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Automatic Duck Pro Import FCP - Avid to FCP audio sync issue

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Dillon Brown
Automatic Duck Pro Import FCP - Avid to FCP audio sync issue
on Nov 3, 2011 at 3:37:20 am

I've search high and low for anyone encountering a similar issue, but to no avail. I'm extremely interested in finding the reason for this incredibly odd situation.

Using Pro Import FCP I was able to successfully import an Avid AAF into Final Cut Pro, and the FCP sequence is nearly perfectly identical to the Avid sequence. A few quick notes about the Avid project
- cut in 1080p/24 with a mix of RED and 7D footage
- all audio synced in Avid and used in the sequence
- a bunch of sound effects also imported that I don't have the original imported files for

My original plan was to use the Automatic Duck "use existing media" function with the "use original imported graphics" box checked. I tried this and it found all the original transcoded quicktime files perfectly - video track is fantastically translated. However, sound is a bit of an issue. I realized that using this function wouldn't work on all the audio clips, because I don't have the original audio files for a lot of the sound effects and temp music. In that case, I'd have to uncheck the "use original imported graphics" box and have Automatic Duck create quicktime reference files pointing the original mxf files in the Avid MediaFiles folder.

This is where the plot thickens.

For the sound effects and temp music Automatic Duck was able to find, they are perfectly in sync, like the video. However, for the original on-set recorded sound, the sound is completely out of sync. I thought that perhaps it was out of sync identically in every clip - nope. One clip for example is 2:14 out of sync, another 1:10. When I opened one of the audio clips in the translated sequence in FCP and looked at the timecode in the viewer window, the In-point does not match the In-point of the same clip in the Avid sequence. The timecode discrepancy is not the same in the Avid sequence as the length of the different in the FCP sequence.

I also imported all the original wav files into FCP and looked at their durations and start times. The most interesting piece of the puzzle is that, when comparing to the same files imported into Avid, most of them are the exact same duration. However, every few wav clips are different by a few frames. Some longer in Avid, some shorter in Avid (and vice-versa for FCP). Therefore, the starting time for the timecode of the clips shifts slightly.

I had assumed that the timecode for the start times of the clips would be hard coded into the wav files themselves. But in FCP it is appearing that this isn't the case - that the start time of the clip is dependent upon when the last clip ends.

I assume this may be due to NDF vs DF perhaps? I attempted to re-import the audio files into Avid and changing the import settings for DF, but the clip durations still remained the same.

What's baffling is that the durations aren't all different - some are the same in FCP and in Avid, and some are not.

Therefore, the start times of the clips in FCP are thrown off entirely, getting further and further apart from the same clips in Avid, and the reason why when Automatic Duck re-links to the original wav files they are thrown way out of sync. I would assume that if was a simple solution like NDF vs DF, or sample rate, at least the duration of the files would remain the same in Avid and FCP.

Now a few more notes about this situation.
- it appears that the Avid sequence is set at 24 fps. However, our RED footage is at 23.98... this may be the culprit to the issue
- when using Automatic Duck Pro Import it reports after importing the XML that the project timebase was changed from the AAF 24 fps to 23.98, to match the FCP sequence preset
- all the original on-set recorded audio is in wav format at 48.000 Khz sample rate

What I also don't understand is why the editor set the project fps to 24 instead of 23.98. I also don't understand if editing at a 23.98 timebase with 48.000 khz audio will be an issue, as doesn't the audio need to be pulled down 3:2? Or else recored at 48.048 Khz on set?

As of now I'm just having Automatic Duck re-link to the original RED and 7D quicktime files, and having all the audio re-link to the Avid mxfs.

Pardon the ignorance and long post with multiple facets. Any input would be so fantastic. Thanks!

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