better-genshin-impact/BetterGenshinImpact/Core/Video/SharpAviRecorder.cs

using NAudio.Wave;
using SharpAvi.Codecs;
using SharpAvi.Output;
using System;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Interop;
using SharpAvi;
using FourCC = SharpAvi.FourCC;
using WaveFormat = NAudio.Wave.WaveFormat;

namespace BetterGenshinImpact.Core.Video;

public class SharpAviRecorder : IDisposable
{
    // public static readonly FourCC MJPEG_IMAGE_SHARP = "IMG#";

    private readonly int screenWidth;
    private readonly int screenHeight;
    private readonly AviWriter writer;
    private readonly IAviVideoStream videoStream;
    private readonly IAviAudioStream audioStream;
    private readonly WaveInEvent audioSource;
    private readonly Thread screenThread;
    private readonly ManualResetEvent stopThread = new ManualResetEvent(false);
    private readonly AutoResetEvent videoFrameWritten = new AutoResetEvent(false);
    private readonly AutoResetEvent audioBlockWritten = new AutoResetEvent(false);

    public SharpAviRecorder(string fileName,
        FourCC codec, int quality,
        int audioSourceIndex, SupportedWaveFormat audioWaveFormat, bool encodeAudio, int audioBitRate)
    {
        System.Windows.Media.Matrix toDevice;
        using (var source = new HwndSource(new HwndSourceParameters()))
        {
            toDevice = source.CompositionTarget.TransformToDevice;
        }

        screenWidth = (int)Math.Round(SystemParameters.PrimaryScreenWidth * toDevice.M11);
        screenHeight = (int)Math.Round(SystemParameters.PrimaryScreenHeight * toDevice.M22);

        // Create AVI writer and specify FPS
        writer = new AviWriter(fileName)
        {
            FramesPerSecond = 60,
            EmitIndex1 = true,
        };

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

        if (audioSourceIndex >= 0)
        {
            var waveFormat = ToWaveFormat(audioWaveFormat);

            audioStream = CreateAudioStream(waveFormat, encodeAudio, audioBitRate);
            // Set only name. Other properties were when creating stream, 
            // either explicitly by arguments or implicitly by the encoder used
            audioStream.Name = "Voice";

            audioSource = new WaveInEvent
            {
                DeviceNumber = audioSourceIndex,
                WaveFormat = waveFormat,
                // Buffer size to store duration of 1 frame
                BufferMilliseconds = (int)Math.Ceiling(1000 / writer.FramesPerSecond),
                NumberOfBuffers = 3,
            };
            audioSource.DataAvailable += audioSource_DataAvailable;
        }

        screenThread = new Thread(RecordScreen)
        {
            Name = typeof(SharpAviRecorder).Name + ".RecordScreen",
            IsBackground = true
        };
    }
    
    public void Start()
    {
        if (audioSource != null)
        {
            videoFrameWritten.Set();
            audioBlockWritten.Reset();
            audioSource.StartRecording();
        }

        screenThread.Start();
    }

    private IAviVideoStream CreateVideoStream(FourCC codec, int quality)
    {
        // Select encoder type based on FOURCC of codec
        if (codec == CodecIds.Uncompressed)
        {
            return writer.AddUncompressedVideoStream(screenWidth, screenHeight);
        }
        else if (codec == CodecIds.MotionJpeg)
        {
            // Use M-JPEG based on WPF (Windows only)
            return writer.AddMJpegWpfVideoStream(screenWidth, screenHeight, quality);
        }
        // else if (codec == MJPEG_IMAGE_SHARP)
        // {
        //     // Use M-JPEG based on the SixLabors.ImageSharp package (cross-platform)
        //     // Included in the SharpAvi.ImageSharp package
        //     return writer.AddMJpegImageSharpVideoStream(screenWidth, screenHeight, quality);
        // }
        else
        {
            return writer.AddMpeg4VcmVideoStream(screenWidth, screenHeight, (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);
        }
    }

