5 lines of code sample - Video preview for web camera with frame capture - VisioForge Video Capture SDK .Net - https://www.visioforge.com/video-capture-sdk-net

CameraPreviewFrameSave.cs

// Required NuGet packages: 
// https://www.nuget.org/packages/VisioForge.DotNet.VideoCapture/
// https://www.nuget.org/packages/VisioForge.DotNet.Core.Redist.VideoCapture.x64/
// https://www.nuget.org/packages/VisioForge.DotNet.Core.Redist.VideoCapture.x86/

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

using VisioForge.Types.OutputFormat;

namespace SampleCapture
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            
            videoCapture1.OnError += OnError;
        }

        private void btStart_Click(object sender, EventArgs e)
        {
            videoCapture1.Video_CaptureDevice = videoCapture1.Video_CaptureDevicesInfo[0].Name;
            videoCapture1.Audio_CaptureDevice = videoCapture1.Audio_CaptureDevicesInfo[0].Name;
            videoCapture1.Mode = VisioForge.Types.VFVideoCaptureMode.VideoPreview;
            videoCapture1.Start();
        }

        private void btStop_Click(object sender, EventArgs e)
        {
            videoCapture1.Stop();
        }

        private void btSaveFrame_Click(object sender, EventArgs e)
        {
            videoCapture1.Frame_Save(Environment.GetFolderPath(Environment.SpecialFolder.MyPictures) + "\\frame.jpg", VisioForge.Types.VFImageFormat.JPEG, 85);
        }
        
        private void OnError(object sender, ErrorsEventArgs e)
        {
            System.Diagnostics.Debug.WriteLine(e.Message);
        }
    }
}