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

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.

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.