如何在Golang中的差异函数中杀死命令Exec

我正在使用命令exec运行FFMPEG制作基于web的屏幕记录.在这里，我创建了一个startRecording函数，但我仍然对在stopRecording函数中停止命令进程感到困惑，因为命令是在startRecording函数中执行的.如何在stopRecording函数中停止已在srartRecording函数中运行的进程？

这是我的代码

//Handler to create room/start record
func RoomCreate(c *fiber.Ctx) error {
    fileName := "out.mp4"
    fmt.Println(fileName)
    if len(os.Args) > 1 {
        fileName = os.Args[1]
    }

    

    errCh := make(chan error, 2)
    ctx, cancelFn := context.WithCancel(context.Background())
    // Call to function startRecording
    go func() { errCh <- startRecording(ctx, fileName) }()

    go func() {
        errCh <- nil
    }()
    err := <-errCh
    cancelFn()
    if err != nil && err != context.Canceled {
        log.Fatalf("Execution failed: %v", err)
    }
    
    return c.Redirect(fmt.Sprintf("/room/%s", guuid.New().String()))
}



//Function to run command FFMPEG
func startRecording(ctx context.Context, fileName string) error {
    ctx, cancelFn := context.WithCancel(ctx)
    defer cancelFn()
    // Build ffmpeg
    ffmpeg := exec.Command("ffmpeg",
        "-f", "gdigrab",
        "-framerate", "30",
        "-i", "desktop",
        "-f", "mp4",
        fileName,
    )
    // Stdin for sending data
    stdin, err := ffmpeg.StdinPipe()
    if err != nil {
        return err
    }
    //var buf bytes.Buffer
    defer stdin.Close()
    // Run it in the background
    errCh := make(chan error, 1)

    go func() {
        fmt.Printf("Executing: %v\n", strings.Join(ffmpeg.Args, " "))
        
        if err := ffmpeg.Run(); err != nil {
            return
        }
        //fmt.Printf("FFMPEG output:\n%v\n", string(out))
        errCh <- err
    }()
    // Just start sending a bunch of frames
    for {
        
        // Check if we're done, otherwise go again
        select {
        case <-ctx.Done():
            return ctx.Err()
        case err := <-errCh:
            return err
        default:
        }
    }
}

//Here function to stop Recording
func stopRecording(ctx context.Context) error {
//Code stop recording in here
} 

谢谢你的预付款