[Kdenlive-devel] REVERSE MOTION

Dan Dennedy dan at dennedy.org
Fri Sep 16 16:42:41 UTC 2011

On Fri, Sep 16, 2011 at 3:27 AM, Marco Ciampa <ciampix at libero.it> wrote:
> On Thu, Sep 15, 2011 at 02:41:41PM +0200, Elbground Multimedia wrote:
>> Hi Dan & other developers,
>> Still a layman and ignorant of anything beyond using the User
>> Interface, one question:
>> If it already is integrated in the speed effect, why can't it simply
>> be applied by entering a negative speed percentage (i.e. -100 for 1:1
>> reverse motion) in the speed effect parameters? That, to me, seems the
>> easiest and most conventional (i.e. similar to other applications such
>> as Final Cut) way to solve the issue.
>> Kind regards, Ingar
> naaaaahhhh too simple! ;-)

Heh. It is only simple to make the UI widget permit negative numbers. :-)

My first kdenlive patch submission a long time ago used negative
speed. The problem is that the speed is used to calculate an effective
duration throughout many places of the Kdenlive code. Therefore, with
negative speed, you get a lot of places with negative duration! My
patch addressed most of those by using the speed's absolute value, of
course. But there were some unaddressed corner cases making the patch
incomplete, and I was busy with MLT.
Now, another way is to convert negative to a reverse flag, which MLT
also accepts. I recently looked into that, and there are several
places in Kdenlive code that need to be touched to carry and handle
the reverse flag. Alas, I remain busy with MLT and not being that
fluent with the kdenlive code and being this close to release, I did
not want to introduce  that change at this time.


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