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Timecode issue: Exported length not matching project length. Matches if I bring it back in

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Ryan Ritchey
Timecode issue: Exported length not matching project length. Matches if I bring it back in
on Dec 18, 2017 at 4:01:10 am

So I've edited a 23.98 project (with 23.98 source) in FCP X that is exactly 1:05:00:00 on the timeline. But when I export the project, and play it in QuickTime, or Mpeg Streamclip, the playback length is 1:05:04:00: four seconds longer.
I figured this was an FCP X issue, so I brought the file that said it was 1:05:04:00 in Quicktime into Premiere CC 2018. Lo and behold, it was 1:05:00:00 again just like in FCP X. However, when I export from Premiere, the same thing occurs: the exported file is 1:05:04:00.

When I look at the file properties in Premiere, the frame rate shows 23.976 and duration of 1:05:00:00. But lower under video track 1 it shows a duration of 1:05:03:21 and frame rate of 23.98, which seems to be the heart of the matter, but I don't know how to get these numbers to agree.


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John Pale
Re: Timecode issue: Exported length not matching project length. Matches if I bring it back in
on Dec 18, 2017 at 5:17:30 pm

Its the timecode thats messing you up.

The timecode is counting at 24 frames pers second. Your video is running slightly slower.

In NTSC, this discrepancy (timecode runs at 30 fps, but video is 29.97) is fixed by using drop frame timecode. Unfortunately, in the 23.976 realm, there is no drop frame timecode. So you have to live with the discrepancy between timecode and real time and plan accordingly.


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Paul Carlin
Re: Timecode issue: Exported length not matching project length. Matches if I bring it back in
on Jan 4, 2018 at 6:53:29 pm

23.976 and 23.98 are the same thing. 23.98 is the rounded off version of 23.976. The difference between the two would not explain 3.8 seconds of discrepancy.

The difference between 29.97 and 30 fps over the duration of an hour is 3.6 seconds. The same would be true for 23.976 vs. 24 fps as these are derivatives of 29.97 and 30 fps. Meaning that 23.976 only exists because 29.97 exists.

Drop Frame timecode is a way of dropping frames to accommodate for the 3.6 seconds lost over the course of an hour of real-time playback. In broadcast video (AKA color NTSC and everything that followed), there is only ONE playback speed and that is 29.97 frames per second. To have the timecode match "real time" as close as possible, certain designated frames were "dropped" from the time code counter (NOT from the actual playback video!).

To get to the point... it appears that your problem is related to the interpolation of the playback rate in the different applications. The difference between 23.976 and 24 fps would explain the 3.8 seconds of discrepancy you are experiencing. The actual playback is a completely different story.

The real question is, what is your deliverable? How will the video actually be played? And what is the true frame rate of the playback mechnism?


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Jeff Pulera
Re: Timecode issue: Exported length not matching project length. Matches if I bring it back in
on Jan 4, 2018 at 8:58:33 pm

23.976 frames per second x 60 seconds per minute x 65 minutes = 93506 frames of video

24 fps timecode x 60 x 65 = 93600 frames

93600 - 93506 = 94

94 / 23.976 = 3.92

The math adds up, accounting for 24fps timecode versus 23.976 actual frame rate as mentioned earlier

Thanks

Jeff

Jeff Pulera
Safe Harbor Computers


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