read raw data from camera in csharp

main.cs
using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using DirectShowLib;

public class RawCameraData
{
    private IFilterGraph2 filterGraph;
    private ICaptureGraphBuilder2 captureGraphBuilder;
    private IAMVideoProcAmp videoProcAmp;

    public void StartCapture(int deviceIndex)
    {
        // Create the filter graph manager
        filterGraph = (IFilterGraph2)new FilterGraph();

        // Create the capture graph builder
        captureGraphBuilder = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();
        captureGraphBuilder.SetFiltergraph(filterGraph);

        // Get the camera device
        var device = GetCameraDevice(deviceIndex);

        // Add the camera to the filter graph
        var hr = filterGraph.AddSourceFilterForMoniker(device.Mon, null, device.Name, out var sourceFilter);
        DsError.ThrowExceptionForHR(hr);

        // Set the capture format to RAW
        var mt = new AMMediaType
        {
            majorType = MediaType.Video,
            subType = MediaSubType.RGB24
        };
        hr = captureGraphBuilder.FindInterface(PinCategory.Capture, MediaType.Video, sourceFilter, typeof(IAMStreamConfig).GUID, out var streamConfigObj);
        DsError.ThrowExceptionForHR(hr);
        var streamConfig = (IAMStreamConfig)streamConfigObj;
        hr = streamConfig.SetFormat(mt);
        DsError.ThrowExceptionForHR(hr);

        // Add the raw filter to the filter graph
        var rawFilter = (IBaseFilter)new NullRenderer();
        hr = filterGraph.AddFilter(rawFilter, "Raw Filter");
        DsError.ThrowExceptionForHR(hr);

        // Connect the camera to the raw filter
        hr = captureGraphBuilder.RenderStream(PinCategory.Capture, MediaType.Video, sourceFilter, null, rawFilter);
        DsError.ThrowExceptionForHR(hr);
    }

    public byte[] GetNextFrame()
    {
        // Retrieve the raw data from the raw filter's output pin
        var outputPin = (IPin)new NullRenderer().OutputPin;
        var mediaSample = GetNextSample(outputPin);
        if (mediaSample == null)
            return null;

        // Copy the raw data into a byte array
        IntPtr bufferPtr;
        mediaSample.GetPointer(out bufferPtr);
        var bufferSize = mediaSample.GetSize();
        var buffer = new byte[bufferSize];
        Marshal.Copy(bufferPtr, buffer, 0, bufferSize);

        Marshal.ReleaseComObject(mediaSample);

        return buffer;
    }

    private CameraDevice GetCameraDevice(int deviceIndex)
    {
        // Get the video input devices
        var devices = new FilterInfoCollection(FilterCategory.VideoInputDevice);
        if (deviceIndex >= devices.Count)
            throw new ArgumentOutOfRangeException(nameof(deviceIndex));

        // Select the specified camera device
        var device = devices[deviceIndex];

        return new CameraDevice
        {
            Mon = device.MonikerString,
            Name = device.Name
        };
    }

    private IMediaSample GetNextSample(IPin pin)
    {
        var mediaEvent = (IMediaEventEx)filterGraph;
        mediaEvent.WaitForCompletion(0, out var _);

        var sampleGrabber = (ISampleGrabber)new SampleGrabber();
        var hr = sampleGrabber.SetMediaType(new AMMediaType { majorType = MediaType.Video, subType = MediaSubType.RGB24 });
        DsError.ThrowExceptionForHR(hr);
        hr = filterGraph.AddFilter((IBaseFilter)sampleGrabber, "Sample Grabber");
        DsError.ThrowExceptionForHR(hr);
        hr = captureGraphBuilder.RenderStream(null, null, pin, sampleGrabber, null);
        DsError.ThrowExceptionForHR(hr);

        var mediaSample = (IMediaSample)new Sample();
        sampleGrabber.GetNextSample(mediaSample);

        filterGraph.RemoveFilter((IBaseFilter)sampleGrabber);

        if (mediaSample.GetActualDataLength() == 0)
            return null;

        return mediaSample;
    }

    private class CameraDevice
    {
        public string Mon { get; set; }
        public string Name { get; set; }
    }
}
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