[Kdenlive-devel] Kdenlive now handles <setSceneList>

[Jason Wood]

On Sunday 01 Dec 2002 12:11 pm, Rolf Dubitzky wrote:
> On Saturday 30 November 2002 11:30 pm, Jason Wood wrote:
> > There are a couple of minor points I think you should know about :
> >
> > * Occasionally Kdenlive will generate a tiny scene (with a duration of
> > something like 1e-14). I'm not sure if they will cause a problem or not.
>
> Why is that?

Rounding errors - I am doing a simple comparison of if timeA <  timeB or not, 
and sometimes it is but shouldn't be :-) I'm exploring the best way to fix 
this.

> > * At the moment, If there are no clips for a part of the timeline,
> > Kdenlive generates an empty scene. I.e.
> >
> > <scene duration="12.45" />
>
> That's fine. At present piave does not allow empty frames, i.e. frames
> where no information and all other inconsistencies. PIAVE fixes all such
> errors/inconsistencies, but this is actually a 'feature' that can be
> switched off.

Ok.

> > Piave should display black in these situations, I think ;-)
>
> MovieDVperfect displays a test screen. This way you'll notice directly if
> you have such errors/inconsistencies in your timeline.  It's trivial to
> implement a command to let the user choose what happens with empty frames
> (black, white, testscreen, etc.)

I think in most cases, people will expect an empty timeline to generate a 
black video, but I can see cases where having a video equivalent of 
0xDEADBEEF would be very useful. See below.

> > We need to
> > discuss the best way to handle this and overlaying one image onto another
> > as well - I think that this needs to be standardised somewhat.
>
> What do you mean with overlaying? One problem I see is, when you have two
> clips on top of each other in the timeline and you have not defined an
> operation between the two. In this case piave uses a NullOp which will just
> pass through the fame from he first (top) track. Is this what you are
> referring to?

That behaviour is fine for Piave, in which case the task of setting up 
overlays will be left on the GUI side.

By overlaying, I am talking about the task of placing one video on top of 
another, as would be done when performing alpha-blend, pic in pic, or any 
other transition-type effect that you can think of :-)

One very large feature that I would like to see (I don't think it would be 
hard to implement, but I do think it would be hard to implement efficiently) 
is the ability to use the GIMP-style layer modes. For instance, Normal, 
screen, addition, subtraction, lightest, darkest, hue, saturation, etc. when 
overlaying one clip on another.

But to be back on topic of when I was talking about 0xDEADBEEF - as soon as we 
start messing around with alpha channels, performing blue screen effects and 
the like, it would be useful if there was a way to tell that we have 
"covered" the entire picture or not with video. I think a test screen that 
would effectively be the bottom-most layer of every scene would be useful for 
this purpose.

Cheers,
Jason

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