Using 23.976fps in a 24fps timeline. Must I Modify-Frame Rate?

[ST!LL FR@NK]

Hey, Y'all. I am editing a full length documentary at 24 fps. Very late in the game, 23.976fps footage was delivered to me. I am freaking out. A lot of it is already in the timeline - up until I deicovered the fps difference.  Do I need to deal with this? Half of what I see says Premiere automatically interprets it as 24fps because that is the sequence rate. 1/2 says it absolutely does NOT. What is the truth? Bottom line: Can I use the 23.976 footage as is? Or not? And how do I fix this? I assume I just lost a day's work if I have to fix it, because Modify - Frame Rate can only be done in the bin. HELP!

[R Neil Haugen]

This can be a right puzzlement ... as most "24fps" is actually 23.976 anyway. I do know that many editors don't worry about any difference between them. And Premiere normally handles it pretty well.

You could download the free utility MediaInfo, and then drag/drop a clip onto it's icon on your desktop. When it launches, select the "Tree View" to see the data. Most of the "24fps" I've ever used has been listed at the actual math for 23.976.

[ST!LL FR@NK]

Many thanks for your response. Like so many things in Life, this is ultimately an onward, upward, hope for the best scenario, it seems 🙂

[Remote Index]

Hi ST!LL FR@NK,

When the project panel lists media or sequences as 24fps or 23.976fps, it means your media or sequence is actually 24fps or 23.976. There is no ambiguity there.

Half of what I see says Premiere automatically interprets it as 24fps because that is the sequence rate.

No such automatic interpretation happens. Premiere Pro plays 23.976fps media at 23.976 fps and displays 23.976fps sequences at 23.976fps.

1/2 says it absolutely does NOT.

This is the half that is correct.

Can I use the 23.976 footage as is?

When you have any sort of frame rate mismatch - where the media does not match the sequence frame rate - then Premiere Pro performs a frame rate conversion in the timeline: the media clips in the timeline are transformed to match the sequence frame rate.

There are 3 versions of this:

PREMIERE PRO FRAME RATE CONVERSIONS - 3 OPTIONS

A. "QUICK AND DIRTY"

If you simply drag your clips into the timeline, Premiere Pro does what I call a fast and dirty frame rate conversion. It will simply duplicate (or drop) frames to acheive the necessary frame rate. (You may need to render).

B. "FRAME BLENDING"

If you right-click on a clip in your timeline and choose "Clip Speed/Duration" you will see options for "Time Interpolation" at the bottom of the dialog. The above "quick and dirty" method is the default (known as "frame sampling" here). The second option is "frame blending" which does what it says ... combining or blending frames to create new ones. You probably have to render the clip after.

C. "OPTICAL FLOW"

This is the third option in the dialog. This option uses software magic to analyze existing footage and create new frames as necessary. You will likely need to render the clip after. Depending on the footage, it will either be amazing or heavily artefacted (unusable) or somewhere in between.

In practice, the two frame rates are of course very close - between 23.976fps and 24fps, there is only 1 frame difference for every 1000 frames. That means if you have clips in the timeline less than 1000 frames in duration, you're not likely to see any "frame rate conversion". For longer clips, you'll be able to track where the frames are doubled for 23.976fps media in a 24fps timeline (every 1000 frames) in a "quick and dirty conversion". This may be sufficient for your needs.

The other way to handle all this would be to "Interpret Footage" before you use it in the timeline - effectively speeding up your 23.976 material to 24fps. (Note that Adobe does not support use fo "interpret footage" with its built in proxy workflow.)

One way of working would be to ignore the frame rate conversion while you edit (relying on the "quick and dirty') and then once you have picture locked, deal with material on a clip by clip basis - either refining the frame rate conversion, or going back to source clips and using "interpret footage" to correct the frame rate and re-cut it into the timeline (allowing for slight differences in media on the new, interpretted footage).

R.

[ST!LL FR@NK]

Thank you for responding. There is only a VERY small chance that the 23.976 footage will end up longer than 41.7 seconds (23.967frames :1sec::1000 frames : xseconds.  x=4.17seconds).  20 seconds would be long in this context, in fact. To be certain, I will never allow this to happen again! LOL What a headache. So far, so good, and you have provided further understanding and reinforced teh veracity of a few potential courses of action. Gratitude! Hopefully the need does not arise for deep surgery. Fingers crossed. Cheers!

[R Neil Haugen]

Excellent post on Pr's practices in applying media in mismatch situations. Clear, concise ... and usable.

My only difference with the post would be ... what's defined as "24fps" versus "23.976" ... and it's a practical point.

Both from personal experience, and from the colorists I work with, this is often a roll-your-eyes situation.

A couple cameras I've got say 24fps as a recording speed. They actually produce 23.976. One says 24fps, actually produces 24fps. This is sadly not unusual. Oh, and one actually says 23.976, and yes, it's actually 23.976. Splendid.

So any multicam shoot I do will have both 24fps and 23.976 fps involved.

I've had users send me clips to test, where the file header actually says 24fps. But in reality, the file was 23.976.

And if the app reads the file header, well ... it lists it as 24fps when it ain't.

A right freaking mess. And from my many colorist friends, this is unfortunately way too common. And can add hours to a conform at times.

[ST!LL FR@NK]

I'm not sure what a file header is. I am assuming I can trust what the meta data says once imported via Media Browser. Is that an accurate assumption? Do you think I am OK as is if clips remain under 40 seconds? Almost certainly under 30. And most often under 20 seconds, or roughly 500 frames? Gratitude for your insights!

[R Neil Haugen]

The file header is what any computer file starts with ... it tells the computer what's in the file. All the meta and such.

For your usage, as R says, this is probably not going to be an issue, as long as you stay to decently short cuts.

[Remote Index]

R Neil Haugen,

"And if the app reads the file header, well ... it lists it as 24fps when it ain't.."

Do we know this (header file metadata) is what is being displayed by Premiere Pro?

Anyone?

Edit for follow up question:

"the file header actually says 24fps. But in reality, the file was 23.976"

How did you determine the frame rate "in reality" if the file header was incorrect?

R.

[R Neil Haugen]

Checking with MediaInfo, Bridge, or Resolve.

[Remote Index]

R Neil Haugen,

I'm curious as to why you trust the fps listings of these tools over Premiere Pro.

R.

[R Neil Haugen]

Experience. And the experience and wisdom of other high-end video post folk, most colorists, for whom conform data is crucial. And is either right or wrong.

Premiere typically follows the "listed" header number. Others can show the actual file data.

I've worked with a camera that showed one number in Premiere, another in Resolve and MediaInfo. And that showed one in Premiere and Resolve, another in MediaInfo.

So ... what is "right"?

[Remote Index]

So ... what is "right"?

I guess that is what I was asking - how you came to determine what was correct, given conflicting information from different tools.

But aside from that, this is another case of poor documentation - we don't know what Premiere Pro is displaying in the FPS column, because Adobe doesn't want to tell us.

R.