Created attachment 101365 [details]
corruption

Notice how the project monitor plays a clip even though the timeline is empty.

So after the corruption happens, close the project and start it again. You will see duplicated clips created. Those clips are invisible in the timeline before restarting the project. (See video.)

That looks eerily familiar. 

In all honesty, I don't think kdenlive handles the changing of the clip length in the timeline very well. The speed effect is thoroughly broken, and really should be depreciated and get a warning. 

The good news here is that the "reverse clip" clip job has been modified to handle any speed form -10,000% to 10,000%. 
This gives you an .mlt file with the desired speed. Kdenlive's handling of .mlt files is rock solid, and you get sound support thrown in for free, even if you have automatically split video. Also, proxies work on .mlt files. 

I hope this helps?

*** Bug 371808 has been marked as a duplicate of this bug. ***

I don't understand how use "reverse clip" for change speed. Can someone explain me?

(In reply to Aleksey Samoilov from comment #5)
> I don't understand how use "reverse clip" for change speed. Can someone
> explain me?

You will get better help asking in the forums, g+ community or mailing list.

*** Bug 373480 has been marked as a duplicate of this bug. ***

I want so much this bug to be fixed! It's pretty hard to work with kipping in mind that you can't select speeded clips with Shift. May I donate or do something else to force the fixing?

(In reply to Mikhas' from comment #8)
> I want so much this bug to be fixed! It's pretty hard to work with kipping
> in mind that you can't select speeded clips with Shift. May I donate or do
> something else to force the fixing?

Mikhas' I know how you feel and I have stopped using the speed effect in Kdenlive due to the corruption issues. We are starting to do a timeline refactoring to fix all this corruption issues and will is due to be released in April. Please contact the mailing list to see ways how you can help out. 

Thanks for your support.

Tried the speed effect again, just to see it disappearing on project reload. Sad. Still using ffmpeg to render separate variants of the clips where I need to change the speed.

(In reply to Wegwerf from comment #10)
> Tried the speed effect again, just to see it disappearing on project reload.
> Sad. Still using ffmpeg to render separate variants of the clips where I
> need to change the speed.

hopefully all this timeline corruptions will be fixed after the refactoring.

Seriously, the speed effect is broken. 

Just use the "reverse clip" clip job and set a playback speed. 
This is the only way I can reliably change the playback speed of a clip in kdenlive and not have the corruption issues.

*** Bug 374488 has been marked as a duplicate of this bug. ***

*** Bug 379106 has been marked as a duplicate of this bug. ***

I experience similar symptoms without using speed effect. Instead I'm an avid user of ripple delete (mark in, mark out, shift-x). A similar situation eventually happens, duplicate clips created, they cannot be moved or deleted, timeline has empty spaces that cannot be fixed. Restarting kdenlive sometimes helps. This bug is frequent, but very hard to reproduce on purpose.

(In reply to svofski from comment #15)
> I experience similar symptoms without using speed effect. Instead I'm an
> avid user of ripple delete (mark in, mark out, shift-x). A similar situation
> eventually happens, duplicate clips created, they cannot be moved or
> deleted, timeline has empty spaces that cannot be fixed. Restarting kdenlive
> sometimes helps. This bug is frequent, but very hard to reproduce on purpose.

Soon we will release an alpha version of the refactoring branch which will fix this issues. Stay tuned and help us test it if you can.

Thanks.

> Soon we will release an alpha version of the refactoring branch which 
> will fix this issues. Stay tuned and help us test it if you can.
Excellent news!
I will be happy to test, but I'm a Windows user and I guess the fix will take a while to propagate to the Windows builds?

(In reply to svofski from comment #17)
> > Soon we will release an alpha version of the refactoring branch which 
> > will fix this issues. Stay tuned and help us test it if you can.
> Excellent news!
> I will be happy to test, but I'm a Windows user and I guess the fix will
> take a while to propagate to the Windows builds?

Well, our great vpinon, just released a windows build for the refactoring version: 

https://files.kde.org/kdenlive/unstable/kdenlive-refactoring-20170621-w64.7z

NB: Remember this is pre-alpha software.

same here. a bug i remember from 0.9.8

When applying the speed effect, often the timeline gets messed up in an unpredictable way, one thing that happened to me (on larger projects, so it is hard to reproduce with a view steps): the effect works well, but other clips get messed up or become invisible , but play back correctly. also vice versa: clips added to the timeline get played back correctly, but when i render the timeline the new clip stays black, etc.. 

@evert forster this is a helpful information! the speed effect would better just be removed! or what i did lately: open a project with the one file you need the speedeffect, render it out "lossless" with the speed effect and insert it into your project.. it s cumbersome, but safes you from messing up everything..

*** Bug 372819 has been marked as a duplicate of this bug. ***

*** Bug 376915 has been marked as a duplicate of this bug. ***

So speed effect is totally broken on 17.12.0. It use to work for me at least with 17.04. Now there is no way to do slow motion? Clip job duplicate with speed change wont work either...

Riku, the duplicate clip with speed change being broken is a new bug. I'll play with it a little and then put in a bug report. 

Kind regards,
-Evert-

(In reply to Evert Vorster from comment #23)
> Riku, the duplicate clip with speed change being broken is a new bug. I'll
> play with it a little and then put in a bug report. 
> 
> Kind regards,
> -Evert-

AFAIK, the current code base is not maintained so this bug will not get a fix. After the timeline refactoring is finished, the devs will introduce a rewritten speed effect fixing all these issues.

Hi there, Riku. 

I personally use a package called SlowmoVideo. It very slow, but does interpolation between frames and is very high quality. I did submit a bug, it might be a quick fix. 

Kind regards,
-Evert-

I'll check that. Thanks.

*** Bug 401037 has been marked as a duplicate of this bug. ***

Finally :D