Trying to Reference Stream Engine “Invalid or Unsupported”

[N A]

I’m trying to use the stream engine in a c# project on Visual Studio. When I try to add the dll as a reference manually I get an error saying “The reference is invalid or unsupported.” Before that I tried using NuGet to add it but it didn’t appear to do anything at all and then I was told I shouldn’t use the NuGet version because it was outdated.

I’ve never used Visual Studio or C# I’m totally lost. Following the steps that I find online like I was advised to on the Tobii discord has led me to a brick wall every time.

All I have so far is an exact copy of the c# sample listed on the Tobii site for stream engine but I can’t get past adding the stream engine to the project.

[Grant [Tobii]]

Hi @null, sorry to hear about your troubles. The Stream Engine API is designed for experienced users and comes with limited documentation.

As you are new to Visual Studio and C#, we would recommend that you instead try using our Interaction Library API which should provide you with all the data you require for your project. In addition, we have composed a details startup guide and getting started tutorial for C# bindings also which you can find @

Getting Started

Hopefully this should get you and running using eye tracking. Please go through our guide and let us know how you get on. Best Wishes.

[N A]

@grant-rogers If, if I’m correct in assuming that the stream engine sample provides all the more complicated elements that have to do with setup and cleanup of the stream engine then I think I can manage it. My “project” is nothing more than creating a dll that provides functions to get the most recent gaze data. Nothing more. Then I plan to use another unsupported language’s ability to make dll calls to work in a familiar environment that is also infinitely more convenient for my purposes. But to reiterate, the single purpose I have is functions that return the most recent data. That’s it. So if the sample on the website is all that’s needed to make it work, then I have an idea of what tweaks to make if I can only get the project set up correctly.

But really, I am doing nothing more than tweaking the sample.

[Grant [Tobii]]

Hi @null, okay thank you for the clarification, seems like you should be able to get up and running. Please bear in mind that if you are intending to store the gaze data (ie non-inertaction purposes) then you are legally required to purchase a Research or Commercial license for this purposes.

You can read more about this @ https://developer.tobii.com/license-agreement/

Please do let us know if you have any further questions. Best Wishes.

[N A]

Ok, but I still can’t add the library to the project. As far as I know, the stream engine dll is all I need to add, and everything I find says to add it in the way that results in the error I mentioned earlier. So, what am I missing?

[Grant [Tobii]]

As mentioned above, please try with the Interation Library API and its associated tutorials which explains in depth how to get started as the Stream Engine API is designed for advanced users. If you follow the correct procedures as outlined @ https://developer.tobii.com/consumer-eye-trackers-interaction-library-getting-started/ you should be able to obtain the results you need quickly.

[Hongbin Zou]

Hi N A,
If you’ve never used Visual Studio or C#, then even setting up a simple project can sometimes be quite troublesome. Learn the IDE first.
And if you want to make interop calls from some other languages, let’s say Python, to a C# dll, then bear in mind that this is not as easy as it seems to be, as C# dll normally do not have export functions. You have to use some 3rd party projects (e.g. DllExport) to accomplish this. And to use them correctly you really need to learn some C# first.
Or you can go the server-client way, sending data through sharedmemory or something. Still not easy, I think.
If I were you, I’d go for VS2019 and C++. Things might be quicker if you can use C++.

[Author]

Posts