60p into 24p for slow motion

Patryk Rebisz wrote on 5/12/2008, 2:12 PM

I have some footage that was shot 60p (not 60i) that i want to convert in 24p timeline into slow-mo. I was wondering if all i have to do is dump the 60p footage on the timeline and stretch it 2.5 times.... Will it work???

Comments

johnmeyer wrote on 5/12/2008, 2:25 PM

I assume you have tried it. If not, try it and see what it looks like. Should only take a few minutes to render a test clip.

I would think you would get spectacular results. If there is a problem with the result, let us know the nature of the problem and we can go from there.

farss wrote on 5/12/2008, 2:39 PM

The trick is to make certain you stretch it to the exact same number of frames. That way there's no way Vegas will resample it.

Bob.

rmack350 wrote on 5/12/2008, 3:52 PM

What would happen if you exported it as an image sequence from a project that matched it's 60p settings, then imported the stills as a sequence into the 24p project?

Rob Mack

fldave wrote on 5/12/2008, 4:00 PM

I would try both precise stretching and the image sequence for a sample timeline and compare. Image sequence would definitely preserve the intended rate, but the stretching may save a lot of time/disk space.

farss wrote on 5/12/2008, 4:24 PM

Both will work and should produce the same result. If they don't you've done something wrong.

Switch project to match shooting fps (60). Switch Ruler to Frames. Note length of clip in frames. Change Project to target fps (24). Ctl Drag event to same length in frames read by the ruler. Job done. Make certain it is exactly the same number of frames.

Bob.

Tim L wrote on 5/12/2008, 4:32 PM

Can't you just right-click on the event, select properties, then set playback rate to 0.4? (ie 0.4 x 60 = 24)

To get the full event length, then, you just need to drag the end out (not ctrl drag). Otherwise, if you have 10 second event, and set playback to 0.4, it keeps the event 10 seconds long. You would need to stretch it out longer to see the original full 10 seconds of video.

farss wrote on 5/12/2008, 4:50 PM

You'd think so however I'm simply repeating the method recommended in a very old white paper from SCS on how to go between 24fps and 25fps. The advantage would seem to be that there's no risk of rounding errors causing resampling. For example 30p is most likely not 30.000 fps and nor is 24fps 24.000 fps and and any error, even at the nth decimal place and you could get the odd wierd frame.

Bob.

johnmeyer wrote on 5/12/2008, 6:03 PM

I must be missing something (which is not unusual for me ...)

Why not set the playback rate (right-click on the event to get to this setting) to the correct ratio and then do a regular drag of the end of the event? It seems like that would guarantee you'd get the correct rate every time. So, to take the simplest slow-down, you'd set the playback to 0.4000 (24/60), and then drag the edge of the event to make it 2.5 times longer.

I would also set the event resample to "disable." That way, Vegas will not resample, no matter what. If somehow you end up with a ratio that doesn't give you integer decimation (which is what I think we're trying to achieve), it will simply duplicate or drop a frame once in a great while which, most of the time, won't be noticed (although sometimes it will).