Increasing clip speed causes weird issues


I’m new to shotcut and am getting strange issues. I made one video that turned out great; part of that video required a timelapse - for these, I used shotcut’s speed property. I had a music track below the entire video which player really well for the whole duration.

Now, however, as I make a second video, I am doing something similar, except I’m getting the following weird issue.

  1. If I speed the thing up to say 10x or 12x, all’s well
  2. If I speed up higher than that, a few things arise
    -The entire video speed is much faster for that clip (not the clip speed -> the actual video playing speed. The video plays normally until it reaches the timelapse clip, then suddenly the entire video is playing faster, i.e. the timeline marker is moving faster - so even though the video says for example “duration 30 seconds” in properties, in fact the clip only lasts about less than 10 seconds)
    -The music below the clip, which played just fine for the beginning non-timelapsed section of the video, also speeds up, because the speed of the entire video speeds up for that one clip.
    -Anything after this clip is played normally, i.e. the timeline cursor marker (what the heck is it called haha) slows down to a normal pace after the timelapsed clip completes.

I hope my question/issue makes sense, please if someone can help me with this I’d really appreciate it. I don’t understand why shotcut insists on suddenly speeding up the video. It’s definitely not just an editor bug - the exported video is also much faster than it should be in those timelapsed sections & the audio is also faster.

What version number of Shotcut are you using?

I downloaded it a few weeks ago. It says in my files that the version number is 19.12.16

A new version was just released a couple of days ago. Here is the link. Test on it to see if the issue still happens.

Hey, I just tested it with the new version of Shotcut, and the same thing happens. Requesting assistance.

Are we speeding up one clip, more than one clip, 1 track, more than one track, the master?
Video Mode?
Source Video(s) FPS/Resolution?

Uhh I’m just adjusting the speed property of one clip or many clips, they’re at lossless quality 6fps (for timelapse) and while at 10x speed they work fine, but when at anything over 12x speed the entire video speeds up. Genuinely I have no idea if I’m somehow tinkering with things beyond the scope of just the one clip, but I don’t think so.

EDIT: I’m using OBS, set to lossless quality 6fps for the source video. The format is avi.

The duration of the clip, next to the speed property, says 53 seconds after applying 15x speed, but it ends up taking only about 9 seconds to actually play.

6fps? Not 60fps?

Yes this happened with tracks at 3fps and 6fps. As I clarified above, I used these small fps values for timelapses. All I changed was the speed variable from 12x to 15x. I don’t see why the fps value should change whether or not the entire thing decides to speed up. The key here is that the video should take a little under a minute but ends up taking 10 seconds due to the timeline cursor speeding up during that clip. I really need someone to help me out with this, it seems to be happening for no reason.

You can upload the project file that has this problem and give the time in the timeline at which this clip with speed change occurs.

Today, I made a 6 fps lossless AVI in OBS and tested this out as best I could with the info provided. I changed the speed of the clip multiple times in case that was a trigger. I did not reproduce it.

Regarding Duration in Properties, it shows the duration of the source media with speed applied - not the duration of the timeline sub-clip for when the clip is trimmed. So, the duration problem you experience might be a result of not considering that.
My clip was 2:34;19 ~= 154.5 seconds. 154/15 ~= 10.3 secs, which corresponds to the duration you see in my screencast.

I will upload my file when I get the time but essentially the difference between your situation and my situation is that for me, when Shotcut gets to the sped up video, the line that shows what time the video is at suddenly speeds up. I understand that the duration represents that of the source media with speed applied. Your duration reads 10.3 seconds and the clip lasts 10.3 seconds - my clip’s duration with speed applied is something like 53 seconds and it takes 10 seconds to play.

Unbelievable, it isn’t doing it anymore for some reason!!! Wow, this program is making me think I’m crazy haha. Well, in any case I suppose it fixed itself for now… but I’m sure we can all agree that that is an extremely odd situation. Hopefully this bug does not come up again…

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