[Kdenlive-devel] % lost in keyframeable effects

[Dan Dennedy]

On Fri, Jul 3, 2009 at 2:17 AM, Marco<g.marco at freenet.de> wrote:
>> On Thursday 02 July 2009 18:50:39 Dan Dennedy wrote:
>>> On Thu, Jul 2, 2009 at 4:21 AM, Marco<g.marco at freenet.de> wrote:
>>> > Easy to see in the vignette effect f.e. (default center is 50%x50%
>>> with
>>> > width 50%)
>>>
>>> MLT does accept percentages for spatial parameters - such as
>>> everywhere you get the rectangle widget. We'll have to see what JBM
>>> says. I am sure he knows this, but decided not to for a reason - maybe
>>> as simple as control and certainty. Certainly, if you enable a Distort
>>> option, maybe you do not want the width and height to be percentage,
>>> but Distort is generally not a good option to use. I encourage you or
>>> others to experiment with changing this parameter and widget type to
>>> use % and see how well it works.
>>
>> The reason why I decided not to use percentages is that the percentages
>> are not very handy in some cases.
>> For example let's say you have a very large image, for example 3000x576
>> pixels and want to scroll it.
>>
>> If you use percentages, setting size to 100%x100% will scale the image to
>> your video profile. If you want the image to keep it's real size, you must
>> calculate the percentage that 3000 is related to 768, and the percentage
>> being not very precise the chances that your image will be slightly
>> resized are big.
>>
>> That's why I decided to use absolute pixel numbers so that you can
>> precisely enter dimensions... I do however understand that having
>> percentages can be nicer and currently the geometry parameter for the
>> vignette effect does not seem usable...
>>
>> regards
>> jb
> after some look into vignette and mlt_geometry i saw, mlt_geometry can
> handle float values. vignette not at all  (this can be changed).
>
> the geometry-type plugin is not the best solution for this filter. because
> it is a keyframeable filter, we could use the new keyframe settings dialog
> for more-value parameters, if this is a good idea ?

Yes, and you can still use mlt_geometry to handle the keyframing. Just
because mlt_geometry provides a tuple of 5 float values does not mean
you have to use all 5; you can just use 1. And, you can just interpret
the float as an integer.

Looking over vignette parameters in MLT, I think you should keep a
keyframable kdenlive geometry widget for the x, y, and radius and
opacity. I would change the MLT vignette filter to accept the classic
gemeotry of x, y, w, h, opacity and interpret w and h as a radius -
choose the lesser of the two and divide by 2. Then, put the smooth
into a new property. I am not even sure it would be that important to
keep smooth as keyframable at this time.

> So we could handle change of resolution of project video size, without
> changing anything.

Maybe for vignette, but JBM provided a good example case where % does
not work well for the composite transition. It is not limited to
panoramic scans either. Maybe there can be an option to turn off the
scalable/% option. There are things to explore too, like what happens
with titles. But all of this is not a very high priority IMHO.

-- 
+-DRD-+