C#屏幕录制中遇到黑屏问题的原因和解决方法

// ❌ 错误：屏幕录制成了"黑盒"，无状态、无错误处理
using WMEncLib; // 引用Windows Media Encoder

public class ScreenRecorder
{
    private WMEncoder _encoder;
    
    public void StartRecording(string outputFilePath)
    {
        _encoder = new WMEncoder();
        _encoder.AddVideoInputMedia(new WMVidSource(), 0, 0); // 没有检查输入源
        _encoder.AddOutputFile(outputFilePath, out IWMProfile profile, out IWMOutputMediaProps outProps);
        _encoder.Start();
    }
    
    public void StopRecording()
    {
        _encoder.Stop();
    }
}

// ✅ 正确：屏幕录制绑定资源管理，有血有肉
public interface IScreenRecorder
{
    void StartRecording(string outputFilePath);
    void StopRecording();
}

public class ScreenRecorder : IScreenRecorder, IDisposable
{
    private WMEncoder _encoder;
    private bool _isRecording;
    
    public ScreenRecorder()
    {
        // 1. 初始化时检查依赖
        if (!IsWindowsMediaEncoderInstalled())
            throw new InvalidOperationException("Windows Media Encoder 未安装");
    }

    public void StartRecording(string outputFilePath)
    {
        // 1. 检查是否已在录制
        if (_isRecording)
            throw new InvalidOperationException("已处于录制状态");
            
        // 2. 创建编码器实例
        _encoder = new WMEncoder();
        
        // 3. 配置输入源（屏幕捕获）
        var inputProps = _encoder.AddVideoInputMedia(new WMVidSource(), 0, 0);
        if (inputProps == null)
            throw new Exception("无法添加视频输入源");
            
        // 4. 配置输出文件
        IWMProfile profile;
        IWMOutputMediaProps outProps;
        var outputProps = _encoder.AddOutputFile(outputFilePath, out profile, out outProps);
        if (outputProps == null)
            throw new Exception("无法添加输出文件");
            
        // 5. 启动录制
        _encoder.Start();
        _isRecording = true;
    }

    public void StopRecording()
    {
        if (!_isRecording)
            throw new InvalidOperationException("当前未处于录制状态");
            
        _encoder.Stop();
        _isRecording = false;
        _encoder.Dispose(); // 释放资源，避免内存泄漏
    }

    public void Dispose()
    {
        if (_encoder != null)
        {
            _encoder.Dispose();
            _encoder = null;
        }
    }

    private bool IsWindowsMediaEncoderInstalled()
    {
        // 检查Windows Media Encoder是否安装
        try
        {
            var encoder = new WMEncoder();
            return true;
        }
        catch
        {
            return false;
        }
    }
}

// ❌ 错误：C#屏幕录制，性能差，无错误处理
public class BadScreenRecorder
{
    public void RecordScreen(string outputPath)
    {
        // 1. 用System.Drawing捕获屏幕，每帧都存
        for (int i = 0; i < 30; i++)
        {
            var bitmap = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height);
            using (var g = Graphics.FromImage(bitmap))
            {
                g.CopyFromScreen(0, 0, 0, 0, Screen.PrimaryScreen.Bounds.Size);
            }
            bitmap.Save($"frame{i}.bmp");
        }
        
        // 2. 无编码，直接存BMP，文件巨大
    }
}

// ✅ 正确：C#屏幕录制，性能优，有错误处理
public class GoodScreenRecorder : IScreenRecorder, IDisposable
{
    private WMEncoder _encoder;
    private bool _isRecording;
    private readonly int _frameRate;
    
    public GoodScreenRecorder(int frameRate = 30)
    {
        _frameRate = frameRate;
        if (!IsWindowsMediaEncoderInstalled())
            throw new InvalidOperationException("Windows Media Encoder 未安装");
    }

    public void StartRecording(string outputFilePath)
    {
        if (_isRecording)
            throw new InvalidOperationException("已处于录制状态");
            
        _encoder = new WMEncoder();
        
        // 1. 配置输入源（屏幕捕获）
        var inputProps = _encoder.AddVideoInputMedia(new WMVidSource(), 0, 0);
        if (inputProps == null)
            throw new Exception("无法添加视频输入源");
            
        // 2. 配置输出文件（WMV格式，压缩）
        IWMProfile profile;
        IWMOutputMediaProps outProps;
        var outputProps = _encoder.AddOutputFile(outputFilePath, out profile, out outProps);
        if (outputProps == null)
            throw new Exception("无法添加输出文件");
            
        // 3. 配置编码参数（性能优化）
        _encoder.SetVideoBitrate(1000000); // 1Mbps
        _encoder.SetFrameRate(_frameRate);
        
        _encoder.Start();
        _isRecording = true;
    }

    public void StopRecording()
    {
        if (!_isRecording)
            throw new InvalidOperationException("当前未处于录制状态");
            
        _encoder.Stop();
        _isRecording = false;
        _encoder.Dispose();
    }

    public void Dispose()
    {
        if (_encoder != null)
        {
            _encoder.Dispose();
            _encoder = null;
        }
    }
}