Bounce to Disk, import to FCP - bizarre sync issue

[smack5099]

Hi all,

I've been having so much fun agonizing over this issue I thought I'd let some other people join in the fun. Okay, really, I've got a bounced AIFF file from Pro Tools that doesn't stay in sync when it goes to FCP.

There's a lot of information to cover here, so bear with me.

1) The project is a 123-minute feature. It's made up of 9 separate sequences (which correspond to nine different Pro Tools projects). This problem only occurs on 1 of these 9 sequences. Over the course of about 14 minutes, the audio is about 20 frames shorter than the video. (I know what you're thinking, but there's no pulldown or pullup anywhere. I've checked this extensively.)

2) When I export the video for this sequence from FCP and import it into the Pro Tools project, it syncs perfectly with the Pro Tools audio. No problems whatsoever.

3) This sequence worked fine until recently. It may be worth noting that I had more or less finished this project and left it for a period of a couple months before revisiting it to make the finishing touches, and it's only after revisiting it that the problem has occurred. It may also be worth noting that I had actually done a quick add-on record/edit on this particular sequence at some point during the down period (I needed the sound of footsteps in the snow, so I went and got the sound one day when it snowed, positioned it in the project, mixed it, etc. but then held off bouncing until now).

4) The source is film, and everything - EVERYTHING! - is in 24fps (true 24fps, not 23.98). I've checked the settings in FCP and Pro Tools a million times to confirm that I'm not crazy. It's 24, 24, 24, 24 all the way through. It's also 48K, 48K, 48K, 48K everywhere as well (again, no pulldown or pullup).

5) Something bizarre I noticed that I thought would be the source of the problem, but changing it ended up doing nothing. All the sequences were set to internal clock source. Somehow or another, when I looked at the Session settings for this particular sequence, the clock source had been set to SPDIF. I have no idea how this happened. I don't have any external clock source. At any rate, I changed it back to internal, but that didn't change anything. Still drifts by the same amount.

6) Like I said everything is 24fps/48K. Except that this AIFF file, when it goes to FCP, FCP thinks it's 30fps drop-frame. All the other bounced AIFF files go into FCP as pure 24. This one, despite the fact that I'm doing nothing difference, shows up as 30fps drop-frame in FCP. (Again, this is despite the fact that it's in pure 24fps in Pro Tools.)

7) Okay, here's where it gets really bizarre. The info on this AIFF file, shows the correct duration both in Finder and in FCP. The duration in 24fps is 13:51:15. FCP shows 13:51;19 in 30fps which matches up pretty much perfectly in terms of actual length. It's when I drop it into the sequence that it's off. I suspect this has something to do with putting audio with drop-frame TC into a pure 24fps sequence, but I have no idea how it happens. (How would FCP change the rate of the file for the 24fps sequence without any rendering involved?) Furthermore, I opened the file in peak and it shows all the proper parameters: 24fps, 48K. Only FCP doesn't understand this, and only for this one file out of the nine. (I know I keep saying "the file," but I assure you I've bounced many, many, many of them by now in my troubleshooting.)

Naturally, I suspect it's an issue with FCP, but figured someone here might be able to lend assistance. What I really don't understand is why this issue would occur with only this one sequence while the others work perfectly. Like I said, there are a couple things unique about this particular sequence (having worked on it a little in the interim and discovering the clock source to have been set to SPDIF), but I don't see how that could lead to this all of a sudden. At any rate, I'd say it's pretty clear that whatever is making FCP read the file as 30fps drop-frame is what's causing the problem, and that if it understood the file as a 24fps file, the problem would almost certainly go away.

For what it's worth, it appears that I can bounce to a Quicktime movie, and that audio will sync up fine, but, well, I'm just not satisfied with using that workaround permanently. Any help is greatly appreciated. Thanks.

[Sonsey]

Hi Smack...

No you're not crazy... you've found a "feature" of FCP. When working in TRUE 24fps on FCP if the capture settings are set to 29.97 before the sequence is created (and odds are they are), then FCP will treat all incoming .aiff and .wavs as if they need to be pulled up to compensate. The solution to this problem is to open your file in QTPro then save it as a Quicktime movie with audio only at 24fps. It will then lock up in FCP as it will not assume that the audio needs to be pulled to compensate. I have a full thread on this here

[minister]

hi,

sounds confusing.

a few things, though. AIFF does not contain frame rate data. There is no "chunk" for that. There is a chunk for markers for loops and such. furthermore, the SPEED of the audio file is governed by the SR clock. So, putting an audio file with "drop frame code" into a 24fps timeline will not screw things up as you suggest. as long as the running time is the same, you can put an audio file creating against one frame rate into the seuquence of a completely other rate and it will still play in sync.

when you say "30" do you mean 29.97? or do mean 30? i know there is 30 drop, just trying to clarify....

here is what i suspect : with this one sequence, are you SURE that it was ALWAYS 24 fps? upon capture? FCP has an annoying habit (feature) of giving you drop frame as a default. was the sequence set up properly in the beginning? when you highlight the sequence in FCP and get settings (apple-0) and look at timeline options, what does it say?

who did the telecine transfer?

it also sounds like a simple matter of pull. somewhere in the transfer, you are .1% off -- 20 frames in 14 mintues would be about 20 frames.........

[minister]

Howard and i must have been posting at the same time.

I think he is on to it with the origin of the FCP capture settings...

[Sonsey]

Hi Tom,

Oh yeah... I've actually checked this and it is 100% repeatable... I think it's an offshoot of the Cinema Tools function, which allows you to return a 29.97 telecine'd file to a true 24 file. FCP assumes (as it's very good at) that ANY audio coming in when the capture setting is set to 29.97 and the sequence is 24 MUST be pulled down and therefore "helpfully" (and I use that word loosely) pulls it back up for you. Kinda makes sense if you were recapturing audio from the original video sources, but you would think that an imported file would simply playback as is... I guess that's "thinking different"

[Sonsey]

Oh yeah... I should add Apple is aware of this and it is expected behaviour for FCP...

[minister]

Hi Howard!

At least it is a "pref" in AVID.

[Sonsey]

Hey Tom...

As it should be in FCP! One of many things that give me an intense love/hate relationship with the program...

So this doesn't get too far off topic... Smack... did you work it out?

[smack5099]

Thanks for your help Howard and Tom. I guess I'll just stick with this Quicktime workaround for now (for making DVD copies) and then when it goes to final format I'll probably just string together the original AIFF files to be laid off directly to the format. (Yeah, I'm anal.)

I guess what I still don't understand is A) why did it just happen with this one sequence, and B) why did it work fine with this sequence until now? If, as you say, I had the capture settings set to 29.97 when starting this sequence, why didn't the problem manifest at the beginning? (And - though I can't be positive - I'm pretty sure I created all these sequences at the same time.) Oh well. The joys of Final Cut, I guess.

I should point out that the original sound files were never "captured" per se, as they were recorded directly to hard drive at 24fps/48k.

Thanks again for the info. My brain is sore.

[smack5099]

I guess there's one more thing that confuses me, Howard. You said it has to do with the default capture settings when the sequence is created. Do you mean the sequence from which the OMF file is exported to Pro Tools, or the sequence that the finished AIFF mix is dropped into? I realize that 99% of the time these sequences are one and the same, but the reason I ask is that, like I said, when I import the AIFF file into FCP, it treats it as a 30fps drop-frame clip in the browser/viewer *before* I've dropped it into the sequence, even though the AIFF files from all the other sequences are treated as 24fps.

At this point, it's not really critical, but I'm still struggling to wrap my brain around this...