[Kdenlive-devel] Scripting

[Jason Wood]

On Thursday 25 March 2004 21:43, Rolf Dubitzky wrote:
> On Friday 26 March 2004 02:28, Rolf Dubitzky wrote:
> > On Thursday 25 March 2004 19:34, Jason Wood wrote:
> > > Hi,
> > >
> > > I want to throw a thought at the mailing list and see what bounces back
> > >
> > > :-)
> > >
> > > With the latest versions of QT and KDE, it is very easy to make an
> > > application scriptable. I am starting to contemplate adding this
> > > ability to Kdenlive.
> >
> >     I agree with Dan here. In principle I think when it comes to
> > scripting features kdenlive is the wrong place to implement them. This
> > should be done in piave.
> >     I agree that KDE/Qt provides very powerfull scripting features and
> > DCOP is _really_ easy and powerfull. My problem is that the KDE guys keep
> > it KDE/Qt specific. That is really a pitty. Same goes for the IOslaves.
> > Very powerfull and easy, yet, completely stupid to implement this on a
> > desktop level.

To get things clear, I am not talking about DCOP scripting here, I am talking 
about QSA - Qt Script for Applications, (and there is a similar KDE-specific 
version that I believe allows you to use alternative scripting langauges to 
QScript.)

http://doc.trolltech.com/qsa-1.1/index.html

> > All these features should be developed on OS level. 
> >     As far as you examples go choose emacs/shell/perl/python/ruby/tcl and
> > generate VEML. send this to piave. genereating and parsing XML like
> > syntax is usually very easy from perl/python/ruby/tcl. It really sounds
> > odd to me to uses some scripting functionality of a GUI library to
> > controll a GUI which in turn controlls an engine via scrips.

The analogy here is : is it better to use, say, Image Magick to perform image 
manipulations, or is it better to use a script from within gimp? The answer 
is : it depends on what you are doing.

If you want to apply a script to a particular part of an image that you are 
interested in, then it is easier to select the area using gimp's selection 
tools than it would be to manually construct the script required to pass into 
some image filtering software.

Conversely, If you are batch-converting a number of files from one format to 
another, then going through a gui is painfully slow compared to writing a 
script to do it using image magick.

Returning to Kdenlive/piave the same issue applies. If you want to manipulate 
VEML to get the desired effect, then there is nothing stopping you, and it 
would be useful if there is functionality in piave that cannot be easily 
accessed using the Kdenlive interface. 

On the other hand, if you want the manipulations you perform to affect your 
Kdenlive project file, perhaps manipulating those bits of information that 
don't exist in VEML - then it makes sense to manipulate it at the Kdenlive 
level.

The two ways of scripting are not mutually exclusive. Manipulating VEML by 
script is presumably already possible. With the Qt MOC, the type of scripting 
that I am talking about is possible with little work.

> > The only thing I can see where this might be usefull is when it really
> > comes to GUI stuff. I.e. when you want to integrate kdenlive in a DVD
> > author. But then again, I think it make more sense to do it the other way
> > round and integrate the DVD authoring software in kdenlive. Well, I
> > suppose you can do it either (and both) ways.

This kind of scripting would be more likely to let you integrate DVD authoring 
into kdenlive than the other way around.

Cheers,
Jason

-- 
Jason Wood
Homepage : www.uchian.pwp.blueyonder.co.uk