Develop Reference

How to forward output of a directshow app(C++) to a C# app?

I am making a C# app to capture graphic from an avermedia pcie capture card.
But it seems that there are no out of box tools to do so.
So I made a C++ directshow app to do the capture, which is a console app and opens a capture window when running.
How can I redirect the output to a C# app? for example, to a CaptureElement?

So you want to have XAML CaptureElement connected to AverMedia PCIe capture card. This sounds like a well-understood challenge overall, however every other piece of technology you mentioned is eventually a bad choice: DirectShow, multiple apps with piping, redirection and fitting of cutsom code to XAML CaptureElement control.
Microsoft has intentionally been limited ways you can integrate different APIs and so there are not so many ways to get everything together.
Let us go over the supposed integration path. The capture card is supposed to be shipped with a compatible driver:
Video capture devices are supported through the UVC class driver and must be compatible with UVC 1.1
When this is the case, such devices are visible to Media Foundation API handling video capture among tasks. XAML CaptureElement would be able to see a video capture device through this API and this way everything is supposed to work without need to fit anything from your end.
If this is not happening, it suggests you are dealing with an unsupported device coming without suitable or compatible driver.
Previous media API in Windows was DirectShow but its days are gone. It remains perfectly working as a legacy framework, a lot of applications out there are still relying on it. Specifically it will not integrate with new technology like XAML and UWP. More to that, even Media Foundation itself, the current media API, in its public offering is lagging behind when it comes to fitting with most recent technology. Having said that it is a good idea to stay well clear of DirectShow here if this is at all possible.
I see no need for cross-process design with video travelling between process through piping. There is no good reason for such design and even though this can work efficiently (Windows itself proves it can work great in terms of performance by having so called Frame Server service in it), this is not to be built on piping. In your case it is unlikely to be have to be built on multiple processes either. Instead you can develop a native code DLL project that takes care of video acquisition and connects to managed code via suitable glue layer: C++/CLI, COM, C++/WinRT and such.
Then next thing is fitting to XAML CaptureElement. The control is designed to work with Windows.Media.Capture.MediaCapture class that talks to hardware and you don't have suitable hardware as you plan to implement your own acquisition layer. Long story short you are not supposed to forward external data to CaptureElement and you would have hard time doing this. Your best strategy is to upload externally obtained data to Windows.Graphics.Imaging.SoftwareBitmap or alike and take involved performance impact as acceptable. That is, you will be dealing with video frames as images.
An alternative way is to upload acquired video frames into Direct 3D 11 textures and it would open you a more performant way of integration with video related controls, such as Windows.UI.Xaml.Controls.SwapChainPanel however it would also require that you put much more development effort in there.

Camera Capture with External Camera with C#

I have a Nikon D90 connected to my laptop via USB. I need to be able to simply trigger the camera to capture an image via C#.
This seems like it should be an easy problem but I have been drowning trying to figure it out...
Can anyone point me in the right direction?

You would need Nikon's SDK to accomplish that. What you're after is a remote control function for your camera. Nikon is offering their SDK for free but there's a lengthy T&C, a learning curve and a hunt for the C# wrapper so it's not a trivial task.

Localization of a robot using Kinect and EMGU(OpenCV wrapper)

I'm working on small WPF desktop app to track a robot. I have a Kinect for Windows on my desk and I was able to do the basic features and run the Depth camera stream and the RGB camera stream.
What I need is to track a robot on the floor but I have no idea where to start. I found out that I should use EMGU (OpenCV wrapper)
What I want to do is track a robot and find it's location using the depth camera. Basically, it's for localization of the robot using Stereo Triangulation. Then using TCP and Wifi to send the robot some commands to move him from one place to an other using both the RGB and Depth camera. The RGB camera will also be used to map the object in the area so that the robot can take the best path and avoid the objects.
The problem is that I have never worked with Computer Vision before and it's actually my first, I'm not stuck to a deadline and I'm more than willing to learn all the related stuff to finish this project.
I'm looking for details, explanation, hints, links or tutorials to achieve my need.
Thanks.

