You haven't listed your computer hardware or the type of video files you are working with.

If I have to slow down a clip, I usually use Ctrl+Left Mouse button and drag the clip to the right.

Sorry, I don't normally post here so I'm not used to it. Here's some info about my PC:

Processor    Intel(R) Core(TM) i5-7500 CPU @ 3.40GHz   3.40 GHz
Installed RAM    16.0 GB
System type    64-bit operating system, x64-based processor

If more is needed please let me know what I should share!

Video file info:

General
  Name: Tangled.mp4
  Folder: F:\Collective\Vidding\Films & Shows
  Type: AVC
  Size: 3.05 GB (3,122,265,305 bytes)
  Created: Thursday, January 28, 2021, 11:09:45 AM
  Modified: Thursday, January 28, 2021, 11:16:11 AM
  Accessed: Thursday, June 23, 2022, 4:49:18 PM
  Attributes: Archive

Streams
  Video: 01:40:17.135, 23.976 fps progressive, 1920x1080x12, AVC
  Audio: 01:40:17.216, 48,000 Hz, 5.1 Surround, AAC

ACID information
  ACID chunk: no
  Stretch chunk: no
  Stretch list: no
  Stretch info2: no
  Beat markers: no
  Detected beats: no

Other metadata
  Regions/markers: no
  Command markers: no

Media manager
  Media tags: no

Plug-In
  Name: compoundplug.dll
  Folder: C:\Program Files\VEGAS\VEGAS Pro 17.0\FileIO Plug-Ins\compoundplug
  Format: AVC
  Version: Version 17.0 (Build 284)
  Company: MAGIX Computer Products Intl. Co.

The reason I prefer to use the Slow Motion plugin instead of Velocity or the click-drag method is because the Slow Motion plugin gives a very smooth, cinematic effect. I was very excited to have it in my new copy of Vegas 17, but I'm still learning about it.

Also you can see the glitchiness in this video:

Oh, that is ugly. It also depends on the framerate of the actual video. The more frames per second it is recorded at, the smoother the slow motion will be. So what the fps of the video?

Oh, that is ugly. It also depends on the framerate of the actual video. The more frames per second it is recorded at, the smoother the slow motion will be. So what the fps of the video?

It's listed in the info I gave, 23.976 fps. The thing is though, Vegas themselves said that the Slow Motion plugin is supposed to work well even with low framerates.

The Slow Motion effect in VEGAS Pro utilizes Optical Flow for smooth slow motion even with lower frame rate footage like 24 fps. As we mentioned above, it’s often hard to get smooth slow motion with frame rates like 24 fps because there aren’t enough frames for slow motion to work well, resulting in choppy-looking playback, and you may find the same problem with higher frame rate footage like 60 fps if you slow it down a lot.

Unlike the other methods of slowing footage, which repeat frames or blend existing frames, the Slow Motion effect generates new frames. It interpolates the positions of moving objects and creates whole new intermediate frames. The result is better, smoother slow motion.

https://www.vegascreativesoftware.com/us/video-effects/how-to-speed-up-slow-down-videos/

Here's what happens when I change the slow motion method from Optical Flow to Morph:

Slightly better, but still weird.

Interesting. In Vegas 19, it doesn't have the features listed in the article. I wonder why it's changed.

But it does have to "create" the needed missing frames, and it isn't always perfect. How much have you slowed it down? Have to tried a lesser percentage to see where it "breaks"?

Interesting. In Vegas 19, it doesn't have the features listed in the article. I wonder why it's changed.

But it does have to "create" the needed missing frames, and it isn't always perfect. How much have you slowed it down? Have to tried a lesser percentage to see where it "breaks"?

It seems to still do it whether I have it at 25%, 50% or 70%. What's weird is after I turned off GPU acceleration last night, it seemed to have fixed it. Now today it's got issues again. It's just frustrating. :/ And I can't really find anyone else who's claimed to have this problem.

Do not expect miracles, it's not possible to get smooth slowmotion of fast moving objects at such low framerates. No problem as long when objects do not move fast.

Do not expect miracles, it's not possible to get smooth slowmotion of fast moving objects at such low framerates. No problem as long when objects do not move fast.

Well in that case, I guess for now I'll just try out Twixtor or something.

