LPWStr)] string lpcwstrFilterName, [Out] out IBaseFilter ppFilter);
        [PreserveSig]
        new int SetLogFile(IntPtr hFile); // DWORD_PTR
        [PreserveSig]
        new int Abort();
        [PreserveSig]
        new int ShouldOperationContinue();
        #endregion
        [PreserveSig]
        int AddSourceFilterForMoniker([In] IMoniker pMoniker, [In] IBindCtx pCtx, [In, MarshalAs(UnmanagedType.LPWStr)] string lpcwstrFilterName, [Out] out IBaseFilter ppFilter);
    }
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("93E5A4E0-2D50-11d2-ABFA-00A0C9C6E38D"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface ICaptureGraphBuilder2
    {
        [PreserveSig]
        int SetFiltergraph([In] IGraphBuilder pfg);
        [PreserveSig]
        int GetFiltergraph([Out] out IGraphBuilder ppfg);
        [PreserveSig]
        int SetOutputFileName([In, MarshalAs(UnmanagedType.LPStruct)] Guid pType, [In, MarshalAs(UnmanagedType.LPWStr)] string lpstrFile, [Out] out IBaseFilter ppbf, [Out] out object ppSink);
        [PreserveSig]
        int FindInterface([In, MarshalAs(UnmanagedType.LPStruct)] Guid pCategory, [In, MarshalAs(UnmanagedType.LPStruct)] Guid pType, [In] IBaseFilter pbf, [In, MarshalAs(UnmanagedType.LPStruct)] Guid riid, [Out, MarshalAs(UnmanagedType.IUnknown)] out object ppint);
        [PreserveSig]
        int RenderStream([In, MarshalAs(UnmanagedType.LPStruct)] Guid PinCategory, [In, MarshalAs(UnmanagedType.LPStruct)] Guid MediaType, [In, MarshalAs(UnmanagedType.IUnknown)] object pSource, [In] IBaseFilter pfCompressor, [In] IBaseFilter pfRenderer);
    }

    [ComImport, SuppressUnmanagedCodeSecurity, Guid("6B652FFF-11FE-4fce-92AD-0266B5D7C78F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface ISampleGrabber
    {
        [PreserveSig]
        int SetOneShot([In, MarshalAs(UnmanagedType.Bool)] bool OneShot);
        [PreserveSig]
        int SetMediaType([In, MarshalAs(UnmanagedType.LPStruct)] AMMediaType pmt);
        [PreserveSig]
        int GetConnectedMediaType([Out, MarshalAs(UnmanagedType.LPStruct)] AMMediaType pmt);
        [PreserveSig]
        int SetBufferSamples([In, MarshalAs(UnmanagedType.Bool)] bool BufferThem);
        [PreserveSig]
        int GetCurrentBuffer(ref int pBufferSize, IntPtr pBuffer);
        [PreserveSig]
        int GetCurrentSample(out IntPtr ppSample);
        [PreserveSig]
        int SetCallback(ISampleGrabberCB pCallback, int WhichMethodToCallback);
    }
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("0579154A-2B53-4994-B0D0-E773148EFF85"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface ISampleGrabberCB
    {
        [PreserveSig]
        int SampleCB(double SampleTime, IntPtr pSample);
        [PreserveSig]
        int BufferCB(double SampleTime, IntPtr pBuffer, int BufferLen);
    }
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("29840822-5B84-11D0-BD3B-00A0C911CE86"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface ICreateDevEnum
    {
        [PreserveSig]
        int CreateClassEnumerator([In, MarshalAs(UnmanagedType.LPStruct)] Guid pType, [Out] out IEnumMoniker ppEnumMoniker, [In] int dwFlags);
    }
    [ComImport, SuppressUnmanagedCodeSecurity, Guid("C6E13340-30AC-11d0-A18C-00A0C9118956"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IAMStreamConfig
    {
        [PreserveSig]
        int SetFormat([In, MarshalAs(UnmanagedType.LPStruct)] AMMediaType pmt);
        [PreserveSig]
        int GetFormat([Out] out AMMediaType pmt);
    }
    [StructLayout(LayoutKind.Sequential)]
    public class AMMediaType
    {
        public Guid majorType;
        public Guid subType;
        [MarshalAs(UnmanagedType.Bool)] public bool fixedSizeSamples;
        [MarshalAs(UnmanagedType.Bool)] public bool temporalCompression;
        public int sampleSize;
        public Guid formatType;
        public IntPtr unkPtr; // IUnknown Pointer
        public int formatSize;
        public IntPtr formatPtr; // Pointer to a buff determined by formatType 指向VideoInfo
    }
    [ComImport, Guid("e436ebb8-524f-11ce-9f53-0020af0ba770")]
    public class FilterGraphNoThread
    {
    }
    [ComImport, Guid("BF87B6E1-8C27-11d0-B3F0-00AA003761C5")]
    public class CaptureGraphBuilder2
    {
    }
    [StructLayout(LayoutKind.Sequential)]
    public class DsRect
    {
        public int left;
        public int top;
        public int right;
        public int bottom;
    }
    [StructLayout(LayoutKind.Sequential)]
    public class VideoInfoHeader
    {
        public DsRect SrcRect;
        public DsRect TargetRect;
        public int BitRate;
        public int BitErrorRate;
        public long AvgTimePerFrame;
        public BitmapInfoHeader BmiHeader;
    }
    [StructLayout(LayoutKind.Sequential, Pack = 2)]
    public class BitmapInfoHeader
    {
        public int Size;//本结构大小40字节
        public int Width;
        public int Height;
        public short Planes;
        public short BitCount;
        public int Compression;
        public int ImageSize;
        public int XPelsPerMeter;
        public int YPelsPerMeter;
        public int ClrUsed;
        public int ClrImportant;
    }
    [ComImport, Guid("C1F400A0-3F08-11d3-9F0B-006008039E37")]
    public class SampleGrabber
    {
    }
    [ComImport, Guid("62BE5D10-60EB-11d0-BD3B-00A0C911CE86")]
    public class CreateDevEnum
    {
    }
}