    private IAviAudioStream CreateAudioStream(WaveFormat waveFormat, bool encode, int bitRate)
    {
        // Create encoding or simple stream based on settings
        if (encode)
        {
            // LAME DLL path is set in App.OnStartup()
            return writer.AddMp3LameAudioStream(waveFormat.Channels, waveFormat.SampleRate, bitRate);
        }
        else
        {
            return writer.AddAudioStream(
                channelCount: waveFormat.Channels,
                samplesPerSecond: waveFormat.SampleRate,
                bitsPerSample: waveFormat.BitsPerSample);
        }
    }

    private static WaveFormat ToWaveFormat(SupportedWaveFormat waveFormat)
    {
        switch (waveFormat)
        {
            case SupportedWaveFormat.WAVE_FORMAT_44M16:
                return new WaveFormat(44100, 16, 1);
            case SupportedWaveFormat.WAVE_FORMAT_44S16:
                return new WaveFormat(44100, 16, 2);
            default:
                throw new NotSupportedException("Wave formats other than '16-bit 44.1kHz' are not currently supported.");
        }
    }

    public void Dispose()
    {
        stopThread.Set();
        screenThread.Join();
        if (audioSource != null)
        {
            audioSource.StopRecording();
            audioSource.DataAvailable -= audioSource_DataAvailable;
        }

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

        stopThread.Close();
    }

    private void RecordScreen()
    {
        var stopwatch = new Stopwatch();
        var buffer = new byte[screenWidth * screenHeight * 4];
        Task videoWriteTask = null;
        var isFirstFrame = true;
        var shotsTaken = 0;
        var timeTillNextFrame = TimeSpan.Zero;
        stopwatch.Start();

        while (!stopThread.WaitOne(timeTillNextFrame))
        {
            GetScreenshot(buffer);
            shotsTaken++;

            // Wait for the previous frame is written
            if (!isFirstFrame)
            {
                videoWriteTask.Wait();
                videoFrameWritten.Set();
            }

            if (audioStream != null)
            {
                var signalled = WaitHandle.WaitAny(new WaitHandle[] { audioBlockWritten, stopThread });
                if (signalled == 1)
                    break;
            }

            // Start asynchronous (encoding and) writing of the new frame
            // Overloads with Memory parameters are available on .NET 5+
#if NET5_0_OR_GREATER
            videoWriteTask = videoStream.WriteFrameAsync(true, buffer.AsMemory(0, buffer.Length));
#else
                videoWriteTask = videoStream.WriteFrameAsync(true, buffer, 0, buffer.Length);
#endif

            timeTillNextFrame = TimeSpan.FromSeconds(shotsTaken / (double)writer.FramesPerSecond - stopwatch.Elapsed.TotalSeconds);
            if (timeTillNextFrame < TimeSpan.Zero)
                timeTillNextFrame = TimeSpan.Zero;

            isFirstFrame = false;
        }

        stopwatch.Stop();

        // Wait for the last frame is written
        if (!isFirstFrame)
        {
            videoWriteTask.Wait();
        }
    }

    private void GetScreenshot(byte[] buffer)
    {
        using (var bitmap = new Bitmap(screenWidth, screenHeight))
        using (var graphics = Graphics.FromImage(bitmap))
        {
            graphics.CopyFromScreen(0, 0, 0, 0, new System.Drawing.Size(screenWidth, screenHeight));
            var bits = bitmap.LockBits(new Rectangle(0, 0, screenWidth, screenHeight), ImageLockMode.ReadOnly, PixelFormat.Format32bppRgb);
            Marshal.Copy(bits.Scan0, buffer, 0, buffer.Length);
            bitmap.UnlockBits(bits);

            // Should also capture the mouse cursor here, but skipping for simplicity
            // For those who are interested, look at http://www.codeproject.com/Articles/12850/Capturing-the-Desktop-Screen-with-the-Mouse-Cursor
        }
    }

    private void audioSource_DataAvailable(object sender, WaveInEventArgs e)
    {
        var signalled = WaitHandle.WaitAny(new WaitHandle[] { videoFrameWritten, stopThread });
        if (signalled == 0 && e.BytesRecorded > 0)
        {
            // Overloads with Span parameters are available on .NET 5+
#if NET5_0_OR_GREATER
            audioStream.WriteBlock(e.Buffer.AsSpan(0, e.BytesRecorded));
#else
                audioStream.WriteBlock(e.Buffer, 0, e.BytesRecorded);
#endif
            audioBlockWritten.Set();
        }
    }
}