24 fps video for 25 fps final output - Sync'ing issue

[antonis]

Hello all

I am currently working on a short film and I have been having major issues with the sync'ing of the OMF and the video file.

Some keyfacts:

• The picture was shot in 35mm
• I have no idea what happened at the telecine progress
• The file I received is a 24 fps DV-PAL video file. Please check screenshot of the file here.
• Avid was used to cut the film and the sequence setting are in 24 fps
• The OMF that was exported is in 24fps.
• The location recordist used a Nagra V and I was told he recorded in 24 fps.
• But the final format would be in 25 fps to go either on Digibeta or HDCAM SR.

In the screenshot you will notice two different BITCs. The one on the top is running on 25 fps and on the one on the bottom is running in 24 fps.

The problems that I am facing are these:

1. When I set up the Protools session in 24 fps sound and picture drifts (but please don't try and comment on this point but try and see the next argument - or leave this last. )
2. When I change the session to 25 fps, the audio is out of sync. It doesn't drift, it is just out of sync. So, I can manually bring it into place (it is about a one second off ) but I don't call this a solution.
3. Check out this video here.

This is a screen recording of what happens to the Protools timeline. To put it in words, what happens is that there is a frame added to the picture every one minute. Which means: the video starts at 10:00:00:00, moving the playhead a frame forward does not correspond to a frame change in any of the two BITCs (sorry, BITCs sound a bit dirty ). Instead, when the playhead moves another frame this when the BITC starts rolling. The same things happens at 10:01:00:00 (in the video I hesitate a bit at that point) and then at 10:02:00:00 and so on. As a result, there is a 1 frame added for every minute on the 25 fps clock but because of the frame discrepancy with the 24 fps one the Protools timeline remains constantly a frame ahead.

Would anyone know why this happens. Please - no offence - but I would like an expert opinion here as I have spent quite a few days trying to sort this out! (and I have started looking like this ----> )

[Frank Kruse]

Why on earth did they shoot 24 all the way when the release is on a 25fps media and not cinema?

switching the session from 24 to 25 or back only changes the tc ruler. it doesn't affect sync at all.

I assume either the info about the workflow is wrong our they gave you a wrong QT with duplicate ghost frames which is not necessary. You should use a true 24fps DV PAL.

Your audio is correct, it's the QT that is wrong.


frank.

[Frank Kruse]

Regarding your example video:

first you have to make sure you spot the video to the timeline correctly. As you can see the changeover to frame 01 is already off by 1 frame because you didn´t spot the last frame showing 00 to your timeline.
Secondly you have your session set to 25fps but your video is 24fps. Set the session to 24 before spotting the video to the timeline.

My guess is that the top TC is the correct one. Spot the QT correctly and you should be fine.

Since it´s a 24fps project use that TC ruler not the 25fps one!

Frank.

[I hear voices]

Frank is right you don't spot the video to the timeline correctly. And set your session on 24 fps all the materials are 24. why you se it on 25? And the burn in TC you have to see is the 24fps. After that if the audio and picture are still out of sync ask for a correct QT video. Is the avid project is set to 24 and is sync you have to be sync too.
An other easy thing you can do to be sure if everything are all right between Avid and Pro Tools see the time length of audio and video from pop to pop in both platforms (time not frames).
It's not the time to think about the 25fps copy of the film yet. Don't change frames on project cause all the materials and Avid are on 24.
The changing from 24 to 25 takes place after the negative cutting or at film scanning so then you have to pull down 4% or just pitch down 4% your final mix, it depends what are they going to do from the printed or scanned film to beta or hdcam.