二、VideoCapture的using

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;

三、VideoCapture的继承的接口

    public class VideoCapture : ISampleGrabberCB, IDisposable, IVideo

四、VideoCapture的一些字段和一个Com封装

        [DllImport("Kernel32.dll", EntryPoint = "RtlMoveMemory")]
        private static extern void CopyMemory(IntPtr destination, IntPtr source, [MarshalAs(UnmanagedType.U4)] int length);

        private readonly Guid Capture = new Guid(0xfb6c4281, 0x0353, 0x11d1, 0x90, 0x5f, 0x00, 0x00, 0xc0, 0xcc, 0x16, 0xba);
        private readonly Guid Video = new Guid(0x73646976, 0x0000, 0x0010, 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71);
        private readonly Guid VideoInfo = new Guid(0x05589f80, 0xc356, 0x11ce, 0xbf, 0x01, 0x00, 0xaa, 0x00, 0x55, 0x59, 0x5a);
        private readonly Guid RGB24 = new Guid(0xe436eb7d, 0x524f, 0x11ce, 0x9f, 0x53, 0x00, 0x20, 0xaf, 0x0b, 0xa7, 0x70);
        private readonly Guid VideoInputDevice = new Guid(0x860BB310, 0x5D01, 0x11d0, 0xBD, 0x3B, 0x00, 0xA0, 0xC9, 0x11, 0xCE, 0x86);
        private readonly IMediaControl _MediaControl = (IMediaControl)new FilterGraphNoThread();
        private readonly ISampleGrabber _SampleGrabber = (ISampleGrabber)new SampleGrabber();
        private readonly BitmapPalette _BitmapPalette = new BitmapPalette(new List<System.Windows.Media.Color> { Colors.Red, Colors.Blue, Colors.Green });

        private int _FrameWidth, _FrameHeight, _FrameBufferSize;
        private IntPtr _PSampleBuffer;
        private Rectangle _RectangleSource, _RectangleDestination;
        private RotateFlipType _RotateFlipType;

        private bool _Grabbing;

        public event Action<ImageSource> NewFrame;

