Take a look at cvSmooth docs. You can see that it has a type parameter, followed by param1, param2, param3 and param4 that have different semantics if different type is used. The question is how to expose those in the 'cvsmooth' GstElement?
I could think of 3 different choices here:
1) Go straightforward and use the same API as OpenCV
As a result, we should have an element with the properties named after the OpenCV parameters:
"cvsmooth type=blur param1=5 param2=3 param3=0.0 param4=0.0"
This results in a very not intuitive API, but we keep it aligned with OpenCV's, making it easy to people that already know one API to use the other one. The element docs would mostly point to OpenCV's docs. Resulting code is simple and easy to maintain.
2) Have multiple elements: cvsmoothblur, cvsmoothgaussian, cvsmooth...
We could have each smooth algorithm (type) into a separate element and have its properties reflect the semantics of this type. For example, we would have cvsmoothblur, cvsmoothmedian and one for each type. The properties of each one would named accordingly to its semantics, instead of some paramX.
This provides a nice API but might increase the number of elements for every function that has this type or a similar parameter. I don't know how common this is. This might be a good solution if there are a few of those. A downside is that switching the type has to use hot-swapping but I don't think this is a common use case.
3) Expose properties for each semantics and use them only if their type is selected.
We still keep it to one element, but we add one property for each semantic a parameter can assume. Those would only be used it we have its corresponding type is selected.
For example: param3 might be the "gaussian standard deviation" or the "color sigma" if type is gaussian or bilateral respectively. We add those 2 properties (standard-deviation and color-sigma) that are only going to be used if their types are selected.
This makes those lines possible:
"cvsmooth type=gaussian standard-deviation=5.0" or
"cvsmooth type=bilateral color-sigma=1.0"
Code is a little messier than options above.
Given those options, I really don't like option 3. I'm considering 1 or 2. From a quick look at some pages of OpenCV's transformations API I could see that this is not very common, and when it happens, only one parameter has a 'variable semantic', looks like I picked the trickiest one as my example.
So, which option would you chose?