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Sync problems using Premier DAW Software
Old 12th January 2018
  #1
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Thread Starter
Sync problems using Premier

I've followed the similar threads here on this problem already, but I'm still going to put this out there:

The video editor is using Premier Pro.

We are editing/mixing the audio.

They send us the following:

OMF Files along with the audio files
mp4 with audio

Over the course of the 22 minute (in this case) piece, audio in both the OMF and the mp4 audio drifts in and out of sync with the mp4 video.

Because the OMF audio and the mp4-attached audio are in sync with each other, I presume that this has to do with the video export from Premier. Some of my theories include video drift during fades/crossfades/transitions, OR the use of video pieces that were shot with different frame rates.

Does anyone have any experience with this? Any other ideas as to what it might be?

The interesting thing is even if we disregard the video, our audio still drifts in/out in relation to the video once we send them our mixed files. PS., yes, we have the proper frame rate chosen in PT.

Thanks for any suggestions!

John
Old 13th January 2018
  #2
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Ask for a better format than a mp4. Something that doesn't use interframe compression. Preferably either DNxHD or Apple ProRes

Quick test, if you watch the original mp4 with embedded audio on a laptop in quicktime player or on a phone, does it stay in sync? Now in Pro Tools if you do the import audio from picture and watch it lined up to the picture, does it now drift? If so, your system is having trouble decoding the video. Increasing video offset can take some of that burden off. And a better video codec used will definitely help.
Old 13th January 2018
  #3
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Thread Starter
Quote:
Originally Posted by pentagon View Post
Ask for a better format than a mp4. Something that doesn't use interframe compression. Preferably either DNxHD or Apple ProRes

Quick test, if you watch the original mp4 with embedded audio on a laptop in quicktime player or on a phone, does it stay in sync? Now in Pro Tools if you do the import audio from picture and watch it lined up to the picture, does it now drift? If so, your system is having trouble decoding the video. Increasing video offset can take some of that burden off. And a better video codec used will definitely help.
First off, thanks for your response.

If I simply play the mp4 in Quicktime, even the embedded audio drifts in and out of sync, which is the same thing that happens in ProTools. This is why I suspect some problem in the video export from Premier. The mp4 embedded audio drifts in the same places that the OMF audio files drift.
Old 13th January 2018
  #4
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Jeff Hayat's Avatar
 

It's possible that the drift is due to vid speed vs film speed. The diff of which is 1.44 frames per min. Go down to 10 min, and (you will have to determine the direction) move the audio 14(15) frames. Is it in sync? Yes? Go down to 20 min, and move the audio another 14 frames. Is it in sync? Yes? You have now found the problem.

Even tho there may be no film involved, it is possible someone did an export with pulldown on, when it should have been off, or vice-versa.

Cheers.
Old 13th January 2018
  #5
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Thread Starter
Quote:
Originally Posted by Jeff Hayat View Post
It's possible that the drift is due to vid speed vs film speed. The diff of which is 1.44 frames per min. Go down to 10 min, and (you will have to determine the direction) move the audio 14(15) frames. Is it in sync? Yes? Go down to 20 min, and move the audio another 14 frames. Is it in sync? Yes? You have now found the problem.

Even tho there may be no film involved, it is possible someone did an export with pulldown on, when it should have been off, or vice-versa.

Cheers.
Thanks, Jeff.

Unfortunately, it's not that "predictable". For instance, I'm 7:30 into a 22 minute project. And an entire 20 second audio section is way ahead of the video (like, 10 frames), then the very next section is in sync.

So while I think your idea may come into play on other projects on which I've had some question, I don't think it's the solution with this particular problem...

Thank you!

J
Old 13th January 2018
  #6
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Jeff Hayat's Avatar
 

Oh, I was under the impression that the entire thing was drifting gradually.

If parts are drifting, then parts are in sync, then parts are drifting, that could mean that the vid speed vs film speed comes into play with parts. Which would be strange, but not completely out of the Q. If that's the case, the vid ed. would have to fix that.