五、实现IVideo的Init方法

        public void Init(int cameraIndex, int frameWidth = 640, int frameHeight = 480, ECameraAngle angle = ECameraAngle.A0)
        {
            _FrameWidth = frameWidth;
            _FrameHeight = frameHeight;
            _FrameBufferSize = frameWidth * frameHeight * 3;
            _PSampleBuffer = Marshal.AllocCoTaskMem(_FrameBufferSize);
            _RectangleSource = new Rectangle(0, 0, frameWidth, frameHeight);
            switch (angle)
            {
                case ECameraAngle.A0:
                    _RectangleDestination = _RectangleSource;
                    _RotateFlipType = RotateFlipType.RotateNoneFlipXY;
                    break;
                case ECameraAngle.A90:
                    _RotateFlipType = RotateFlipType.Rotate90FlipNone;
                    _RectangleDestination = new Rectangle(0, 0, _FrameHeight, _FrameWidth);
                    break;
                case ECameraAngle.A270:
                    _RotateFlipType = RotateFlipType.Rotate270FlipNone;
                    _RectangleDestination = new Rectangle(0, 0, _FrameHeight, _FrameWidth);
                    break;
                case ECameraAngle.A180:
                    _RotateFlipType = RotateFlipType.RotateNoneFlipNone;
                    break;
            }

            var graphBuilder = (IGraphBuilder)_MediaControl;
            var captureGraphBuilder2 = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();
            int hr = captureGraphBuilder2.SetFiltergraph(graphBuilder);
            ThrowExceptionForHR(hr);

            //此方法可以将 source filter 上的 output pin 连接到 sink filter，也可以通过中间 filter 连接。
            hr = captureGraphBuilder2.RenderStream(Capture,//[in]指向 AMPROPERTY_PIN_CATEGORY 属性集中的 pin 类别的指针（请参见 Pin属性集）。PIN_CATEGORY_CAPTURE、PIN_CATEGORY_PREVIEW、PIN_CATEGORY_CC
                                         Video,//[in]指向主要类型 GUID 的指针，该 GUID 指定输出 pin 的媒体类型；或 NULL 以使用任何 pin，而与媒体类型无关。有关可能值的列表，请参考 Media Types and Sub Types。
                                         SetupCamera(cameraIndex, captureGraphBuilder2, (IGraphBuilder2)graphBuilder),//[in]指定一个指向连接的起始 filter 或输出 pin 的指针。
                                         SetupSampleGrabber(graphBuilder, _SampleGrabber),//[in]指向中间 filter （例如压缩 filter）的 IBaseFilter 接口的指针。可以为 NULL。
                                         null);//[in]指向 sink filter（例如 renderer 或 mux filter）的 IBaseFilter 接口的指针。如果值为 NULL，则该方法使用默认的 renderer（渲染器）。
            ThrowExceptionForHR(hr);
            Marshal.ReleaseComObject(captureGraphBuilder2);
        }

除了一些字段的初始化以外，就是创建CamerFilter和SampleGrabberFilter，并把这两个Filter加入到FilterGraphNoThread，最后由CaptureGraphBuilder2揉一揉。

1. CamerFilter创建的代码是这样的

        private IBaseFilter SetupCamera(int cameraIndex, ICaptureGraphBuilder2 captureGraphBuilder2, IGraphBuilder2 graphBuilder2)
        {
            ICreateDevEnum enumDev = (ICreateDevEnum)new CreateDevEnum();
            int hr = enumDev.CreateClassEnumerator(VideoInputDevice, out IEnumMoniker enumMon, 0);
            ThrowExceptionForHR(hr);

            IMoniker[] mon = new IMoniker[1];
            if (cameraIndex > 0)
            {
                hr = enumMon.Skip(cameraIndex);
                ThrowExceptionForHR(hr);
            }
            hr = enumMon.Next(1, mon, IntPtr.Zero);
            ThrowExceptionForHR(hr);

            hr = graphBuilder2.AddSourceFilterForMoniker(mon[0], null, "Camera", out IBaseFilter filterCamera);
            ThrowExceptionForHR(hr);

            if (filterCamera is null)
                throw new Exception($"无法连接摄像头{cameraIndex}");


            hr = captureGraphBuilder2.FindInterface(Capture, Video, filterCamera, typeof(IAMStreamConfig).GUID, out var streamConfig);
            ThrowExceptionForHR(hr);

            var videoStreamConfig = streamConfig as IAMStreamConfig;

            hr = videoStreamConfig.GetFormat(out var media);
            ThrowExceptionForHR(hr);

            var videoInfo = new VideoInfoHeader();
            Marshal.PtrToStructure(media.formatPtr, videoInfo);
            videoInfo.BmiHeader.Width = _FrameWidth;
            videoInfo.BmiHeader.Height = _FrameHeight;
            Marshal.StructureToPtr(videoInfo, media.formatPtr, false);

            hr = videoStreamConfig.SetFormat(media);
            Marshal.FreeHGlobal(media.formatPtr);
            if (hr < 0)
                throw new Exception($"摄像头不支持{_FrameWidth}*{_FrameHeight}");

            return filterCamera;

