Are these parameters??

There are some weird lines of code in this .cpp file

Code:

VideoInput::VideoInput(): 
    capture(cvCaptureFromCAM(0)), framecount(0),
	frame(cvQueryFrame(capture)), size(cvSize(frame->width, frame->height))
{}

VideoInput::VideoInput(const char* filename):
    capture(cvCaptureFromFile(filename)), framecount(0),
    frame(cvQueryFrame(capture)), size(cvSize(frame->width, frame->height)) 
{}

What exactly is:

capture(cvCaptureFromFile(filename)), framecount(0),
frame(cvQueryFrame(capture)), size(cvSize(frame->width, frame->height))

It's not parameters? They're just function calls stringed together via comma's....

No, they're part of a constructor initialisation lists. I.e. those are constructor calls for some of its members.

I think part of why it's confusing is the way it's written too. I would write it like this:

Code:

VideoInput::VideoInput()
:
    capture(cvCaptureFromCAM(0)),
    framecount(0),
    frame(cvQueryFrame(capture)),
    size(cvSize(frame->width, frame->height))
{
}

VideoInput::VideoInput(const char* filename)
:
    capture(cvCaptureFromFile(filename)),
    framecount(0),
    frame(cvQueryFrame(capture)),
    size(cvSize(frame->width, frame->height)) 
{
}

In particular I think it's good for that ':' to appear on its own line to emphasise that this is an unusual block of code. Written like that even a newbie should be able to see that ':' and think "oh, well this is just a structure I haven't seen before". If the ':' is on the end of the line above it can be easily missed and you see the unusual nature of the code below and you have to backtrack to see the ':' to confirm that it's an initialisation list.