@StardustCreations Are you able to link to the piece of media you're using, upload to a file sharing site and link or if it's online, link to that

@Former user I tried it with a few other movie copies I have as well, and it does similar things. I think all of my footage is in 23.976 because that's just how it comes.

Here's a link to what I'm using in particular, hopefully it works: https://www.mediafire.com/file/t5igm39omto71kc/Tangled.mp4/file

Just noted something interesting: When I set the quality to Coarse instead of Fine, it actually looks better?? Who'd have thought.

I tried with the free slowmotion app - Flowframes, works as expected, so no timing problem with your source media. There has been a few posts about Vegas Optical Flow not working very well. It's something they have to fix

I tried with the free slowmotion app - Flowframes, works as expected, so no timing problem with your source media. There has been a few posts about Vegas Optical Flow not working very well. It's something they have to fix

Flowframes? :o I've never heard of that one. Should I try it instead?

Thanks for testing it out yourself, I appreciate it! That clip looks really great with what you did.

@StardustCreations I see your slowmo example is more like 4x , than the 2x I tried, at 4x where the AI needs to create extra frames you can see some artifacts, but it is still working much better then Vegas, but not perfect

https://nmkd.itch.io/flowframes He's asking for money but don't pay. Instead if you find the app useful sign up to his patreon for the newest versions, instead of paying for old versions. A strange business model.

Yes, Vegas Optical Flow is far from perfect (and terribly slow compared to Davinci Resolve). I use flowframes mainly for converting 25fps recordings to 50fps, but it can also be used for creating slomos at 2x, 4x, 8x and 16x.

I tried downloading, but it says (at this moment), Permission Denied. But I am curious if you drag the clip using Ctrl+Left Mouse button, are the results the same?

@Reyfox Oh it got copyrighted, here it is on a different site: https://mega.nz/file/1aBQHCqA#BFSTTs0eR_9nLcYAQKWO13dFk7ujj_EzGmKaCexMJnE

No, using the click-drag method doesn't make that happen, but that's because it's using a different method to slow it down. I usually use the Velocity envelope, but I'd rather use the Slow Motion plugin effect because it's more smooth and cinematic. I've always wanted to be able to make slow motion look like that.

So thus far, the two things that I've found make a huge improvement are: turning on GPU acceleration, and setting the effect quality to Coarse (ironically).

@StardustCreations thanks. Downloaded and I'll give it a go this weekend.

If it comes down to glitchy video or a smooth video, I'll take the one that gives the best visual experience. Sometimes, there are trade offs we have to work with.

Update: It seems that after updating to build 387, setting the quality to Coarse actually causes glitches in the rendered video, and Fine does not. *sigh* Just continuing to experiment xD

@StardustCreations Hi, just thought i'd let you know, i had a play with this, Vegas's Slow Motion was a pain, i sacked that off very quickly, Stretching the clip or changing the Playback rate in Properties did a better cleaner job, but as @3POINT & maybe others have mentioned 23.976fps is going to look stepped when stretched, I tried adding Motion Blur, that didn't help, Boris has BCC Optical Flow & S_Retime, each tries to fill in the missing frames with those adjacent but neither did a good job, it just looks like a ghosting type effect, or if you use the fx's controls to sharpen it you start getting glitching, artifacts or distortion of the surrounding image, 🤷‍♂️ Just thought i'd share 👍

Here the hair as it falls rather than been stepped it has a natural motion blur to it, that looks ok when played 👍

but the woman coming up has a ghost edge to her

Change the setting to loose the ghost

& then the hair looks crap n blotchy, edges not smooth n blended :/

The Blending control top right in the Video FX window can be keyframed & i had a play which did improve it, moving from one setting for as the woman comes up & then changing it for as the hair falls, but filling in those missing frames ....

@Former user I appreciate you fiddling with it, thank you for sharing your findings! I don't have that BCC Optical Flow thing, perhaps I'll look into it.

@StardustCreations Hi, it's part of Boris Continuum $695 for the licence. sorry i think what i was just trying to show was that even with fairly expensive software, extended 23.97fps & so slowing it down is not easy to then fill in the gaps between frames to make it look right.

PS the last one @Former user posted doesn't look too bad..