I think I've stumbled upon a bug and could use some verification.
In short, I cannot get any Adobe software to correctly output 24fps media to same.
The longer version is that I've got some 24 fps media at exactly 24, not 23.976. Premiere Pro reads the media correctly at 24. (Though on a side note, both Media Browser and Prelude read it incorrectly as 23.98.)
I've created a matching sequence and exported that one clip (no edits, no effects) using both Queue to AME and direct Export from PP. I've also tried the Render Queue out of AE for the same clip in a matching composition. I've also tried Ingest in Prelude with a Transcode.
I've tried exporting to DNxHD, UT, MPEG2-DVD, H.264, H.264 Blu-ray, and JPEG image sequence. The export specs match the 24 fps for all formats.
This was tested on both Windows 7 and Windows 8.1.
In every single case, brining that exported media back in and placing it directly over the original, the frames to not match. The audio is perfectly in sync, the durations are correct down to the frame. But as I move through the footage, the frames begin to mismatch, so that if I click the eyeball to turn off track 2 and see the original underneath, it's a different frame! They start off identical, and they end up syncing again near the end so there's no duration discrepancy. But the frames in between do not match!?!?!?
This does not happen with my 23.976 media, only with the 24 fps media. It does seem to take some time for the drift to pronounce, like 5 to 10 minutes of media. It didn't show up on shorter clips.
The clip tested was spanned into two files, so I wonder if that plays a part.
Can anyone with genuine 24 fps media test this? It's a pretty serious bug if such media will not export frame accurate.
Exactly what media (camera footage / codec) are you using in your test?
I am guessing maybe your hacked GHx ?
Haved you tried anything else?
Whats the issue if...
The audio is perfectly in sync, the durations are correct down to the frame.
They start off identical, and they end up syncing again near the end so there's no duration discrepancy. But the frames in between do not match. WTF!
Sounds like a GOP preview type of thing .
It is from a hacked GH2. It's the only camera I have access to that can record genuine 24 fps. All the others do the faux 23.976, which does not produce the error. I need someone with RED, Alexa, BMCC or other such 'high end' cameras who might have some 24 fps footage to test with.
The footage is I-frame only, so GOPs do not play a part.
I interpreted some 23.976 as 24fps in Ae and exported it to 24fps. Premiere Pro sees it as 24fps.
I repeated the 9 second clip over and over to achieve a 20 minute sequence which I am exporting to H.264 now. When it is finished, I will bring it back into Premiere and see how they line up.
If they are identical, you will need to provide footage or find someone who has some. But if this test shows a discrepency, then Adobe will have an easy way to replicate the problem.
My test failed to replicate the issue.
So, footage produced in After Effects comes out 24fps according to Premiere Pro and exporting it and bringing it back in revealed no issues.
So there must be something about your footage.
Dum phones don't (mine).
Back in my days working on OnLocation, I often tested timecode-related matters by shooting footage of both a stopwatch and a mirror showing the camera's LCD flipped forward, with the timecode on.
Not particularly relevant to this thread, but when I was checking for dropped frames nothing beat shooting a pendulum like this.
And my favorite trick for testing audio sync: snapping clothespin in front of the camera every few minutes. On playback, there was no mistaking the frame when it snapped and the spike in the audio. When retrieving the C47 from wherever it flew became tiresome, I even rigged one up with a short strand of monofilament that I'd loop around my finger.
Some more data:
I shot a stopwatch and tested.
What I found was that the export was largely correct, except for the last few frames. The error was PP not reading the file correctly for display in the sequence. Every now and then, PP would repeat and/or skip a frame. This repeat/skip is what was throwing off the match between original and export. Ironically, the export seemed to be frame perfect, except for the last few frames, which PP had to fudge in order to get the 'correct' duration. I put correct in quotes because the original was actually 4 frames longer than it should have been due to the repeated frames.
So the question becomes, why is PP reading the file correctly for export, but not for display in editing? That's messed up!
Could it simply be a long GOP issue? That the preview is screwing it up? Have you tried changing your preview file codec? Does that codec even matter if you don't render?
Sorry. More questions and no answers.
The footage is I-frame only, so no GOPs. Preview codec wouldn't matter without creating a preview file. Though since the export seems to be frame accurate, I wonder how a preview would turn out...
I did find that even a three minute clip produced the issue, so if anyone out there has real 24 fps footage, I'd love some confirmation on this. At this point I don't know if the problem is my footage, or PP's handling of all 24 fps footage.