You won't lose resolution, unless you render it to a lower resolution format. You may lose quality though. So, when you make the intermediate file you should use uncompressed or lossless formats.

One very important thing to consider is resampling. Vegas' default behavior is to blend frames when changing frame rates. This means that when you slow it down to 1/4 speed you'll end up with this:
- new frame 1 = old frame 1
- new frame 2 = 75% old frame 1 + 25% old frame 2
- new frame 3 = 50% old frame 1 + 50% old frame 2
- new frame 4 = 25% old frame 1 + 75% old frame 2
- new frame 5 = old frame 2
- new frame 6 = 75% old frame 2 + 25% old frame 3
and so on ....
This can result in ghosted, doubled images especially when there is a lot of movement. Some folks find this adds to the smoothness when slowing down, others find it very distracting.

On the other hand, you can disable resampling. In that case you'll end up with frame 1 repeated 4 times, frame 2 repeated 4 times, etc. This preserves a sharp image, but eventually as you get slow enough you end up with no movement, just jumps from one frame to the next. Of course, if you're slowing video down there isn't picture in between the frames to fill in the space, so something has to give one way or the other.

"export the file and then reload it into the project"

no need for this, just use velocity envelope (right click on the event)

Vegas Pro has the Velocity Envelope tool which gives you the ability to continually change the playback speed of your video over time.
This is the Vegas Movie Studio forum, so it's likely that the OP uses one of the Movie Studio versions.

Comparing Pro to Studio

If the information isn't there, you can only slow down so far.
If you have access to a powerful computer then it might "guess" what the interframes contain .. but there is no substitute for more data...i.e. taken at the original scene.
I have a CX410 which maybe ( since Sony won't tell!) has more info in an 11 sec file ( at normal playback). This started as 2-sec so already it is slowed quite a lot.
I understand several Sony Camcorders have this feature, but Sony is very reluctant to push this trick, it seems - AND - Pana now claims it can extract a SloMo from normal files ( taken at the greatest Bit-rate), so you don't get the 2-sec limitation.
This limitation is particularly annoying as the Sony camcorder lacks any "Trigger" mode so you can get the shot first-time. I find it v.difficult to predict when a bee will fly away from a flower, etc.

With the CX410 Camcorder SlowMo it is possible to slow it further in Studio ( SMSv12) but IMHO, that's because the data is already recorded.
Oddly these frames are not 1920x1080 - but in SMSv12 it doesn't mind and appears to correct this without my attention.... However, if you push it, then there is some definition falloff, I guess you have to pay a lot of money for a really fast sensor and the storage to go with it.

Rendering a Sub-clip and then Importing does extend SloMo but there is no substitute for "more Data" at the start, - er IMHO.


I have heard of Software that appears to create magical SloMo . . . but it is able to do this by morphing of the image between frames . . . . in general this is acceptable but in nature it's probably not right - but it will fool our eyes into believing so.

You won't lose resolution, unless you render it to a lower resolution format. You may lose quality though. So, when you make the intermediate file you should use uncompressed or lossless formats.

One very important thing to consider is resampling. Vegas' default behavior is to blend frames when changing frame rates. This means that when you slow it down to 1/4 speed you'll end up with this:
- new frame 1 = old frame 1
- new frame 2 = 75% old frame 1 + 25% old frame 2
- new frame 3 = 50% old frame 1 + 50% old frame 2
- new frame 4 = 25% old frame 1 + 75% old frame 2
- new frame 5 = old frame 2
- new frame 6 = 75% old frame 2 + 25% old frame 3
and so on ....
This can result in ghosted, doubled images especially when there is a lot of movement. Some folks find this adds to the smoothness when slowing down, others find it very distracting.

On the other hand, you can disable resampling. In that case you'll end up with frame 1 repeated 4 times, frame 2 repeated 4 times, etc. This preserves a sharp image, but eventually as you get slow enough you end up with no movement, just jumps from one frame to the next. Of course, if you're slowing video down there isn't picture in between the frames to fill in the space, so something has to give one way or the other.

While this is from a very old post (5 years ago, just in reference to advancements in software technology and not anyone's age gap) but would you happen to know or be able to explain why this limitation still occurs when using footage that's been shot in 240 frames per second? Vegas Pro (I'm using 17) still prevents being able to slow it down anymore than a quarter (Down to 60 FPS) and in order to play the video at 30FPS without losing those extra recorded frames, I'd have to render at 60FPS, import the new video file, and then slow it down again to achieve a playback at 30 FPS. While I don't know if this method actually preserves those "extra recorded frames" it seems to be the only way for me to the slow-motion captured at 240 FPS.