Robot localization is a very tricky problem and I myself have been struggling for months now, I can tell you what I have achieved But you have a number of options:
Optical Flow Based Odometery: (Also known as visual odometry):
Extract keypoints from one image or features (I used Shi-Tomashi, or cvGoodFeaturesToTrack)
Do the same for a consecutive image
Match these features (I used Lucas-Kanade)
Extract depth information from Kinect
Calculate transformation between two 3D point clouds.
What the above algorithm is doing is it is trying to estimate the camera motion between two frames, which will tell you the position of the robot.
Monte Carlo Localization: This is rather simpler, but you should also use wheel odometery with it.
Check this paper out for a c# based approach.
The method above uses probabalistic models to determine the robot's location.
The sad part is even though libraries exist in C++ to do what you need very easily, wrapping them for C# is a herculean task. If you however can code a wrapper, then 90% of your work is done, the key libraries to use are PCL and MRPT.
The last option (Which by far is the easiest, but the most inaccurate) is to use KinectFusion built in to the Kinect SDK 1.7. But my experiences with it for robot localization have been very bad.
You must read Slam for Dummies, it will make things about Monte Carlo Localization very clear.
The hard reality is, that this is very tricky and you will most probably end up doing it yourself. I hope you dive into this vast topic, and would learn awesome stuff.
For further information, or wrappers that I have written. Just comment below... :-)
Best

Not sure if is would help you or not...but I put together a Python module that might help.
http://letsmakerobots.com/node/38883#comments

Record video from camcorder in C#

I need to be able to record video from an external camera in a C# application.
Unfortunately a webcam is pretty much out of the question as the application will record outside and during the evening/night. That is why I was thinking of a camcorder since it also has manual control over exposure and focus, lower noise and better sensor.
So far I would use the AV/S-Video output from the camcorder and send the signal to a USB capture card (the computer is a laptop so no PCI-E cards).
How would I be able to access the video stream from the C# application, now that it comes from the capture card ?
Does my proposed system seem feasible (achievable, good video quality, good fps)? Does anybody have another working solution?
Thanks

This Code Project Article could be of a good starting point.
The Author mentions :
The main goal of the application was to make it flexible and
extensible. The application itself can communicate with any video
source – it may be an IP video camera or a server, it may be a local
camera attached to USB, it may be an MMS stream from a remote server,
or it may be any other video source. And more of it, the application
can work with all these video sources simultaneously, displaying them
all on a single screen.

The solution I used in the end was Microsoft Expression Encoder.

Expose my program to other programs

I'm messing with the idea of writing a small program to mirror output of a video capture device. If you buy a video capture device you can only use it with one program at a time because the device gets locked. Instead of buying a second capture card id like to write a program to accept input from my capture device and expose the output to other applications.
Capture Device----->Program---->Flash Media Encoder
I've never done this type of thing before. Is it device driver related? Can I make my program look like a capture device to other programs without digging in device driver dev?
If someone could point me in the right direction that would be great.

Can I make my program look like a capture device to other programs without digging in device driver dev?
-No, I'm afraid not. You'd need to do exactly that, write a driver or capture source of your own. You could make some interface to serve up image to multiple apps (what a great idea!) but then it would need to be standardised, and you'd need other companies or developers to use that interface. Again a great idea but you'd need to agree on the feature set - and each developer would likely want something new or different.
(If you are talking about particular/specific other programs, they might have a particular interface you can work with already..)
(I was also assuming you were talking about realtime video capture: if you're talking about photo capture etc, you could write an image file to disk, and then import into the other apps ... not as joined up or integrated as ideal though)
Hope that helps - not an ideal situation though!

I will not say it is impossible, but I will say it is impossible in C# because this will require you to write a device driver software which can emulate virtual capture devices which your other program can use and your program can capture actual capture device and mirror or split the data to virtual capture devices that your device driver will create.
Very much same to Virtual CD Rom Drives that we can create with some software, you will need windows device driver kit for that.
You can write combination of application, one device driver and you can have some sort of C# api or program to control the operation.