25.00000191 frames per second ???

Moderator: SecondMan

v-empire
Posts: 7
Joined: Wed Sep 03, 2014 9:05 am

25.00000191 frames per second ???

#1

Post by v-empire » Thu Feb 07, 2019 11:50 pm

Hi there,

just found something that puzzles me a bit

Although I´m working with fusion since it exists now I found something strange that I never realized before

If I show the metadata of prores clips that should be 25 fps in my working window

It says 25.00000191 frames per second.

That happens with a lot of quicktime clips in various codecs from various origins, always with prores 444 clips.
It never happens with image sequences and mxf files.

I calculated roughly that it needs clip length of about 5 hours before a frame error would show up

A firend of mine also working with fusion got the same effect (which he also never realized before)

Is this a misinterpretation of quicktime or may it have to do with updates of resolve in the same computer?

Is it a problem at all? Would maybe deinstalling quicktime fix this (but how many clips will become unreadable then even if ffmpg is installed)

Do all the other softwares just clip after two digitits behind the komma, so we just don´t see it there?

Any ideas what leads to this strange behaviour?

Thanks a lot
HolgerHi there,

just found something that puzzles me a bit

Although I´m working with fusion since it exists now I found something strange that I never realized before

If I show the metadata of prores clips that should be 25 fps in my working window

It says 25.00000191 frames per second.

That happens with a lot of quicktime clips in various codecs from various origins, always with prores 444 clips.
It never happens with image sequences and mxf files.

I calculated roughly that it needs clip length of about 5 hours before a frame error would show up

A firend of mine also working with fusion got the same effect (which he also never realized before)

Is this a misinterpretation of quicktime or may it have to do with updates of resolve in the same computer?

Is it a problem at all? Would maybe deinstalling quicktime fix this (but how many clips will become unreadable then even if ffmpg is installed)

Do all the other softwares just clip after two digitits behind the komma, so we just don´t see it there?

Any ideas what leads to this strange behaviour?

Thanks a lot
Holger

cinewrangler
Posts: 21
Joined: Wed Nov 15, 2017 6:47 am
Location: Europe
Been thanked: 6 times

Re: 25.00000191 frames per second ???

#2

Post by cinewrangler » Fri Feb 08, 2019 1:40 am

MOV (and MP4) files store frame-rate as a fraction. For 25 FPS they store 25/1 or 25000/1000 or something like this. As a result Fusion has to calculate the resulting frame-rate using (double-precision) floating point math. The result of that calculation (including potential rounding errors) gets shown as a floating point value.

Actually the MOV Loader could internally test for a number that is "close enough" to an integer number and then add the metadata as an integer number. It would be just a few more lines of code that it seems nobody wrote.
But still, even 29.97 will probably be shown as 29.97002997002997002997002997003 since it is stored inside the MOV as 30000/1001 which does not result in exactly the 29.97 we unprecise humans are used to talk about.

Edit: Fusion displays all metadata entries of the same data type by applying the same rules. Frame-rate is just a float (or integer) value and gets show like all other values of the same data type. Fusion has no extra rules to show frame-rate in a way we would expect in this special case. It doesn't even know that this is a frame rate, it is just a value with a name that happens to be "FrameRate" (and Savers might understand what this implies).
Last edited by cinewrangler on Fri Feb 08, 2019 1:46 am, edited 1 time in total.

v-empire
Posts: 7
Joined: Wed Sep 03, 2014 9:05 am

Re: 25.00000191 frames per second ???

#3

Post by v-empire » Fri Feb 08, 2019 1:44 am

Thanks a lot for shedding some light on this

Best
Holger