嘿，我正在尝试找到将我的网络摄像头上的视频源更改为“复合”的设置。似乎如果我拔掉 USB 然后重新插入并启动代码，它就会出现一个空白屏幕。但是，一旦我更改视频源（在另一个程序中），然后返回并再次运行我的代码，它就会出现。
因此，我需要一些可以让我改变这一点的东西，以便在我自己的应用程序中发生同样的事情，而不必启动另一个具有该功能来设置网络摄像头的程序。
当我拔出 USB 电缆然后将其放回并运行源代码时，应用程序的图片框是黑色的。
The "other program" i use to change the video source (that seems to work to bring up the image):
After i use that "other program" i go back to the source code and run it and this is what i get then:
我正在使用此处名为 dot Net Webcam Library 的 C# 代码：在此输入链接描述
似乎使用了DirectShow在此输入链接描述
我在源代码中注意到它列出了不同类型的视频设置（在下面的 AXExtend.cs 中找到）：
public enum PhysicalConnectorType
{
Video_Tuner = 1,
Video_Composite,
Video_SVideo,
Video_RGB,
Video_YRYBY,
Video_SerialDigital,
Video_ParallelDigital,
Video_SCSI,
Video_AUX,
Video_1394,
Video_USB,
Video_VideoDecoder,
Video_VideoEncoder,
Video_SCART,
Video_Black,
Audio_Tuner = 0x1000,
Audio_Line,
Audio_Mic,
Audio_AESDigital,
Audio_SPDIFDigital,
Audio_SCSI,
Audio_AUX,
Audio_1394,
Audio_USB,
Audio_AudioDecoder,
}
但我不确定如何在代码中调用它：
Device selectedDevice = device as Device;
imageCapture.Device = selectedDevice as Device;
imageCapture.PerformAutoScale();
imageCapture.Refresh();
imageCapture.Start();
所以我猜测“Video_Composite”是我可能需要的才能做到这一点？
任何帮助都会很棒！谢谢！
David
代码更新
foreach (Device device in Device.FindDevices())
{
if (device.ToString() == "BackupCamera")
{
Device selectedDevice = device as Device;
IGraphBuilder graphBuilder = new FilterGraph() as IGraphBuilder;
DsDevice device1 = DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDevice)[1]; // <<--- Your Device
Guid baseFilterIdentifier = typeof(IBaseFilter).GUID;
object videoSourceObject;
device1.Mon.BindToObject(null, null, ref baseFilterIdentifier, out videoSourceObject);
IBaseFilter videoSourceBaseFilter = videoSourceObject as IBaseFilter;
graphBuilder.AddFilter(videoSourceBaseFilter, "Source");
ICaptureGraphBuilder2 captureGraphBuilder = new CaptureGraphBuilder2() as ICaptureGraphBuilder2;
captureGraphBuilder.SetFiltergraph(graphBuilder);
object crossbarObject;
captureGraphBuilder.FindInterface(FindDirection.UpstreamOnly, null, videoSourceBaseFilter, typeof(IAMCrossbar).GUID, out crossbarObject);
IAMCrossbar crossbar = crossbarObject as IAMCrossbar;
int inputPinCount, outputPinCount;
crossbar.get_PinCounts(out inputPinCount, out outputPinCount); // <<-- In/Out Pins
// Pin Selection: Physical Input 2 (e.g. Composite) to Capture Pin 0
crossbar.Route(0, 2);
imageCapture.Device = selectedDevice as Device;
imageCapture.PerformAutoScale();
imageCapture.Refresh();
imageCapture.Start();
}
}
在运行filer graph之前，您需要获取crossbar接口。您通常使用ICaptureGraphBuilder2::FindInterface为了这。这需要一个额外的过滤器和FindInterface由于这个原因，方法特别有用：
支持过滤器。如果捕获设备使用 Windows 驱动程序模型 (WDM) 驱动程序，则图表可能需要 WDM 视频捕获筛选器上游的某些筛选器，例如电视调谐器筛选器或模拟视频交叉开关筛选器。如果pCategory参数不等于NULL，该方法自动将任何所需的 WDM 滤波器插入图中.
完成此操作后，您将拥有IAMCrossbar接口，以及IAMCrossbar::Routemethod 是你如何切换输入。
也可以看看：交叉开关滤波器将当前输入更改为复合
代码片段：
IGraphBuilder graphBuilder = new FilterGraph() as IGraphBuilder;
DsDevice device = DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDevice)[1]; // <<--- Your Device
Guid baseFilterIdentifier = typeof(IBaseFilter).GUID;
object videoSourceObject;
device.Mon.BindToObject(null, null, ref baseFilterIdentifier, out videoSourceObject);
IBaseFilter videoSourceBaseFilter = videoSourceObject as IBaseFilter;
graphBuilder.AddFilter(videoSourceBaseFilter, "Source");
ICaptureGraphBuilder2 captureGraphBuilder = new CaptureGraphBuilder2() as ICaptureGraphBuilder2;
captureGraphBuilder.SetFiltergraph(graphBuilder);
object crossbarObject;
captureGraphBuilder.FindInterface(FindDirection.UpstreamOnly, null, videoSourceBaseFilter, typeof(IAMCrossbar).GUID, out crossbarObject);
IAMCrossbar crossbar = crossbarObject as IAMCrossbar;
int inputPinCount, outputPinCount;
crossbar.get_PinCounts(out inputPinCount, out outputPinCount); // <<-- In/Out Pins
// Pin Selection: Physical Input 2 (e.g. Composite) to Capture Pin 0
crossbar.Route(0, 2);