Improving the Speed filter


I’ve been playing with the Speed filter and wanted to share some thoughts on how it could be improved. Shotcut is great software and I appreciate how much I can accomplish is so this is just a suggestion and I understand people’s time is limited, even if they agree with the suggestions below.

  1. Seeking into the middle of a clip after speed changes does not bring to the time that the clip would be if played from the beginning. Making precise adjustments can be tedious having to rewatch the entire clip again.
  2. It would make editing easier if the clip length would shorten/lengthen with changes, like how adjusting the speed in properties works.
  3. Being able to make it more than 10x faster would be handy.
  4. If I take a clip, and cut it up in timeline, and modify sections of it to be faster, it pulls in portions later in the clip, rather than editing the clip as its own stand-alone element. This makes it hard to take a single scene and cut it up and then apply the speed filter to a portion because I have to manually figure out where it should match up with the following clip.

Hope those make sense. Thanks for making Shotcut, it’s really great and a pleasure to use.

Thanks for your comments.

This issue was reported here and is fixed for the next release.

This was considered during the original implementation. But it creates too many side effects. Will the length of the clip grow and shrink dynamically as a user pulls a keyframe up and down on the filter? What will happen to clips after the affected clip? With they be moved or overwritten? No one has volunteered to tackle all the complications that would come from this.

I am open minded about this. I chose 10x as the limit because it seems like faster than 10x just looks like a slideshow. If someone needs more than 10x, they can use the speed parameter in the clip properties.

Also, common speed adjustments in the range of 1x-2x become difficult if that range is only the tiny 5% left side of the slider with the right 95% use for less common 2x-20x speed adjustment.

My intention is that you would not cut up the clip. Instead, configure the keyframes in the filter to be 1x speed until the section that you want to speed up. Then, when you are done speeding up, and go back to 1x speed, just leave the speed filter at 1x for the rest of the clip. No need to do any cutting.

Oh that’s fantastic!

Yes it is tricky. Do you see an analog between that and modifying speed via properties, because that has similar issues (albeit simpler interface). For what it’s worth, I feel like the Ripple options could apply in that case and make sense. Or the rules around changing speed in properties would apply. Another option is maybe a Filter doesn’t make sense for this sort of thing and having a specialized editor would, just because it’s such a funky thing.

I have some clips that I go much faster. Is there any way to not have a limit? For what it’s worth, I almost never modify the value in a keyframe by dragging the keyframe up and down, I just type the value I want in.

The main reason I use the Speed Filter is the gradual speed up/slow down I can do with keyframes, which makes the speed property less ideal. Combined with the cutting a clip challenge below, switching between the two hasn’t been a viable option IME.

Perhaps my suggestion here is really a biproduct of the other challenges with the speed filter. I started cutting frames because applying a complicated set of keyframes to a filter was becoming frustrating due to the clip length + seek bug. With the seek bug fixed, maybe that isn’t as much of a problem anymore. One situation that I had trouble with recently, and maybe I just need to practice more, is I had a specific point that I wanted to come back down to 1x, and I was struggling to hit that point properly when I had the clip at 10x, my keyframe would always be off for some reason. Combined with the seek bug, it was difficult to get it right. So I just cut the un-filtered clip where I knew I wanted it to be and then tired editing the part I wanted speed up, and ran into this.

Thank you for the responses. I’ll play more with the filter to see how much of this is my own issue vs something inherent to the filter.

Would it be possible to change the speed of a clip by pushing or pulling the end with Ctrl pressed? The priority would not be the exact duration, but the desired place in the timeline. Many other editors have exactly this function.