[Kdenlive-devel] The Next Big Thing

[Jason Wood]

On Wednesday 08 Jan 2003 5:09 pm, Rolf Dubitzky wrote:
> What does the <requirements> tag do? I don't understand it and it looks
> redundant.

At the moment, it is. But the <getCapabilities/> command is asking for 
_everything_ that the renderer is capable of, not just effects. Later on, it 
might be extended to look like this :

<requirements>
	<general>
		<!- General render capabilities defined here, such as a maximum project 	
		length (if any), does it need each clip to start/end on a frame boundary, is 
		the renderer capable of a "preview" mode, etc. -->
	</general>
	<format>
		<!-- file formats defined here -->
	</format>
	<effects>
		<!-- Effects defined here -->
	</effects>
<requirements/>

and so on. The only reason that I have made these one command, is that I don't 
think it matters if they are seperated out - essentially, I oinly expect this 
command to be called once on initialisation of the renderer. If we split 
effects, file formats, etc. into seperate commands, we would just call each 
individually.

Saying that, I don't think <requirements> is a good word - perhaps 
<capabilities> makes more sense.

>
> In <input type"video"/> , what is "video" supposed to mean? If this in
> contranst to "audio"? If yes, then the crossfade should be "av"

Ok, at some point I am expecting that we will have both video and audio 
effects seperately, but "av" would be correct if the effect manipulates both.

> I guess < ... type="linear"> is meant to describe the interpolation. I
> think this should be an atribute to the <parameter> tag and it should be
> named "interpolation".

The type="linear" is defining how the interpolation works for that keyframe 
only. It might make sense to say which keyframee types are supported by the 
renderer  (e.g. step, linear, bezier), but at the moment, I am assuming 
"linear" only, so that is not too important.

The idea is though, that you can say something along the lines of :

"From 0 to 10, linearly interpolate from values 0.0 to 1.0, and then use 
bezier interpolation to reach 20 at value 0.5. Then, on reaching 30, step to 
1.0 (i.e., 'jump' from one value to the other"

I am unsure as to what values will be needed to support the various types of 
interpolation that we might have, but I hope you get the general idea of what 
I am talking about.

Cheers,
Jason

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