[Kdenlive-devel] transitions

[Rolf Dubitzky]

On Tuesday 20 May 2003 11:25, Jason Wood wrote:
> In this scene, we have an effect that takes a single track as input. A
> video effect is applied called "textmaster", which presumably draws some
> text over the top of the video clip. The effect has two parameters - font
> and size. The font is defined to be spacetoa.ttf, and the size (of the
> font, or of the entire displayed text?) changes over time.

'size' is the size of the font. eventually this will become redundant with the
'height' and 'width' parameters. The idea is to specify a box on the screen 
which defines the text size(width/height). but that is not yet implemented

> A few questions :
>
> Do we need to specify the number of tracks in the <effect> tab? This could
> be determined easily as we parse the <inputs/> section of the effect.

In principle, yes. But this little redundancy is very helpfull at this point.

> I think this question is something that we haven't really discussed yet :
> what effects do we need, and how should they be implemented? I bring this
> up because, for example, it is possible that we would want to have text
> displayed on screen that is not attached to any underlying clip. In the
> interface, this could be shown by dragging a "text clip" onto the screen
> and filling out it's parameters.

That is trivial. The underlying 'media' (in piave terms) would be a 
ColorStill, where the color can be 100% transparent.

> Displaying text could be treated as a "generate text clip" operation,
> followed by an "overlay" operation, and the position of a clip could be
> modified by a generic "translation" operation, or it can be special-case.
>
> Have you had any thoughts on this?

Yes, I though this through a couple of times. All functionality is already 
there. We don't need a 'text clip'. Just take a ColorStill (transparent or 
not, the color (including alpha channel) can also be dynamic) and then apply 
a text-effect. You can e.g. 'overlay' this track onto a video track. Or Have 
a crossfade transition between them, whatever, everything you need for that 
already works with the current setup.

Cheers,
Rolf

***************************************************************
 Rolf Dubitzky          http://hep.phy.tu-dresden.de/~dubitzky
 e-mail:         Rolf.Dubitzky at Physik dot TU-Dresden dot de
***************************************************************