Again: Reverse clip (and speed effect)

I still don't really understand why the otherwise so full-featured kdenlive does not allow to reverse a clip (play it backwards), especially because MLT includes such a feature.
Maybe the reason is, that combining reverse with the speed effect does not seem to work.

As a workaround for the missing reverse effect, I am creating a .mlt file with something like this:

melt -consumer xml:reversed.mlt

The '?-1' reverses the video and the resulting .mlt file can be used in a kdenlive project just fine.

However, applying the speed effect in the project to such a clip does not seem to work; the clip plays (also after rendering) at the same speed.

So I tried to apply both reverse and speed (i.e. 500%) in the same command:

melt -consumer xml:reversed.mlt

This *seems* to work but when adding the resulting .mlt file to a project, the clip is somewhat messed up - it plays reverse at the changed speed, but only a part of it, so it is unusable.

Question: Is this a kdenlive or MLT issue? Is this the reason why a reverse effect is not available in kdenlive?


Yes this is a very commonly requested feature. I started this feature request where I was suggesting that we have reverse added to the clip jobs menu item - it would sit there with transcode and stabilize and would run on the clips to produce .mlt output which you could then load into the time line. This would just be automating what dode is already doing here.

It seems to me( naively) that this might be fairly easy to do since the clip job framework is already in place to execute melt jobs and put the resulting .mlt files in the project tree.

Dode - when you say the speed plus reversed clip is unusable - is this observed in a rendered version or just in preview? Because perhaps it is asking a lot of the preview mode to do the reversing and the speed effect on the fly.

When I was playing with reversed video I found it was better to render my reversed video into some lossless format and then work with that rather than working with the .mlt file. This just reduces complications.

My feature request has gone nowhere. But if people think it is a good idea maybe they could say so on the mantis. And this might help it get up. :-)

ttguy, I had another look at the clip with speed plus reverse effect, the problem is the same for the preview in the monitor as for a rendered video.
An example: A 30 second video reversed and at 5x speed correctly shows up as reversed 6 second video, but plays only for about 1 second, for the remaining length it only shows a still image.

I ended up doing the same as you to avoid this, I simply rendered out a reversed .mlt clip and then applied the speed effect. For anything else I have used so far (effects and transitions), the reversed .mlt clip seems to work just fine in kdenlive.

So maybe the only issue with reversed clips is that it can't be combined with the speed effect, and I guess this is an issue in MLT.

I am going to vote for your mantis.

j-b-m has implemented this now

Yay. Thanks jbm. Will test as soon as sunab builds it !