I have not been able to figure out how to apply transitions with a clip that has the speed effect applied to it. I'm not certain whether this is a bug or a conceptual problem on my part. However, using the speed effect on a clip appears to cause transitions to be ignored (a sudden cut occurs both when previewing and when viewing the "rendered" video).

To repeat this (tested in Kdenlive 0.7.x and 0.8.2):

1) Load a video clip (it does not appear to matter what the source is)

2) Cut it into two parts so you have some video to use

3) Apply the "speed" effect to the second clip (it doesn't matter whether you apply it to the first or not)

4) Overlap the 2nd clip over the first (doesn't appear to matter which track is on top)

5) Apply a transition such as "dissolve"

My expectation is that a dissolve from the first clip to the second will occur, along with the speed effect. What happens in fact, though, is that the dissolve is ignored and does not preview or render (exactly as if no dissolve were added).

This doesn't appear to happen with other effects (e.g. "old film" or "flippo"), which makes me think this is an actual unreported bug (at least, I haven't found a bug report that matches it). But as I'm pretty new with Kdenlive, I thought I should ask and see if maybe I'm just doing it wrong somehow.

Another thought occurs to me -- if Kdenlive had a "bake" or "pre-render" option, I could route around a bug like this by applying a transition to the "baked" speed effect (of course, it is possible to do this manually, but is a PITA).

One extra bit of weirdness with this:

If I add an _extra_ effect to the 2nd track -- say "charcoal" -- then the dissolve will dissolve from the 2nd video with only the speed effect to the 2nd video with the speed+charcoal effect (i.e. it applies the transition BETWEEN the two effects on the SAME clip). Interesting, but I certainly was not expecting that!

Is this issue resolved? I seem to be repeating it on 0.9.8 built from source on 071414 using the MLT script. Like OP said, I'm not sure if I'm missing something about how transitions and effects work or if this is actually a bug.

The issue only appears to happen when you are using clips from the SAME file. For example:

File 1 is 5x speed in track 1
File 2 is 5x speed in track 2
I can properly dissolve from track 1 to track 2

However, if I do:

File 1 is 5x speed in track 1
File 1 is 5x speed in track 2 (yea, same file, just a different clip)
I can add the dissolve from track 1 to track 2 but dissolve is just ignored.

I assume that if I copy File 1 as "File 1 copy" and use that in track 2, then it shouldn't be a problem and that's how I'll work around it for now. Any other suggestions?

Thanks!

I suppose that the issues you are seing are in fact related to the type of source material you are using. Some time ago I learnt from a sidenote made by Dan Danedy that the speed effect to work correctly requires a source clip format that is easily seekable. I've also learned that H.264 footage is bad in this respect. Transcoding such clips from H.264 to DNxHD (using Kdenlive's built-in transcoding jobs) solves the problem and the speed effect then works as expected. This should also solve the transition issues your are experiencing as well.

TheDiveO wrote:Some time ago I learnt from a sidenote made by Dan Danedy that the speed effect to work correctly requires a source clip format that is easily seekable. I've also learned that H.264 footage is bad in this respect.

Interesting, thanks, I might try that sometime. Although before finding non-linear video editing, I was using VirtualDub to slice and splice videos which created tons of extra files. So I'd rather not have to do anything to the source files.

In case someone is interested, I found an odd solution that avoids having to make copies of the files. For whatever reason, this speed/transition effect works fine if applied to projects instead of clips. So, if I have one video file, and I want to take two separate clips from it, speed them both up, and then dissolve from clip A to clip B, it doesn't work properly.

Instead, make a new project named ClipA, import the video file you want, and then set the cropping you want for clip A. Also set your speed increase here (not as versatile, I know, but it saves on making copies of the source video). Do the same for clip B. You now have two projects, ClipA and ClipB, that can both be imported into your larger project (MasterProject). Once you import these two files, you can add the dissolve transition from ClipA to ClipB, even on H.264 (I'm using straight from the camera GoPro Hero 3 files).

If you decide to make changes on the speed settings of either clip, you will need to modify the ClipA or ClipB project, then refresh the clip in MasterProject to update them. Your alignments will be off, so fix any of that.

Hopefully that helps someone else out there.