Inspiring

Question

Still duration timing problem

Forum|Forum|3 years ago
March 4, 2023
3 replies
1644 views

I was working on some stop-motion video and I noticed that the timing wasn't matching outside references. Specifically I had set the still image default duration to 0.5 seconds. This should have matched a metronome speed (or music beat) of 120 BPM. But it would get noticably out of sync after just a few beats. So I made a test video with just 4 images of "1", "2", "3", and "4" repeating in a loop. And I found that the stills were advancing at approximately 129 stills per second! This is much faster than I can account for with a 0.5 second still duration.

My frame rate is 29.97 fps so each still should last 14.98 frames. But the difference between my expected 120 stills per second versus the actual 129 stills per second is more than you could account for with just rounding error in the framerate. So what am I doing wrong? How do I get my stills to march out at a specific expected rate?

Thanks in advance.

Error or problem

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MyerPj

Community Expert

<<for example the default transition duration seems to be stuck at 2 frames, but if anything wouldn't that add time, trather than speed it up?>>

No, the time is set by the length of the clips next to each other. You could have to 5sec clips next to each other and the time is 10 seconds. If the clips were stills or video with extra frames (head/tails) you are cutting off (at least where they join) then you could add a transition and it doesn't change the length of the sequence / timeline. Just what's showing.

<<shouldn't be mathematically deterministic>> Be an artist/editor too.

Ann Bens

Community Expert

Dont forget to set

to desired framerate.

Default transition duration is not stuck at 2 frames it is the minimum requirement to set a double sided transition.

P

peternelsonAuthor

Inspiring

How exactly does Intermediate Media Timebase affect this?

In general, I've had a hard time getting clear answers to anything about timing in Premiere Pro. Out there on the web there's a lot of "folk culture" about things like this ("try this", "try that"), but there's no reason why it shouldn't be mathematically deterministic: If I have a set of still frames that I want to render at a precise rate (so they match a musical beat) it should be straightforward to compute the settings based on fps, still-duration, transition duration, timebase, etc. Where can I get some precise information on this?

Ann Bens

Community Expert

Still images don't have a framerate just a duration.

In video 1 frame is the limit.

In audio you can go as far as 1/48000 of a second.

the higher you set your sequence framerate the smaller 1 frame in time gets and the more accurate you can edit to the beat.

Sorry Intermediate Media Timebase is for still image sequences only (it sets the timebase).

R Neil Haugen

Legend

First, nothing can be in partial frames. So a still can be 14 frames, it can be 15, but it cannot be 14.98 frames.

Any particular reason for the 29.97 sequence?

Neil

Everyone's mileage always varies ...

P

peternelsonAuthor

Inspiring

29.97 fps is a standard broadcast frame rate in North America so I just took the default. But as I said, a fraction of a frame is not enough to account for the error. 29.97 fps is also a standard camcorder speed - if you were recording a 120 BPM metronome on a camcorder it wouldn't speed it up or slow it down by much.

How reliable is the Still Duration setting - is it just a nominal figure or is it meant to be precise? I can imagine things that would slow it down - for example the default transition duration seems to be stuck at 2 frames, but if anything wouldn't that add time, trather than speed it up?

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