[Kdenlive-devel] reverse playback

[Dan Dennedy]

On Thu, May 17, 2012 at 8:17 AM, Simon A. Eugster <simon.eu at gmail.com> wrote:
> Hey Alexandre,
>
> Realtime always depends. Some Apps pre-render when playing and then play
> this rendering when replaying the section so it is always real-time (I
> want to have this too!). But just by seeking H.264 will most likely not
> be real-time.
>
> Reversing a video could be done by hand with ffmpeg. frei0r effects
> cannot do it. MLT could perhaps (I guess it can if someone does it).

It is possible in MLT (minus sound) as part of the framebuffer
producer in the kdenlive module as authored by jb, but it has been
tricky to get integrated into Kdenlive. A long while ago, I worked on
a patch, but did not finish it. Maybe this can be addressed during
refactoring. I forget at the moment what made it so tricky because at
first it seems rather trivial to handle a negative speed value or set
a flag. Meanwhile, one can make a MLT XML clip wrapper for the real
clip with reverse applied, and then load that .mlt. But as you point
out, performance will often be atrocious, so maybe it is better to
prevent support headaches by forcing people to transcode to an
intermediate file in order to reverse (added somewhere as kdenlive
job).

> Simon
>
> PS: slowmoVideo can too ;)
>
> On 09.04.2012 00:57, Alexandre Prokoudine wrote:
>> Hi,
>>
>> Over a last month or two I heard half a dozen of questions from
>> different Kdenlive users, whether reverse playback effect is in
>> works/plans. I wonder: is it doable as realtime effect at all?
>>
>> Alexandre Prokoudine
>> http://libregraphicsworld.org
>>
>> ------------------------------------------------------------------------------
>> For Developers, A Lot Can Happen In A Second.
>> Boundary is the first to Know...and Tell You.
>> Monitor Your Applications in Ultra-Fine Resolution. Try it FREE!
>> http://p.sf.net/sfu/Boundary-d2dvs2
>> _______________________________________________
>> Kdenlive-devel mailing list
>> Kdenlive-devel at lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/kdenlive-devel
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> Kdenlive-devel mailing list
> Kdenlive-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/kdenlive-devel



-- 
+-DRD-+