Change clips speed
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It would be *really* nice to modify the speed of a clip.

Thanks for the good work!

Imported from


Differential Revisions
D276: When a GESEffect is used that changes the playback rate, such as the 'pitch' element, correct for it when sending seek events to the source.
git URI
lavish claimed this task.Sep 1 2009, 4:21 PM
lavish created this task.
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jeff added a subscriber: jeff.Aug 12 2015, 3:46 PM
jeff added a comment.Sep 2 2009, 2:14 PM

See also for some initial/potentially incomplete thoughts (as indicated by Ed's comment on that post) about how it could look/behave like in the UI.

jeff added a comment.Feb 6 2010, 11:41 PM

Am I right assuming that this would use the "videorate" gstreamer filter, or would it be something else? Would it be easy-enough to implement to be part of ?

I really love the proposal in the blogpost mentioned in comment 1. It seems like a very intuitive way to handle it.

To address the issue of reversing the direction, it might be better to keep that functionality separate. Is it really that natural to think of reversing a clip as stretching it negative? What if you just had an option to 'reverse' a clip. And then just use the tools as described in the blog post to speed up or down?

I think this should be actually handled with the new pane like we can see here:

I am going to work on that after my branch is merged I think. It seems to be pretty important.

seeed added a subscriber: seeed.Aug 12 2015, 3:46 PM
seeed added a comment.Nov 29 2010, 3:58 AM

On the backend side, is seeking the good way to go to adjust rate ?
I tried that today and it worked :

that is changing the playback rate for the entire pipeline. What this bug is about is changing the playback speed of an individual clip in the timeline. To do this you only need to set media-duration != duration for the clip. If media-duration is < duration, then playback is slower than normal. If media-duration is > duration, playback will be faster than normal. This is the rationale for having two separate duration properties.

The real question is how to expose it in the UI. Here are a few ideas, which we should definitely talk over with users:

  1. bring up a dialog and enter a percentage
  2. use a modifier key so the user can "stretch" or "squeeze" a clip (as opposed to trimming it
  3. this could be an application for a regions (which haven't been implemented)
seeed added a comment.Nov 29 2010, 9:42 PM

What I thought about was rather a simple spinbutton that would be set sensitive when the clip is selected. Its simple and efficient, unless you want to get other parameters from the user.

jeff added a comment.Nov 30 2010, 2:27 PM

@Brandon in comment 6 and comment 7: okay, that's for setting a uniform speed over the entire clip... but what about motion ramping (variable speed inside a clip) such as demonstrated in the link in comment #1 ?

@Mathieu in comment 8: I don't see where this spinbutton would go, except in the eventual "clip properties" tab (which is currently disabled because there's nothing in it)

seeed added a comment.Nov 30 2010, 5:26 PM

The point is what I could implement without coding in C would pretty much be only setting a uniform speed over the entire clip.
And the spinbutton in my mind would go down, besides the "ungroup" button.

To clarify, a new gstreamer element would be needed to do motion ramping, which would probably need to be written in C and added to GStreamer.

I have done a little digging and there is an underlying problem somewhere in PiTiVi. This will have to be fixed at some point before we can implement this feature.

I created a project with a single clip in it. I edited the media-duration values such that the clip would play at half speed. The video portion does play at half speed, but not the audio. On the other hand, a simple test script I wrote in python seems to work at slowing down audio playback. So it should work in pitivi -- it just doesn't.

pitivi-maint triaged this task as Enhancement priority.Sep 1 2009, 4:21 PM
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thiblahute removed pitivi-maint as the assignee of this task.Sep 16 2015, 1:41 PM
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thiblahute removed pitivi-maint as the assignee of this task.Sep 16 2015, 1:45 PM
sgielen claimed this task.Oct 25 2015, 9:41 PM
aleb added a comment.Nov 23 2015, 11:46 PM

How should the UI look like? We could have in Clip Properties > Transformation something like:
Speed: [ 1|-|+] (4 seconds)
-/+ would work in .1 increments.

I think if we call it "Rate" then it would not be consistent with the project settings UI where the framerate can be edited using a separate combo and entry. Considering this, the "rate" could be changed to "speed" in the code.

sgielen set git URI to git:// 15 2016, 1:02 AM
thiblahute added a comment.EditedFeb 17 2016, 12:37 PM
(ptv-xdgapp) ➜  gst-editing-services git:(master) ✗ git phab checkout T2344
git log
Git URI: git://, branch: wip/phab/T2344-applyrate5
Traceback (most recent call last):
  File "/usr/bin/git-phab", line 1068, in <module>
  File "/usr/bin/git-phab", line 968, in run
    getattr(self, method)()
  File "/usr/bin/git-phab", line 806, in do_checkout
    commit, remote_branch_name = self.fetch()
  File "/usr/bin/git-phab", line 788, in fetch
    self.repo.git.fetch(remote, "%s" % branch)
  File "/usr/lib/python3.5/site-packages/git/", line 440, in <lambda>
    return lambda *args, **kwargs: self._call_process(name, *args, **kwargs)
  File "/usr/lib/python3.5/site-packages/git/", line 834, in _call_process
    return self.execute(make_call(), **_kwargs)
  File "/usr/lib/python3.5/site-packages/git/", line 627, in execute
    raise GitCommandError(command, status, stderr_value)
git.exc.GitCommandError: 'git fetch git:// wip/phab/T2344-applyrate5' returned with exit code 128
stderr: 'fatal: Couldn't find remote ref wip/phab/T2344-applyrate5'

You should set your git config phab.remote to your repository, morevover that has to be readable by the outside world (you can configure git remote set-url --push)

sgielen changed git URI from git:// to 17 2016, 1:16 PM

Ok, I just updated the diff to point to Github, branch wip/phab/T2344-applyrate5. Did that go through correctly?

Hold on, the current URI looks like it's SSH. I'll try setting it to git://.

sgielen changed git URI from to git:// 17 2016, 1:18 PM

Try now :)

thiblahute closed this task as Closed.Feb 26 2016, 6:54 PM
thiblahute reopened this task as Open.Sep 11 2016, 6:28 PM
yajo added a subscriber: yajo.Oct 18 2016, 6:53 AM

I'd just like to add a suggestion: smooth enter/exit of this effect. It allows better-looking transitions from normal video to slow/fast video. Android's PowerDirector has this option and it is very nice, in case you want to see an example of what I say.

aleb renamed this task from change clips speed to Change clips speed.Oct 19 2016, 3:50 PM
aleb removed sgielen as the assignee of this task.
aleb added a subscriber: sgielen.

We know have everything in place in GStreamer (ie videorate is now able to change clip speed) so it is really a matter of sitting down and implementing a proper UI/workflow over it :)

aleb added a comment.EditedNov 12 2016, 6:37 AM

It won't be possible to change the speed of only a portion of the clip. It will be possible to set the speed of the entire clip initially.

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csoriano1618 closed this task as Closed.Feb 23 2018, 6:37 PM