        }

2. SampleGrabberFilter创建的代码是这样的

        private IBaseFilter SetupSampleGrabber(IGraphBuilder graphBuilder, ISampleGrabber sampleGrabber)
        {
            var mediaType = new AMMediaType
            {
                majorType = Video,
                subType = RGB24,
                formatType = VideoInfo
            };

            int hr = sampleGrabber.SetMediaType(mediaType);
            ThrowExceptionForHR(hr);

            hr = sampleGrabber.SetBufferSamples(true);
            ThrowExceptionForHR(hr);

            var filterGrabber = _SampleGrabber as IBaseFilter;
            hr = graphBuilder.AddFilter(filterGrabber, "SampleGrabber");
            ThrowExceptionForHR(hr);

            return filterGrabber;
        }

3.还有一个报异常方法（讲真，只要是错误的hr我肯定不知道什么意思）

        private void ThrowExceptionForHR(int hr, [CallerMemberName] string memberName = "", [CallerLineNumber] int lineNumber = 0)
        {
            if (hr < 0)
                throw new Exception($"{memberName}/{lineNumber}错误：" + hr);
        }

六、实现IVideo的Play和Stop方法

        public void Play()
        {
            if (!Application.Current.Dispatcher.CheckAccess())
            {
                Application.Current.Dispatcher.Invoke(() => Play());
                return;
            }
            _SampleGrabber.SetCallback(this, 1);
            _MediaControl.Run();
        }
        public async void Stop()
        {
            if (!Application.Current.Dispatcher.CheckAccess())
            {
                Application.Current.Dispatcher.Invoke(() => Stop());
                return;
            }
            _SampleGrabber.SetCallback(null, 1);

            while (_Grabbing)
                await Task.Delay(5);
            NewFrame?.Invoke(null);
            _MediaControl.Stop();
        }

六、实现ISampleGrabberCB的第0个方法SampleCB(VideoCapture不调用，所以直接返回0)

public int SampleCB(double SampleTime, IntPtr pSample) => 0;

七、实现ISampleGrabberCB的第1个方法BufferCB

        public int BufferCB(double SampleTime, IntPtr pBuffer, int BufferLen)
        {
            if (NewFrame != null)
            {
                _Grabbing = true;
                if (_RotateFlipType == RotateFlipType.RotateNoneFlipNone)
                    Application.Current.Dispatcher.Invoke(() => NewFrame?.Invoke(BitmapSource.Create(_FrameWidth, _FrameHeight, 96, 96, PixelFormats.Bgr24, _BitmapPalette, pBuffer, _FrameBufferSize, _FrameWidth * 3)));
                else
                {
                    using var bitmap = new Bitmap(_FrameWidth, _FrameHeight);
                    var bmpData = bitmap.LockBits(_RectangleSource, ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
                    CopyMemory(bmpData.Scan0, pBuffer, _FrameBufferSize);
                    bitmap.UnlockBits(bmpData);
                    bitmap.RotateFlip(_RotateFlipType);
                    bmpData = bitmap.LockBits(_RectangleDestination, ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
                    Application.Current.Dispatcher.Invoke(() => NewFrame?.Invoke(BitmapSource.Create(_RectangleDestination.Width, _RectangleDestination.Height, 96, 96, PixelFormats.Bgr24, _BitmapPalette, bmpData.Scan0, _FrameBufferSize, _RectangleDestination.Width * 3)));
                    bitmap.UnlockBits(bmpData);
                }
                _Grabbing = false;
            }
            return 0;
        }

八、最后实现IDisposable的Dispose方法

        public void Dispose()
        {
            Marshal.ReleaseComObject(_MediaControl);
            Marshal.ReleaseComObject(_SampleGrabber);
            if (_PSampleBuffer != IntPtr.Zero)
                Marshal.FreeCoTaskMem(_PSampleBuffer);
        }

看了一下，VideoCapture类不到600行，复制起来也容易；编译后17K，相当小巧。虽然说是WPF的，其实稍加改动Winform也能用。

哦，整个项目发布在(gittee)[https://gitee.com/catzhou/video-capture]，欢迎点赞！