One other thing that comes to mind is a clocking issue. Is everything referenced properly (w.clock/blackburst) on their end and yours?

Finally, maybe you want to ask the vid ed. for a screenshot of the Prem. export window, and make sure that the standard (PAL, NTSC), frame rate, and anything else that is relevant are all correct. Is it possible to have Prem. set to "free" (for lack of a better term)? ie - where it wouldn't export at a particular framerate/standard, but instead it would just export to an internal reference?
Old 13th January 2018
  #7
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Thread Starter
Quote:
Originally Posted by Jeff Hayat View Post
Oh, I was under the impression that the entire thing was drifting gradually.

If parts are drifting, then parts are in sync, then parts are drifting, that could mean that the vid speed vs film speed comes into play with parts. Which would be strange, but not completely out of the Q. If that's the case, the vid ed. would have to fix that.

One other thing that comes to mind is a clocking issue. Is everything referenced properly (w.clock/blackburst) on their end and yours?

Finally, maybe you want to ask the vid ed. for a screenshot of the Prem. export window, and make sure that the standard (PAL, NTSC), frame rate, and anything else that is relevant are all correct. Is it possible to have Prem. set to "free" (for lack of a better term)? ie - where it wouldn't export at a particular framerate/standard, but instead it would just export to an internal reference?
Jeff, thanks for the good thoughts.

Yes, vid speed vs film speed could be in play, this is a TV show shot in various locations, and while I presume the same crew and setup were used, I couldn't say that with 100% certainty.

Clocking: I've tried clocking to the Sync IO Internal feeding WC to all devices and I've also tried clocking the Sync IO itself to a Blackburst Gen. All the same result.

As far as Premier, I don't know the program AT ALL. But because even their embedded audio drifts in and out with its attached video, and because their embedded audio seems to line up with the audio files within the OMF file, I do believe it's something in Premier's export that yes, could easily be a preference that they have set incorrectly. But asking them for a screenshot of the export window seems like a good idea, so I can at least look for any obvious problem.

Thank you!

John
Old 13th January 2018
  #8
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Thomas W. Bethe's Avatar
Quote:
Originally Posted by pentagon View Post
Ask for a better format than a mp4. Something that doesn't use interframe compression. Preferably either DNxHD or Apple ProRes

Quick test, if you watch the original mp4 with embedded audio on a laptop in quicktime player or on a phone, does it stay in sync? Now in Pro Tools if you do the import audio from picture and watch it lined up to the picture, does it now drift? If so, your system is having trouble decoding the video. Increasing video offset can take some of that burden off. And a better video codec used will definitely help.
I think this is probably it. The MP4 just is not working.

You did not say whether you were on a Mac or PC. Can you let us know which, sometimes there are problems that are specific to a computer type? Thanks!
Old 13th January 2018
  #9
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jwh1192's Avatar
but didn't the OP say this "If I simply play the mp4 in Quicktime, even the embedded audio drifts in and out of sync"

this means the editor moved the Video out of Sync in certain sections - either by mistake or accident .. or am i reading this wrong ..

is the audio actually changin or is it the Video that is the culprit ???

this reminds me of another Thread recently .. either here or at the DUC .. if this is the same project, the OP there had mentioned it was talking heads .. i have seen this is music oriented videos where the editors messed up lipsync because they were trying to cover something up ..

curious if this is the same project .. or different .. if different we need to educate another group of editors !!! haha
Old 13th January 2018
  #10
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Based on what the OP says the editor is going to have to export again. I'd also recommend that you try AAF from Premiere, it seems to have fewer oddball issues like this. The smoking guns I see are 1: that some areas are in sync and some are not (but not a continual drift or a sudden jumping out of sync that stays out) and 2: that in some places the picture file is out of sync with its own audio track. Another thing to mention to editorial: make sure that the sound track of the video file they give you is at 48k. I've had some similar issues with video files sent to me that turned out to have audio @ 44.1.
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