Curiously, @UKharrie explained that

With the CX410 Camcorder SlowMo it is possible to slow it further in Studio

But I don't know if they meant below the 0.25 playback threshold.

In any case, I am aware of a number of posts relating to this matter but I haven't found one that actually explains or breaks down why Vegas can't seem to take 240 FPS footage down to 30 FPS automatically. So, I was hoping that, based on your easy to understand explanation and seemingly deep understanding of the way the program works, you would be able to help me understand how the limitation applies in the mentioned particular case. @Chienworks

 

@EditorCP If you are using Vegas pro use the Velocity Envelope.

And keep your framerate factors at exact common factors as you have been doing

Even with the velocity envelope you're limited to 1/12 or 12x. Agreed it's long past time that the software has this limitation removed. There's no reason why the stretch/shrink couldn't be 0.1 to 10, or 0.0000000001 to 1000000000. It's an arbitrary number; let us just type in whatever we want, please.

One feature request i put in ages ago was to set a playback rate per event. In this case, load that 240fps video on the timeline, right-mouse-button click it, and one of the options is 'set frame rate', and you just type in 30 (or probably 29.97002997), or even merely say "match project frame rate". Vegas would then use this user specified frame rate instead of whatever is in the file. The response from the developers was that it would be difficult to keep the audio in sync. Well, if you're doing a speed change that drastic, you're probably not using the audio anyway. So, any event that is video only should allow this. Or better yet, if there is audio attached, the software could ask if you want to attempt changing the audio too, not change the audio, or remove the audio event.

Probably the closest we can come to that is to dump the original file into an image sequence, then import that sequence back into an event. This has precisely the feature i'm asking for, namely, to specify what frame rate to use. Of course, that's only available in the Pro version, not the Studio version, so we're still stuck here.

At least console yourself that by rendering out at 1/4 speed and reimporting, the process gets 4 times faster each time! ;)

@Chienworks see https://vegas-magazine.com/velocity-envelope/ for changes as of VEGAS Pro 14.

https://www.vegascreativesoftware.info/us/forum/any-easy-way-to-speed-up-a-clip-10x-to-100x-i-e-more-than-4x--113924/#ca704103

(I don't expect this to change in VMS/P as they need to keep some "advanced" features exclusively in VPro to "encourage" Studio users to upgrade.)

why Vegas can't seem to take 240 FPS footage down to 30 FPS automatically.

 

Quite easy, just set your project to 30fps and import your 240fps footage at projects framerate. Even VegasMovieStudio can do that

I'm only not sure if this is possible from 240fps to 30fps, because that's slower than max 0.25. But 240fps directly to 60fps must be no problem.

If you are using Vegas pro use the Velocity Envelope

I am using Vegas Pro 17, I will give that a try, thank you. @EricLNZ

And keep your framerate factors at exact common factors as you have been doing

Got it. Thank you! @Musicvid

The response from the developers was that it would be difficult to keep the audio in sync. Well, if you're doing a speed change that drastic, you're probably not using the audio anyway

You're right about the audio @Chienworks

Fortunately, as I later discovered, velocity envelopes will change speeds in the video but not affect the audio, but I only learned that recently thanks to the link provided by @vkmast

Probably the closest we can come to that is to dump the original file into an image sequence, then import that sequence back into an event.

That sounds a bit more like my intended purpose. I've still yet to try the velocity envelopes to slow down directly from the 240 FPS file and feel like your suggestion is much more thorough in ensuring all the frames are used, though I can't imagine the number of images all those frames would be produce haha. >_<

At least console yourself that by rendering out at 1/4 speed and reimporting, the process gets 4 times faster each time! ;)

Alas, you're right.... that's hilarious though! xD

I'm only not sure if this is possible from 240fps to 30fps, because that's slower than max 0.25. But 240fps directly to 60fps must be no problem.

Right, @3POINT that was my entire premise from the beginning. I made a typo with "anymore" (shown below) and maybe what caused your confusion so I apologize but thank you for trying to help.

Vegas Pro (I'm using 17) still prevents being able to slow it down **any **more** than a quarter (Down to 60 FPS) and in order to play the video at 30FPS without losing those extra recorded frames, I'd have to render at 60FPS, import the new video file, and then slow it down again to achieve a playback at 30 FPS.

I also perhaps, may have not made it clear that I'm not merely just hoping to play it at that framerate, but have it actually play each frame from the footage caught at 240 FPS so that it appears as a slow motion segment.

In any case, thank you all for the input and helping point me in the right direction, it's greatly appreciated!

My other NLE can slow down to 0.1x normal speed with sound, no idea why VegasPro and VMS stick to this 0.25x normal speed limitation.