Bug 494036

When you drop a video clip onto the timeline, you can click and drag the ends of it to make it shorter and longer. Right now, you can't make the clip longer on the timeline than the clip itself actually is. I would love the ability to do this, and have kdenlive automatically generate more footage for me using probably one of two modes: looping or extending the last frame.

What I would imagine this looking like is that by default, you get the current behavior. But you can right click a clip and set its "extrapolation mode" or something to either None (default), Loop or Extend Last Frame. If you choose an extrapolation mode, now you can stretch the clip past its actual length. The extended portion of the clip is visually distinguished somehow in the timeline. Ideally you could set a different extrapolation mode for the left and the right parts of the clip.

Currently I do looping by copy-pasting the clip, and I do extend last frame by moving the timeline as close to the last frame as I can get it, then right clicking and doing "extract frame to project", and dragging that into the project. This is inconvenient, error prone and pollutes my project with a bunch of image files.

This would be a gamechanger for people making animation based informational videos. You make a little animation loop to be played while voiceover rolls: you drop the loop into your timeline and just extend it until the voiceover is done. You make an animation of some information appearing on screen, and then you want the information to stay on screen while voiceover rolls - just drop the animation in and extend the last frame. In my current project I am constantly needing to do these two things. 37% of the clips in my timeline right now exist only due to having to work around this missing feature.

FEATURE SUMMARY:

- Each video clip in the timeline can have an "extrapolation mode" set to either None, Loop, or Extend Last Frame. By default, this mode is set to None.
- You can set this mode by right clicking the clip in the timeline.
- Ideally, it could be set independently for the left and right sides of the clip.
- Probably you would also have a new panel similar to the current "Effects", "Clip Properties" etc panel called "Extrapolation" in which you could set this mode for the left and right sides independently.
- When a clip's mode is set to None (on a given side), it behaves as it does currently, i.e. it cannot be extended past its actual length (on that side).
- When set to Loop, extending the clip on that side will loop the clip.
- When set to Loop and the clip is extended, some visual indicator on the clip in the timeline indicates the loop points. These indicators act as snap points in the timeline. This is important, because sometimes it's important to have a discrete number of loops, for example because you want to loop Clip A, then go to Clip B whose first frame is designed to match the last frame of Clip A.
- When set to Extend Last Frame, extending the clip on that side will extend the last (if extending from the right) or first (if extending from the left) frame of the video, like a static image clip.
- In either case, some visual indicator on the timeline shows which part of the clip is "original" and which part is "extended". For example, the extended portion could have cross hatching/stripes over it. These indicators act as snap points. In particular, it is easy to click and drag to shorten the clip and remove the extended part, because the clip will snap to that point.
- If a video has been extended and the user sets its extrapolation mode (on that side) back to None, it snaps back to its original length, in such a way that the "original"/unextended portion of the clip does not move on the timeline.