mavis webcam code

Your best bet is to contact Robin herself. She can probably tell you who is using it. She also wrote a multi-part article for SERVO magazine you'll want to find as well.

She wrote the DLL in C++, but you can use any programming language that can interface to a standard Win32 flat DLL. That's the benefit of a Windows DLL; it doesn't matter what language the person used to code it. You do not need C, unless that's the language of choice for you. VB6 or VB5 could just as easily use those DLLs.

-- Gordon

JGCASEY wrote:

Yes I have just sent Robin an email for suggestions but don't know what sort of reply she has time to give.

Deciding on a language has always been something of problem for me. I really only know standard Basic and C. Recently I have been playing with c#.net 2005. In true M$ tradition it is incompatible with everything before it including the c#.net 2003 sources I found on the net!! And that includes the source code for the WiMo robot project you made reference to in a recent post, subject RobotRealm. I have rejected the RobotRealm software at this stage. I don't really like its proprietary rights. Ideal software I think would be C++ with Linux/Windows compatible libraries for things like webcams. Java comes close but I didn't like that language much, too stuck with the old way of programming I guess.

I did play around with a webcam and vb5 many moons ago. My interest in all this tends to wax and wane, mainly wane :) Did a bit of image segmentation based on color but the grabs were too slow for a real time vision system.

The problem is getting a programming language that is fast enough and has the tutorials to explain, by stepping through examples, how to do things like using a dll for hobby programmers like me with limited spare time.

The problem is spending the least amount of time learning what I don't need to know in order to work out what I do need to know.

The leaf project is closer to what I would like to end up building but with a robust body so that if I ever reached old age I would have something to tend my needs :)

-- John

I doubt this. While there are some modifications to the framework, there are no synantical changes, so if your free version of 2005 doesn't open a 2003 project it's probably because it's the free version. MS has to make money somehow, and while they are giving away the 2005 Express versions of their compilers, the full feature set of the IDE is reserved for people who fork out the cash. This is a sad part of life.

My experience is that all my .NET 2003 projects open and run without with virtually no hiccups in 2005 (some minor changes because if anything MS got stricter with some coding styles), and I have some extremely complex apps with tens of thousands of lines of code.

I know you've said this before but frankly, what else can you expect. Your experience is with old, outdated software for which you'll be lucky to find examples for.

But as I said, any Windows programming platform that can call a standard DLL can interface to the Mavis library. A Microsoft Word macro could even do this.

-- Gordon

You can ask the Leaf group; their home page is at

Robin uses C++.

The non-visual Microsoft compiler is free for for download. Unfortunately I have no idea how to use it.

I assume you are a Java man? I did begin to learn Java a few years back so I guess I know 90% of the basics of Java programming. I didn't think Java would be fast enough for vision?

I did think about returning to Java after visiting the generation5 site which seems to have died:

It also had interesting articles on vision problem by Bob Mottram.

Perhaps I should start revising my knowledge on java and finish learning what I started. Have you used the Java Media Framework API?

-- John

It depends on the platform. Java can be fast enough for some types of vision. I've been thinking of rewriting MAVIS in Java just so I can understand it.

There code is still fairly good.

I've used it a bit. Unfortunately I don't remember enough about it right at the moment because I've been away at other projects.

Can you rewrite framecap as that is the heart of the code.

Framecap is written in vc++ and has to be running "as a server" to be used as a dll in other code. I compiled the fgDllUser source code with the Dev-cpp IDE and it worked but I don't understand why framecap has to be running first.

-- JC

-- JC

Framecap is merely something that captures images for MAVIS to deal with. MAVIS doesn't deal directly with the cameras.

This is purely my understanding. I have yet to mess with the code more than trivially.

Yes I understand it now. The fgClient.dll is just an interface to framcap which has to be running before you start your own program running. Seems silly to me. An ideal situation would be to do what I did with my old DOS cam. Just put all the capture stuff etc in a header file so you can use image = GrabImage().

-- JC

Hey John.

There are 3 main advantages to having Framecap running as a separate server:

1) you could actually have multple programs running simultaneously that would grab images from the server. 2) Since it's a separate program, you could muck around with other code all you want without screwing up the Framecap code - thus being assured that it is working by checking it with another program that uses the dll --- a big advantage during debugging ! 3) By having access to Framecap being through a DLL, you only need to link in a smaller portion of code to get your images, thus keeping your final executable smaller than if you linked the entire code in with each program you wrote. This is really only an advantage if you have several different programs that you want to do frame capture in. Otherwise, it makes just as much sense, as you noted, to just link it via a header file.

Hope that helps a little bit ! JCDeen

Robin Hewitt the author of mavis was kind enough to explain her reasoning behind the software and I don't think she would mind me duplicating it.

===

One reason for writing framecap as a server application was to view live video feed without having to write a custom application to do that. Another reason was to provide an interface for accessing the camera driver through an OLE interface without having to stop and restart the video feed. A third reason was to provide support for distributed processing. Computer vision is computationally demanding, and it's common to process data from a single source on multiple machines.

===

I may still use it with gcc or vc++.net once I get the tutorials to get me up to speed.

I have a renewed interest in the subject, an interest that waxes and wanes continually, mostly wanes :) as someone has shown me another take on visual processing.

-- JC