尝试从网络摄像头预览视频时出现性能问题

Question

我编写了一个小应用程序，它仅显示网络摄像头或捕获卡的预览。目前，它完全按照我想要的方式工作，除了采集卡显示的帧速率比我想要的低得多。

这是我的相关代码：

    private const int WM_CAP_DRIVER_CONNECT = 1034;
    private const int WM_CAP_SET_PREVIEW = 1074;
    private const int WM_CAP_SET_PREVIEWRATE = 1076;
    private const int WM_CAP_SET_SCALE = 1077;
    private const int WS_CHILD = 1073741824;
    private const int WS_VISIBLE = 268435456;
    private const short SWP_NOMOVE = 2;
    private const short SWP_NOZORDER = 4;
    private const short HWND_BOTTOM = 1;
    private const int iDevice = 0;
    private int hHwnd;
    private int previewRate = 34;
    private int width = 640;
    private int height = 480;

    [DllImport("user32.dll", EntryPoint="SendMessageA")]
    public static extern int SendMessage(int hWnd, uint Msg, int wParam, int lParam);

    [DllImport("user32.dll", EntryPoint="SetWindowPos")]
    static extern int SetWindowPos(int hwnd, int hWndInsertAfter, int x, int y, int cx, int cy, int wFlags);

    [DllImport("user32.dll")]
    static extern bool DestroyWindow(int hndw);

    [DllImport("avicap32.dll")]
    public static extern int capCreateCaptureWindow(string lpszWindowName, int dwStyle, int X, int Y, int nWidth, int nHeight, int hwndParent, int nID);

    private void OpenPreviewWindow() 
    {
        hHwnd = capCreateCaptureWindow(iDevice.ToString(), (WS_VISIBLE | WS_CHILD), 0, 0, width, height, Handle.ToInt32(), 0);

        //  Connect to device
        if (SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, iDevice, 0) != -1) 
        {
            SendMessage(hHwnd, WM_CAP_SET_SCALE, 1, 0);
            SendMessage(hHwnd, WM_CAP_SET_PREVIEWRATE, previewRate, 0);
            SendMessage(hHwnd, WM_CAP_SET_PREVIEW, 1, 0);
            SetWindowPos(hHwnd, HWND_BOTTOM, 0, 0, width, height, (SWP_NOMOVE | SWP_NOZORDER));
        }
        else 
        {
            DestroyWindow(hHwnd);
        }
    }

当我在 FMLE 等应用程序中预览采集卡时，它以 30 FPS 预览，这是我的目标帧速率（每帧约 34 毫秒），但是当我使用我的应用程序预览时，它更接近 10- 15 帧/秒。我可能还应该注意到，我的程序将从我的网络摄像头预览 30 FPS。采集卡出现问题的原因是什么？如何修复？

Answer 1

使用 DirectShow 查看网络摄像头。

例如： http://www.codeproject.com/KB/audio- video/WebcamUsingDirectShowNET.aspx

或 http://www.codeproject.com/KB/miscctrl/webcam_c_sharp.aspx