如何使用 C# .NET 将屏幕捕获为视频？

是否有一些库可以将屏幕捕获为压缩视频文件或可以执行此操作的某种解决方案？

此代码使用 NuGet 上提供的 SharpAvi。

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Threading;
using System.Threading.Tasks;
using SharpAvi;
using SharpAvi.Codecs;
using SharpAvi.Output;
using System.Windows.Forms;

namespace Captura
{
    // Used to Configure the Recorder
    public class RecorderParams
    {
        public RecorderParams(string filename, int FrameRate, FourCC Encoder, int Quality)
        {
            FileName = filename;
            FramesPerSecond = FrameRate;
            Codec = Encoder;
            this.Quality = Quality;

            Height = Screen.PrimaryScreen.Bounds.Height;
            Width = Screen.PrimaryScreen.Bounds.Width;
        }

        string FileName;
        public int FramesPerSecond, Quality;
        FourCC Codec;

        public int Height { get; private set; }
        public int Width { get; private set; }

        public AviWriter CreateAviWriter()
        {
            return new AviWriter(FileName)
            {
                FramesPerSecond = FramesPerSecond,
                EmitIndex1 = true,
            };
        }

        public IAviVideoStream CreateVideoStream(AviWriter writer)
        {
            // Select encoder type based on FOURCC of codec
            if (Codec == KnownFourCCs.Codecs.Uncompressed)
                return writer.AddUncompressedVideoStream(Width, Height);
            else if (Codec == KnownFourCCs.Codecs.MotionJpeg)
                return writer.AddMotionJpegVideoStream(Width, Height, Quality);
            else
            {
                return writer.AddMpeg4VideoStream(Width, Height, (double)writer.FramesPerSecond,
                    // It seems that all tested MPEG-4 VfW codecs ignore the quality affecting parameters passed through VfW API
                    // They only respect the settings from their own configuration dialogs, and Mpeg4VideoEncoder currently has no support for this
                    quality: Quality,
                    codec: Codec,
                    // Most of VfW codecs expect single-threaded use, so we wrap this encoder to special wrapper
                    // Thus all calls to the encoder (including its instantiation) will be invoked on a single thread although encoding (and writing) is performed asynchronously
                    forceSingleThreadedAccess: true);
            }
        }
    }

    public class Recorder : IDisposable
    {
        #region Fields
        AviWriter writer;
        RecorderParams Params;
        IAviVideoStream videoStream;
        Thread screenThread;
        ManualResetEvent stopThread = new ManualResetEvent(false);
        #endregion

        public Recorder(RecorderParams Params)
        {
            this.Params = Params;

            // Create AVI writer and specify FPS
            writer = Params.CreateAviWriter();

            // Create video stream
            videoStream = Params.CreateVideoStream(writer);
            // Set only name. Other properties were when creating stream, 
            // either explicitly by arguments or implicitly by the encoder used
            videoStream.Name = "Captura";

            screenThread = new Thread(RecordScreen)
            {
                Name = typeof(Recorder).Name + ".RecordScreen",
                IsBackground = true
            };

            screenThread.Start();
        }

        public void Dispose()
        {
            stopThread.Set();
            screenThread.Join();

            // Close writer: the remaining data is written to a file and file is closed
            writer.Close();

            stopThread.Dispose();
        }

        void RecordScreen()
        {
            var frameInterval = TimeSpan.FromSeconds(1 / (double)writer.FramesPerSecond);
            var buffer = new byte[Params.Width * Params.Height * 4];
            Task videoWriteTask = null;
            var timeTillNextFrame = TimeSpan.Zero;

            while (!stopThread.WaitOne(timeTillNextFrame))
            {
                var timestamp = DateTime.Now;

                Screenshot(buffer);

                // Wait for the previous frame is written
                videoWriteTask?.Wait();

                // Start asynchronous (encoding and) writing of the new frame
                videoWriteTask = videoStream.WriteFrameAsync(true, buffer, 0, buffer.Length);

                timeTillNextFrame = timestamp + frameInterval - DateTime.Now;
                if (timeTillNextFrame < TimeSpan.Zero)
                    timeTillNextFrame = TimeSpan.Zero;
            }

            // Wait for the last frame is written
            videoWriteTask?.Wait();
        }

        public void Screenshot(byte[] Buffer)
        {
            using (var BMP = new Bitmap(Params.Width, Params.Height))
            {
                using (var g = Graphics.FromImage(BMP))
                {
                    g.CopyFromScreen(Point.Empty, Point.Empty, new Size(Params.Width, Params.Height), CopyPixelOperation.SourceCopy);

                    g.Flush();

                    var bits = BMP.LockBits(new Rectangle(0, 0, Params.Width, Params.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppRgb);
                    Marshal.Copy(bits.Scan0, Buffer, 0, Buffer.Length);
                    BMP.UnlockBits(bits);
                }
            }
        }
    }
}

用法示例

1. 创建一个控制台应用程序。
2. 添加参考System.Drawing and System.Windows.Forms。 （使用System.Windows.Forms如果修改代码就可以避免）。
3. 从 NuGet 安装 SharpAvi。

Code:

using Captura;
using System;

namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            // Using MotionJpeg as Avi encoder,
            // output to 'out.avi' at 10 Frames per second, 70% quality
            var rec = new Recorder(new RecorderParams("out.avi", 10, SharpAvi.KnownFourCCs.Codecs.MotionJpeg, 70));

            Console.WriteLine("Press any key to Stop...");
            Console.ReadKey();

            // Finish Writing
            rec.Dispose();
        }
    }
}